fernandez jo t 2011
DESCRIPTION
Phasor measurement unit (PMU) applications on power grid monitoring systemshave been implemented since the early ninety’s. Large monitoring system networkperformance relies on the consistent measurements of PMUs across the system. This hasbecome a major challenge for designers since large networks use PMUs from variousmanufacturers who likely implement different synchrophasor technologies to perform thephasor estimations. The current synchrophasor standard, the IEEE C37.118-2005Synchrophasor Standard, covers adequately the steady-state characterization of PMUs butdoes not specify transient condition requirements. The North American SynchrophasorInitiative (NASPI) has developed a guide outlining the several tests required for dynamiccharacterization of PMUs. The National Institute of Standards and Technology (NIST)developed two PMU testing stands for steady-state conformance with the currentstandard and for dynamic performance testing. Since May 2010, Virginia Tech has beenworking closely with the NIST in developing a PMU testing system similar to the NISTdesigns for commercial testing of PMUs and research purposes, the Virginia TechCalibration System. This thesis focuses on assessing the system accuracy differencesbetween the designs, and the software interface modifications to adapt the new hardware.TRANSCRIPT
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 161
The Virginia Tech Calibration System
Javier O Fernandez
Thesis submitted to the faculty of theVirginia Polytechnic Institute and State University
in partial fulfillment of the requirements for the degree of
Master of Science
InElectrical Engineering
Virgilio A Centeno ChairJaime De La Ree Lopez
Richard W Conners
Keywords calibration system pmu calibration pmu phasor
May 3 2011Blacksburg VA
Copyright 2011 Javier O Fernandez
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 261
The Virginia Tech Calibration System
Javier O Fernandez
ABSTRACT
Phasor measurement unit (PMU) applications on power grid monitoring systems
have been implemented since the early ninetyrsquos Large monitoring system network
performance relies on the consistent measurements of PMUs across the system This has
become a major challenge for designers since large networks use PMUs from various
manufacturers who likely implement different synchrophasor technologies to perform the
phasor estimations The current synchrophasor standard the IEEE C37118-2005
Synchrophasor Standard covers adequately the steady-state characterization of PMUs but
does not specify transient condition requirements The North American Synchrophasor
Initiative (NASPI) has developed a guide outlining the several tests required for dynamic
characterization of PMUs The National Institute of Standards and Technology (NIST)
developed two PMU testing stands for steady-state conformance with the current
standard and for dynamic performance testing Since May 2010 Virginia Tech has been
working closely with the NIST in developing a PMU testing system similar to the NISTdesigns for commercial testing of PMUs and research purposes the Virginia Tech
Calibration System This thesis focuses on assessing the system accuracy differences
between the designs and the software interface modifications to adapt the new hardware
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 361
iii
List of Figures v
List of Tables vi
List of Acronyms vii
1 Introduction 1
2 Literature Review 4
21 The IEEE 1344-1995 Synchrophasor Standard 4
22 The IEEE C37118-2005 Synchrophasor Standard 5
23 Need for a New Synchrophasor Standard 7
3 The Virginia Tech Calibration System Design 9
31 Requirements Decomposition 9
311 System Performance 9
3111 Time Source 11
3112 Data Acquisition 12 3113 Signal Processing 12
312 Parameter Testing 13
3121 Steady-State Testing 13
3122 Dynamic Testing 15
3123 Protocol Testing 15
313 Documentation 15
32 System Definition 15
321 System Description and High-level Architectural Depiction 16
33 Steady-state Design 17 331 Time Source 18
332 Signal Generation 18
333 Data Acquisition 19
334 Signal Processing 19
335 Clock Synchronization 20
336 Signal Attenuation 21
337 DUT interface 21
34 Dynamic Testing Design 22
341 Signal Generation 22
35 Calibration 23
4 Steady-state Testing 24
41 Accuracy and Time Alignment 24
411 Magnitude Accuracy 24
412 Phase Accuracy 27
413 Frequency Accuracy 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 461
iv
5 Dynamic Testing 35
51 Step Change response 35
511 Dynamic Magnitude Response 37
512 Dynamic Phase Response 39
513 Dynamic Frequency Response 43
6 Conclusions and Recommendations 48
References 49
Appendix A NI PXI-6682 Timing Module Technical Specifications 51
Appendix B Omicron CMC 156 EP Technical Specifications 52
Appendix C NI PXIe-6356 Data Acquisition Module Technical Specifications 53
Appendix D NI PXI-6733 Analog Output Module Technical Specifications 54
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 561
v
List of Figures
Figure 11 NIST phase measurement unit calibration system 3
Figure 12 Diagram of NIST dynamic test system 3 Figure 21 Convention for phasor representation 4
Figure 22 Convention for synchrophasor representation 5
Figure 23 Phasor measurement process with TVE error detection criteria 6
Figure 31 The Virginia Tech Calibration System requirements decomposition 9
Figure 32 The Virginia Tech Calibration System high level architectural depiction 16
Figure 33 Phase calibration of reference PMU with the 1PPS clock signal 23
Figure 41 MagTestRunNI VI front panel 25
Figure 42 MagTestRunNI VI block diagram 26
Figure 43 Voltage magnitude accuracy test results 27
Figure 44 PhaseTestRunNI VI front panel 28
Figure 45 PhaseTestRunNI VI block diagram 29 Figure 46 Phase accuracy test results 30
Figure 47 FreqTestRunNI VI front panel 32
Figure 48 FreqTestRunNI VI block diagram 33
Figure 49 Frequency accuracy test results 34
Figure 51 NI_DUT_Step_add VI block diagram 36
Figure 52 Run_Step_Test_on_DUTs_add VI front panel 37
Figure 53 Magnitude step change test signal 38
Figure 54 Magnitude step change test results 39
Figure 55 Phase step change test signal (-45˚) 40
Figure 56 Phases step change test signal (+45˚) 41
Figure 57 Phase step change test results (-45˚) 42
Figure 58 Phase step change test results (+45˚) 43
Figure 59 Frequency step change test signal (-2Hz) 44
Figure 510 Frequency step change test signal (+2Hz) 45
Figure 511 Frequency step change test results (-2Hz) 46
Figure 512 Frequency step change test results (+2Hz) 47
Figure B1 Omicron CMC 156 technical specifications 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 661
vi
List of Tables
Table 21 Required PMU reporting rates 6
Table 31 Hardware modules used in the NIST designs 11 Table 32 Influence quantities and allowable error limits for compliance levels 0-1 14
Table 33 Major processing component descriptions in the Virginia Tech Calibration System 16
Table 34 Hardware used in the Virginia Tech Calibration System steady-state design 17
Table 35 Software interface VIs in the Virginia Tech Calibration System 17
Table 36 Time source module accuracy comparison with the NIST designs 18
Table 37 Signal generation module accuracy comparison with the NIST designs 19
Table 38 Data acquisition module accuracy comparison with the NIST designs 19
Table 39 Signal processing module accuracy comparison with the NIST designs 20
Table 310 Synchronization source accuracy comparison with the NIST designs 21
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design 22
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design 22
Table A1 NI PXI-6682H synchronization accuracy 51
Table C1 NI PXIe-6356 technical specifications 53
Table D1 NI PXI-6733 technical specifications 54
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 761
vii
List of Acronyms
PMU Phasor measurement unit
NASPI North American Synchrophasor InitiativeNIST National institute of standards and technology
WAMPAC Wide-area monitoring protection and control
DOE Department of Energy
PSTT Performance and Standards Task Team
WECC Western Electricity Coordinating Council
CERTS Consortium for Electric Reliability Technology Solutions
EIPP Eastern Interconnection Phasor Project
SOC Second of Century
TVE Total vector error
GPS Global Positioning System
NI National Instruments
DUT Device under testVI Virtual Instrument
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 861
P a g e | 1
The Virginia Tech Calibration System copy 2011 Javier Fernandez
1 INTRODUCTION
The Phasor Measurement Unit (PMU) also known as synchrophasor takes time
synchronized measurements of voltage and current signals on a power grid This device was first
developed by researchers at Virginia Tech in Blacksburg VA in the late 1980rsquos PMU devicesare commercialized as a stand-alone unit or the PMU function can be integrated into a protective
relay or other device
PMU applications on wide-area monitoring protection and control (WAMPAC) systems
have gained worldwide acceptance since its emergence as commercial devices in the power
industry market in early 1990rsquos Brazil and China are currently deploying large WAMPAC
systems to control their power grids [2 3] The US Department Of Energy (DOE) as a response
to the 1996 and 2003 blackouts has sponsored improvements in the control of power grids that
involve the use of PMU-based WAMPAC systems
WAMPAC systems integrate information from selected local networks to a remote
location to minimize the widespread effects of large disturbances Most large PMU
implementations on wide-area monitoring networks use devices from various manufacturers
which present a challenge to ensure consistent phasor readings as they likely use different
measurement technologies For such systems WAMPAC system performance relies on the PMU
conformance to the same synchrophasor standard
In December 2005 the IEEE C37118-2005 Synchrophasor Standard [1] to replace the
IEEE 1344-1995(R2001) Synchrophasor Standard [4] developed in March 2001 These
standards define the synchrophasor phasor measurements in power grids for interoperability and
interfacing with associated equipment The IEEE Standard for Synchrophasors for Power
Systems C37118-2005 [1] covers adequately the PMU characterization under steady-state
conditions but falls short under transient conditions Consistent dynamic performance among
PMUs is of great importance for most current phasor applications
In 2007 the North America efforts in phasor technology were combined and the North
American Synchro Phasor Initiative (NASPI) emerged with the intent to coordinate phasor
activities in the entire North American grid The increased role for industry collaborations of the
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 961
P a g e | 2
The Virginia Tech Calibration System copy 2011 Javier Fernandez
NASPI working group and task teams has already extended to a more global collaboration of
industry best practices while the DOE continues to support phasor research Today there are
seven task teams focusing on various aspects of phasor activities[5]
Amongst the task teams is the Performance and Standards Task Team (PSTT) The PSTTis chartered to coordinate and act as liaison to standardization efforts and to determine consistent
and satisfactory performance of synchronized measurement devices and systems by creating
guidelines and reports in accordance with best practices Many of the PSTT members are active
in many international industry activities which help the Task Team members to coordinate the
development of phasor-related standards both within the NASPI as well as outside of North
America[5]
The PSTT team developed two complementary documents to the IEEE C37118 PMU
Testing Guide [6] and SynchroPhasor Accuracy Characterization [7]
This Guide describes performance and interoperability tests and calibration procedures
for PMUs used in the electric power industry to monitor the condition of the electric power grid
Conformance tests with the IEEE C37118-2005 Synchrophasor Standard and extended test
procedures to address the dynamic performance requirements not specified in the IEEE C37118-
2005 Synchrophasor Standard are included [1] This considers performance standards established
by the Western Electricity Coordinating Council (WECC) [8] Laboratory PMU test and
calibration procedures described[6]
To promote better test and measurement procedures for PMU test and calibration the
National Institute of Standards and Technology (NIST) in US has established a
SynchroMetrology Laboratory in support of the Consortium for Electric Reliability Technology
Solutions (CERTS) which sponsors the NASPI (was EIPP) The laboratory is established to
develop test and calibration methods to combine traditional waveform parameter metrology with
procedures to reference these values to a synchronized timing source such as UTC[3]
The NIST SynchroMetrology Laboratory developed two calibration systems as shown in
Figures 11 and 12 one for testing PMU for compliance with the IEEE C37118-2005
Synchrophasor Standard [1] and the other for dynamic characterization on PMUs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1061
P a g e | 3
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 11 NIST Phase Measurement Unit Calibration System [Stenbakken 2007] Illustrated
under ldquoFair Userdquo copyright guidelines
The purpose of developing the NIST Dynamic Test System includes the characterizationof commercial PMUs under dynamic power system conditions and the use of this data for the
development of new dynamic performance requirements for PMUs
Figure 12 Diagram of NIST Dynamic Test System [Stenbakken 2007] Illustrated under ldquoFair
Userdquo copyright guidelines
In this thesis project the NIST designs for steady-state calibration testing and dynamic
characterization of PMUs were implemented with new equipment the Virginia Tech Calibration
System This thesis provides an overview of the NIST designs and explains the required
modifications to integrate the new hardware
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1161
P a g e | 4
The Virginia Tech Calibration System copy 2011 Javier Fernandez
2 LITERATURE REVIEW
21 The IEEE 1344-1995 Synchrophasor Standard
This was the first PMU standard approved in December 1995 and reaffirmed in March
2005 It addresses synchronization of data sampling data-to-phasor conversions and formats for
timing input and phasor data output from a PMU [10]
The standard defined a precise method for time stamping data samples and phasor
measurements as shown in Figure 21 listed the requirements for the time synchronizing sources
and specified the allowed types of time input IRIG-B format 1 PPS and the high precision time
format
Figure 21 Convention for phasor representation [IEEE Standard for Synchrophasors for PowerSystems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
It approved the use of either synchronized or non-synchronized sampling requiring
phase-locked sampling for synchronized sampling systems or equivalent phasor measurements
for non-synchronizing sampling systems The standard also defined a resynchronization method
for external time and sampling sources
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1261
P a g e | 5
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For steady state analysis it required that the phasor measurements followed the off-
nominal frequencies It also defined a convention for phasor representation independent from
window size The standard also requires phase compensations for delays internal to the PMU
It also defined the message format required for data reporting from the PMU organizedas data header and configuration frames and for commands received by the PMU
22 The IEEE C37118-2005 Synchrophasor Standard
This is the current PMU standard approved in December 2005 It addresses the definition
of a synchronized phasor time synchronization application of timetags method to verify
measurement compliance with the standard and message formats for communication with a
PMU [11]
This standard improved the time stamping method defined in the IEEE 1344-1995
Synchrophasor Standard [4] by redefining the phasor timetag as a group of three numbers a
second-of-century (SOC) count a fraction-of-second count and a time status value It also
allowed data format compatibility with other standards such as the IEC 61850 Standard
It defined the convention for phasor representation as an absolute phasor with a phase
locked to nominal frequency and synchronized to UTC time as shown in Figure 22
Figure 22 Convention for synchrophasor representation [IEEE Standard for Synchrophasors forPower Systems 2001] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1361
P a g e | 6
The Virginia Tech Calibration System copy 2011 Javier Fernandez
This standard specified the required phasor reporting rates for 50 Hz and 60 Hz as shown
in Table 21 the actual used rate being selected by the user
Table 21 Required PMU reporting rates [IEEE Standard for Synchrophasors for Power Systems2006] Illustrated under ldquoFair Userdquo copyright guidelines
It defined the steady-state condition where the magnitude frequency and phase of the
test signal remained constant during the time of measurement
This standard introduced the concept of total vector error (TVE) for quantifying phasor
measurement errors as defined in Figure 23
Figure 23 Phasor measurement process with TVE error detection criteria [IEEE Standard forSynchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1461
P a g e | 7
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The TVE is a comparison between a theoretical phasor X and an input phasor
measured by the PMU If a phase shift of ( is added to both X and the phasors would
rotate keeping the ratio between the magnitudes and the TVE constant
This standard also defined the error limits using the TVE concept for the recommended
steady-state compliance tests on the influence quantities shown in Table 32
The NIST developed the NIST PMU Calibration System for testing PMUs for
compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This steady-state
calibration test stand design is described in [9 11]
23 Need for a New Synchrophasor Standard
Some of the IEEE 1344-1995 Synchrophasor Standard [4] limitations were addressed in
the current standard The first standard defined the phasor requirements only at the zero
crossings or 1PPS second mark It did not specify any requirements for dynamic responses such
as measurement response time or accuracy under transient conditions The data format and the
serial type of interface required were not compatible with industry network communication
standards
The IEEE C37118-2005 Synchrophasor Standard [1] covers adequately most the steady-
state PMU characterization however there are limitations that will need to be addressed in the
new standard It does not specify frequency accuracy requirements Also lack of testing
procedures requirements in the current standard and unavailability of testing equipment are
major issues for PMU testing and calibration [5]
If the input frequency becomes off-nominal the mismatch induces a rotation between the
estimated phasor and the measured phasor causing the TVE to change inside the time window
Possible solutions are suggested in [12 13] including a modification to the standard to add a
TVE limit for the time window or a maximum frequency deviation for the compliance tests
Most importantly to support the increasing demand for high quality PMU applications on
large WAMS the current PMU standard needs to be further developed Future standards should
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1561
P a g e | 8
The Virginia Tech Calibration System copy 2011 Javier Fernandez
show a higher level of detail for dynamic PMU performance requirements testing procedures
and documentation that could guarantee homogeneous performance conformance among PMU
from different manufacturers
The NIST developed the NIST Dynamic Test System for testing PMU performance undertransient conditions and the use of this data for the development of new dynamic performance
requirements for PMUs This PMU dynamic characterization test stand design is described in [10
14 15]
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 261
The Virginia Tech Calibration System
Javier O Fernandez
ABSTRACT
Phasor measurement unit (PMU) applications on power grid monitoring systems
have been implemented since the early ninetyrsquos Large monitoring system network
performance relies on the consistent measurements of PMUs across the system This has
become a major challenge for designers since large networks use PMUs from various
manufacturers who likely implement different synchrophasor technologies to perform the
phasor estimations The current synchrophasor standard the IEEE C37118-2005
Synchrophasor Standard covers adequately the steady-state characterization of PMUs but
does not specify transient condition requirements The North American Synchrophasor
Initiative (NASPI) has developed a guide outlining the several tests required for dynamic
characterization of PMUs The National Institute of Standards and Technology (NIST)
developed two PMU testing stands for steady-state conformance with the current
standard and for dynamic performance testing Since May 2010 Virginia Tech has been
working closely with the NIST in developing a PMU testing system similar to the NISTdesigns for commercial testing of PMUs and research purposes the Virginia Tech
Calibration System This thesis focuses on assessing the system accuracy differences
between the designs and the software interface modifications to adapt the new hardware
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 361
iii
List of Figures v
List of Tables vi
List of Acronyms vii
1 Introduction 1
2 Literature Review 4
21 The IEEE 1344-1995 Synchrophasor Standard 4
22 The IEEE C37118-2005 Synchrophasor Standard 5
23 Need for a New Synchrophasor Standard 7
3 The Virginia Tech Calibration System Design 9
31 Requirements Decomposition 9
311 System Performance 9
3111 Time Source 11
3112 Data Acquisition 12 3113 Signal Processing 12
312 Parameter Testing 13
3121 Steady-State Testing 13
3122 Dynamic Testing 15
3123 Protocol Testing 15
313 Documentation 15
32 System Definition 15
321 System Description and High-level Architectural Depiction 16
33 Steady-state Design 17 331 Time Source 18
332 Signal Generation 18
333 Data Acquisition 19
334 Signal Processing 19
335 Clock Synchronization 20
336 Signal Attenuation 21
337 DUT interface 21
34 Dynamic Testing Design 22
341 Signal Generation 22
35 Calibration 23
4 Steady-state Testing 24
41 Accuracy and Time Alignment 24
411 Magnitude Accuracy 24
412 Phase Accuracy 27
413 Frequency Accuracy 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 461
iv
5 Dynamic Testing 35
51 Step Change response 35
511 Dynamic Magnitude Response 37
512 Dynamic Phase Response 39
513 Dynamic Frequency Response 43
6 Conclusions and Recommendations 48
References 49
Appendix A NI PXI-6682 Timing Module Technical Specifications 51
Appendix B Omicron CMC 156 EP Technical Specifications 52
Appendix C NI PXIe-6356 Data Acquisition Module Technical Specifications 53
Appendix D NI PXI-6733 Analog Output Module Technical Specifications 54
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 561
v
List of Figures
Figure 11 NIST phase measurement unit calibration system 3
Figure 12 Diagram of NIST dynamic test system 3 Figure 21 Convention for phasor representation 4
Figure 22 Convention for synchrophasor representation 5
Figure 23 Phasor measurement process with TVE error detection criteria 6
Figure 31 The Virginia Tech Calibration System requirements decomposition 9
Figure 32 The Virginia Tech Calibration System high level architectural depiction 16
Figure 33 Phase calibration of reference PMU with the 1PPS clock signal 23
Figure 41 MagTestRunNI VI front panel 25
Figure 42 MagTestRunNI VI block diagram 26
Figure 43 Voltage magnitude accuracy test results 27
Figure 44 PhaseTestRunNI VI front panel 28
Figure 45 PhaseTestRunNI VI block diagram 29 Figure 46 Phase accuracy test results 30
Figure 47 FreqTestRunNI VI front panel 32
Figure 48 FreqTestRunNI VI block diagram 33
Figure 49 Frequency accuracy test results 34
Figure 51 NI_DUT_Step_add VI block diagram 36
Figure 52 Run_Step_Test_on_DUTs_add VI front panel 37
Figure 53 Magnitude step change test signal 38
Figure 54 Magnitude step change test results 39
Figure 55 Phase step change test signal (-45˚) 40
Figure 56 Phases step change test signal (+45˚) 41
Figure 57 Phase step change test results (-45˚) 42
Figure 58 Phase step change test results (+45˚) 43
Figure 59 Frequency step change test signal (-2Hz) 44
Figure 510 Frequency step change test signal (+2Hz) 45
Figure 511 Frequency step change test results (-2Hz) 46
Figure 512 Frequency step change test results (+2Hz) 47
Figure B1 Omicron CMC 156 technical specifications 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 661
vi
List of Tables
Table 21 Required PMU reporting rates 6
Table 31 Hardware modules used in the NIST designs 11 Table 32 Influence quantities and allowable error limits for compliance levels 0-1 14
Table 33 Major processing component descriptions in the Virginia Tech Calibration System 16
Table 34 Hardware used in the Virginia Tech Calibration System steady-state design 17
Table 35 Software interface VIs in the Virginia Tech Calibration System 17
Table 36 Time source module accuracy comparison with the NIST designs 18
Table 37 Signal generation module accuracy comparison with the NIST designs 19
Table 38 Data acquisition module accuracy comparison with the NIST designs 19
Table 39 Signal processing module accuracy comparison with the NIST designs 20
Table 310 Synchronization source accuracy comparison with the NIST designs 21
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design 22
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design 22
Table A1 NI PXI-6682H synchronization accuracy 51
Table C1 NI PXIe-6356 technical specifications 53
Table D1 NI PXI-6733 technical specifications 54
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 761
vii
List of Acronyms
PMU Phasor measurement unit
NASPI North American Synchrophasor InitiativeNIST National institute of standards and technology
WAMPAC Wide-area monitoring protection and control
DOE Department of Energy
PSTT Performance and Standards Task Team
WECC Western Electricity Coordinating Council
CERTS Consortium for Electric Reliability Technology Solutions
EIPP Eastern Interconnection Phasor Project
SOC Second of Century
TVE Total vector error
GPS Global Positioning System
NI National Instruments
DUT Device under testVI Virtual Instrument
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 861
P a g e | 1
The Virginia Tech Calibration System copy 2011 Javier Fernandez
1 INTRODUCTION
The Phasor Measurement Unit (PMU) also known as synchrophasor takes time
synchronized measurements of voltage and current signals on a power grid This device was first
developed by researchers at Virginia Tech in Blacksburg VA in the late 1980rsquos PMU devicesare commercialized as a stand-alone unit or the PMU function can be integrated into a protective
relay or other device
PMU applications on wide-area monitoring protection and control (WAMPAC) systems
have gained worldwide acceptance since its emergence as commercial devices in the power
industry market in early 1990rsquos Brazil and China are currently deploying large WAMPAC
systems to control their power grids [2 3] The US Department Of Energy (DOE) as a response
to the 1996 and 2003 blackouts has sponsored improvements in the control of power grids that
involve the use of PMU-based WAMPAC systems
WAMPAC systems integrate information from selected local networks to a remote
location to minimize the widespread effects of large disturbances Most large PMU
implementations on wide-area monitoring networks use devices from various manufacturers
which present a challenge to ensure consistent phasor readings as they likely use different
measurement technologies For such systems WAMPAC system performance relies on the PMU
conformance to the same synchrophasor standard
In December 2005 the IEEE C37118-2005 Synchrophasor Standard [1] to replace the
IEEE 1344-1995(R2001) Synchrophasor Standard [4] developed in March 2001 These
standards define the synchrophasor phasor measurements in power grids for interoperability and
interfacing with associated equipment The IEEE Standard for Synchrophasors for Power
Systems C37118-2005 [1] covers adequately the PMU characterization under steady-state
conditions but falls short under transient conditions Consistent dynamic performance among
PMUs is of great importance for most current phasor applications
In 2007 the North America efforts in phasor technology were combined and the North
American Synchro Phasor Initiative (NASPI) emerged with the intent to coordinate phasor
activities in the entire North American grid The increased role for industry collaborations of the
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 961
P a g e | 2
The Virginia Tech Calibration System copy 2011 Javier Fernandez
NASPI working group and task teams has already extended to a more global collaboration of
industry best practices while the DOE continues to support phasor research Today there are
seven task teams focusing on various aspects of phasor activities[5]
Amongst the task teams is the Performance and Standards Task Team (PSTT) The PSTTis chartered to coordinate and act as liaison to standardization efforts and to determine consistent
and satisfactory performance of synchronized measurement devices and systems by creating
guidelines and reports in accordance with best practices Many of the PSTT members are active
in many international industry activities which help the Task Team members to coordinate the
development of phasor-related standards both within the NASPI as well as outside of North
America[5]
The PSTT team developed two complementary documents to the IEEE C37118 PMU
Testing Guide [6] and SynchroPhasor Accuracy Characterization [7]
This Guide describes performance and interoperability tests and calibration procedures
for PMUs used in the electric power industry to monitor the condition of the electric power grid
Conformance tests with the IEEE C37118-2005 Synchrophasor Standard and extended test
procedures to address the dynamic performance requirements not specified in the IEEE C37118-
2005 Synchrophasor Standard are included [1] This considers performance standards established
by the Western Electricity Coordinating Council (WECC) [8] Laboratory PMU test and
calibration procedures described[6]
To promote better test and measurement procedures for PMU test and calibration the
National Institute of Standards and Technology (NIST) in US has established a
SynchroMetrology Laboratory in support of the Consortium for Electric Reliability Technology
Solutions (CERTS) which sponsors the NASPI (was EIPP) The laboratory is established to
develop test and calibration methods to combine traditional waveform parameter metrology with
procedures to reference these values to a synchronized timing source such as UTC[3]
The NIST SynchroMetrology Laboratory developed two calibration systems as shown in
Figures 11 and 12 one for testing PMU for compliance with the IEEE C37118-2005
Synchrophasor Standard [1] and the other for dynamic characterization on PMUs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1061
P a g e | 3
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 11 NIST Phase Measurement Unit Calibration System [Stenbakken 2007] Illustrated
under ldquoFair Userdquo copyright guidelines
The purpose of developing the NIST Dynamic Test System includes the characterizationof commercial PMUs under dynamic power system conditions and the use of this data for the
development of new dynamic performance requirements for PMUs
Figure 12 Diagram of NIST Dynamic Test System [Stenbakken 2007] Illustrated under ldquoFair
Userdquo copyright guidelines
In this thesis project the NIST designs for steady-state calibration testing and dynamic
characterization of PMUs were implemented with new equipment the Virginia Tech Calibration
System This thesis provides an overview of the NIST designs and explains the required
modifications to integrate the new hardware
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1161
P a g e | 4
The Virginia Tech Calibration System copy 2011 Javier Fernandez
2 LITERATURE REVIEW
21 The IEEE 1344-1995 Synchrophasor Standard
This was the first PMU standard approved in December 1995 and reaffirmed in March
2005 It addresses synchronization of data sampling data-to-phasor conversions and formats for
timing input and phasor data output from a PMU [10]
The standard defined a precise method for time stamping data samples and phasor
measurements as shown in Figure 21 listed the requirements for the time synchronizing sources
and specified the allowed types of time input IRIG-B format 1 PPS and the high precision time
format
Figure 21 Convention for phasor representation [IEEE Standard for Synchrophasors for PowerSystems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
It approved the use of either synchronized or non-synchronized sampling requiring
phase-locked sampling for synchronized sampling systems or equivalent phasor measurements
for non-synchronizing sampling systems The standard also defined a resynchronization method
for external time and sampling sources
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1261
P a g e | 5
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For steady state analysis it required that the phasor measurements followed the off-
nominal frequencies It also defined a convention for phasor representation independent from
window size The standard also requires phase compensations for delays internal to the PMU
It also defined the message format required for data reporting from the PMU organizedas data header and configuration frames and for commands received by the PMU
22 The IEEE C37118-2005 Synchrophasor Standard
This is the current PMU standard approved in December 2005 It addresses the definition
of a synchronized phasor time synchronization application of timetags method to verify
measurement compliance with the standard and message formats for communication with a
PMU [11]
This standard improved the time stamping method defined in the IEEE 1344-1995
Synchrophasor Standard [4] by redefining the phasor timetag as a group of three numbers a
second-of-century (SOC) count a fraction-of-second count and a time status value It also
allowed data format compatibility with other standards such as the IEC 61850 Standard
It defined the convention for phasor representation as an absolute phasor with a phase
locked to nominal frequency and synchronized to UTC time as shown in Figure 22
Figure 22 Convention for synchrophasor representation [IEEE Standard for Synchrophasors forPower Systems 2001] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1361
P a g e | 6
The Virginia Tech Calibration System copy 2011 Javier Fernandez
This standard specified the required phasor reporting rates for 50 Hz and 60 Hz as shown
in Table 21 the actual used rate being selected by the user
Table 21 Required PMU reporting rates [IEEE Standard for Synchrophasors for Power Systems2006] Illustrated under ldquoFair Userdquo copyright guidelines
It defined the steady-state condition where the magnitude frequency and phase of the
test signal remained constant during the time of measurement
This standard introduced the concept of total vector error (TVE) for quantifying phasor
measurement errors as defined in Figure 23
Figure 23 Phasor measurement process with TVE error detection criteria [IEEE Standard forSynchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1461
P a g e | 7
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The TVE is a comparison between a theoretical phasor X and an input phasor
measured by the PMU If a phase shift of ( is added to both X and the phasors would
rotate keeping the ratio between the magnitudes and the TVE constant
This standard also defined the error limits using the TVE concept for the recommended
steady-state compliance tests on the influence quantities shown in Table 32
The NIST developed the NIST PMU Calibration System for testing PMUs for
compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This steady-state
calibration test stand design is described in [9 11]
23 Need for a New Synchrophasor Standard
Some of the IEEE 1344-1995 Synchrophasor Standard [4] limitations were addressed in
the current standard The first standard defined the phasor requirements only at the zero
crossings or 1PPS second mark It did not specify any requirements for dynamic responses such
as measurement response time or accuracy under transient conditions The data format and the
serial type of interface required were not compatible with industry network communication
standards
The IEEE C37118-2005 Synchrophasor Standard [1] covers adequately most the steady-
state PMU characterization however there are limitations that will need to be addressed in the
new standard It does not specify frequency accuracy requirements Also lack of testing
procedures requirements in the current standard and unavailability of testing equipment are
major issues for PMU testing and calibration [5]
If the input frequency becomes off-nominal the mismatch induces a rotation between the
estimated phasor and the measured phasor causing the TVE to change inside the time window
Possible solutions are suggested in [12 13] including a modification to the standard to add a
TVE limit for the time window or a maximum frequency deviation for the compliance tests
Most importantly to support the increasing demand for high quality PMU applications on
large WAMS the current PMU standard needs to be further developed Future standards should
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1561
P a g e | 8
The Virginia Tech Calibration System copy 2011 Javier Fernandez
show a higher level of detail for dynamic PMU performance requirements testing procedures
and documentation that could guarantee homogeneous performance conformance among PMU
from different manufacturers
The NIST developed the NIST Dynamic Test System for testing PMU performance undertransient conditions and the use of this data for the development of new dynamic performance
requirements for PMUs This PMU dynamic characterization test stand design is described in [10
14 15]
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 361
iii
List of Figures v
List of Tables vi
List of Acronyms vii
1 Introduction 1
2 Literature Review 4
21 The IEEE 1344-1995 Synchrophasor Standard 4
22 The IEEE C37118-2005 Synchrophasor Standard 5
23 Need for a New Synchrophasor Standard 7
3 The Virginia Tech Calibration System Design 9
31 Requirements Decomposition 9
311 System Performance 9
3111 Time Source 11
3112 Data Acquisition 12 3113 Signal Processing 12
312 Parameter Testing 13
3121 Steady-State Testing 13
3122 Dynamic Testing 15
3123 Protocol Testing 15
313 Documentation 15
32 System Definition 15
321 System Description and High-level Architectural Depiction 16
33 Steady-state Design 17 331 Time Source 18
332 Signal Generation 18
333 Data Acquisition 19
334 Signal Processing 19
335 Clock Synchronization 20
336 Signal Attenuation 21
337 DUT interface 21
34 Dynamic Testing Design 22
341 Signal Generation 22
35 Calibration 23
4 Steady-state Testing 24
41 Accuracy and Time Alignment 24
411 Magnitude Accuracy 24
412 Phase Accuracy 27
413 Frequency Accuracy 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 461
iv
5 Dynamic Testing 35
51 Step Change response 35
511 Dynamic Magnitude Response 37
512 Dynamic Phase Response 39
513 Dynamic Frequency Response 43
6 Conclusions and Recommendations 48
References 49
Appendix A NI PXI-6682 Timing Module Technical Specifications 51
Appendix B Omicron CMC 156 EP Technical Specifications 52
Appendix C NI PXIe-6356 Data Acquisition Module Technical Specifications 53
Appendix D NI PXI-6733 Analog Output Module Technical Specifications 54
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 561
v
List of Figures
Figure 11 NIST phase measurement unit calibration system 3
Figure 12 Diagram of NIST dynamic test system 3 Figure 21 Convention for phasor representation 4
Figure 22 Convention for synchrophasor representation 5
Figure 23 Phasor measurement process with TVE error detection criteria 6
Figure 31 The Virginia Tech Calibration System requirements decomposition 9
Figure 32 The Virginia Tech Calibration System high level architectural depiction 16
Figure 33 Phase calibration of reference PMU with the 1PPS clock signal 23
Figure 41 MagTestRunNI VI front panel 25
Figure 42 MagTestRunNI VI block diagram 26
Figure 43 Voltage magnitude accuracy test results 27
Figure 44 PhaseTestRunNI VI front panel 28
Figure 45 PhaseTestRunNI VI block diagram 29 Figure 46 Phase accuracy test results 30
Figure 47 FreqTestRunNI VI front panel 32
Figure 48 FreqTestRunNI VI block diagram 33
Figure 49 Frequency accuracy test results 34
Figure 51 NI_DUT_Step_add VI block diagram 36
Figure 52 Run_Step_Test_on_DUTs_add VI front panel 37
Figure 53 Magnitude step change test signal 38
Figure 54 Magnitude step change test results 39
Figure 55 Phase step change test signal (-45˚) 40
Figure 56 Phases step change test signal (+45˚) 41
Figure 57 Phase step change test results (-45˚) 42
Figure 58 Phase step change test results (+45˚) 43
Figure 59 Frequency step change test signal (-2Hz) 44
Figure 510 Frequency step change test signal (+2Hz) 45
Figure 511 Frequency step change test results (-2Hz) 46
Figure 512 Frequency step change test results (+2Hz) 47
Figure B1 Omicron CMC 156 technical specifications 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 661
vi
List of Tables
Table 21 Required PMU reporting rates 6
Table 31 Hardware modules used in the NIST designs 11 Table 32 Influence quantities and allowable error limits for compliance levels 0-1 14
Table 33 Major processing component descriptions in the Virginia Tech Calibration System 16
Table 34 Hardware used in the Virginia Tech Calibration System steady-state design 17
Table 35 Software interface VIs in the Virginia Tech Calibration System 17
Table 36 Time source module accuracy comparison with the NIST designs 18
Table 37 Signal generation module accuracy comparison with the NIST designs 19
Table 38 Data acquisition module accuracy comparison with the NIST designs 19
Table 39 Signal processing module accuracy comparison with the NIST designs 20
Table 310 Synchronization source accuracy comparison with the NIST designs 21
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design 22
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design 22
Table A1 NI PXI-6682H synchronization accuracy 51
Table C1 NI PXIe-6356 technical specifications 53
Table D1 NI PXI-6733 technical specifications 54
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 761
vii
List of Acronyms
PMU Phasor measurement unit
NASPI North American Synchrophasor InitiativeNIST National institute of standards and technology
WAMPAC Wide-area monitoring protection and control
DOE Department of Energy
PSTT Performance and Standards Task Team
WECC Western Electricity Coordinating Council
CERTS Consortium for Electric Reliability Technology Solutions
EIPP Eastern Interconnection Phasor Project
SOC Second of Century
TVE Total vector error
GPS Global Positioning System
NI National Instruments
DUT Device under testVI Virtual Instrument
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 861
P a g e | 1
The Virginia Tech Calibration System copy 2011 Javier Fernandez
1 INTRODUCTION
The Phasor Measurement Unit (PMU) also known as synchrophasor takes time
synchronized measurements of voltage and current signals on a power grid This device was first
developed by researchers at Virginia Tech in Blacksburg VA in the late 1980rsquos PMU devicesare commercialized as a stand-alone unit or the PMU function can be integrated into a protective
relay or other device
PMU applications on wide-area monitoring protection and control (WAMPAC) systems
have gained worldwide acceptance since its emergence as commercial devices in the power
industry market in early 1990rsquos Brazil and China are currently deploying large WAMPAC
systems to control their power grids [2 3] The US Department Of Energy (DOE) as a response
to the 1996 and 2003 blackouts has sponsored improvements in the control of power grids that
involve the use of PMU-based WAMPAC systems
WAMPAC systems integrate information from selected local networks to a remote
location to minimize the widespread effects of large disturbances Most large PMU
implementations on wide-area monitoring networks use devices from various manufacturers
which present a challenge to ensure consistent phasor readings as they likely use different
measurement technologies For such systems WAMPAC system performance relies on the PMU
conformance to the same synchrophasor standard
In December 2005 the IEEE C37118-2005 Synchrophasor Standard [1] to replace the
IEEE 1344-1995(R2001) Synchrophasor Standard [4] developed in March 2001 These
standards define the synchrophasor phasor measurements in power grids for interoperability and
interfacing with associated equipment The IEEE Standard for Synchrophasors for Power
Systems C37118-2005 [1] covers adequately the PMU characterization under steady-state
conditions but falls short under transient conditions Consistent dynamic performance among
PMUs is of great importance for most current phasor applications
In 2007 the North America efforts in phasor technology were combined and the North
American Synchro Phasor Initiative (NASPI) emerged with the intent to coordinate phasor
activities in the entire North American grid The increased role for industry collaborations of the
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 961
P a g e | 2
The Virginia Tech Calibration System copy 2011 Javier Fernandez
NASPI working group and task teams has already extended to a more global collaboration of
industry best practices while the DOE continues to support phasor research Today there are
seven task teams focusing on various aspects of phasor activities[5]
Amongst the task teams is the Performance and Standards Task Team (PSTT) The PSTTis chartered to coordinate and act as liaison to standardization efforts and to determine consistent
and satisfactory performance of synchronized measurement devices and systems by creating
guidelines and reports in accordance with best practices Many of the PSTT members are active
in many international industry activities which help the Task Team members to coordinate the
development of phasor-related standards both within the NASPI as well as outside of North
America[5]
The PSTT team developed two complementary documents to the IEEE C37118 PMU
Testing Guide [6] and SynchroPhasor Accuracy Characterization [7]
This Guide describes performance and interoperability tests and calibration procedures
for PMUs used in the electric power industry to monitor the condition of the electric power grid
Conformance tests with the IEEE C37118-2005 Synchrophasor Standard and extended test
procedures to address the dynamic performance requirements not specified in the IEEE C37118-
2005 Synchrophasor Standard are included [1] This considers performance standards established
by the Western Electricity Coordinating Council (WECC) [8] Laboratory PMU test and
calibration procedures described[6]
To promote better test and measurement procedures for PMU test and calibration the
National Institute of Standards and Technology (NIST) in US has established a
SynchroMetrology Laboratory in support of the Consortium for Electric Reliability Technology
Solutions (CERTS) which sponsors the NASPI (was EIPP) The laboratory is established to
develop test and calibration methods to combine traditional waveform parameter metrology with
procedures to reference these values to a synchronized timing source such as UTC[3]
The NIST SynchroMetrology Laboratory developed two calibration systems as shown in
Figures 11 and 12 one for testing PMU for compliance with the IEEE C37118-2005
Synchrophasor Standard [1] and the other for dynamic characterization on PMUs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1061
P a g e | 3
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 11 NIST Phase Measurement Unit Calibration System [Stenbakken 2007] Illustrated
under ldquoFair Userdquo copyright guidelines
The purpose of developing the NIST Dynamic Test System includes the characterizationof commercial PMUs under dynamic power system conditions and the use of this data for the
development of new dynamic performance requirements for PMUs
Figure 12 Diagram of NIST Dynamic Test System [Stenbakken 2007] Illustrated under ldquoFair
Userdquo copyright guidelines
In this thesis project the NIST designs for steady-state calibration testing and dynamic
characterization of PMUs were implemented with new equipment the Virginia Tech Calibration
System This thesis provides an overview of the NIST designs and explains the required
modifications to integrate the new hardware
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1161
P a g e | 4
The Virginia Tech Calibration System copy 2011 Javier Fernandez
2 LITERATURE REVIEW
21 The IEEE 1344-1995 Synchrophasor Standard
This was the first PMU standard approved in December 1995 and reaffirmed in March
2005 It addresses synchronization of data sampling data-to-phasor conversions and formats for
timing input and phasor data output from a PMU [10]
The standard defined a precise method for time stamping data samples and phasor
measurements as shown in Figure 21 listed the requirements for the time synchronizing sources
and specified the allowed types of time input IRIG-B format 1 PPS and the high precision time
format
Figure 21 Convention for phasor representation [IEEE Standard for Synchrophasors for PowerSystems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
It approved the use of either synchronized or non-synchronized sampling requiring
phase-locked sampling for synchronized sampling systems or equivalent phasor measurements
for non-synchronizing sampling systems The standard also defined a resynchronization method
for external time and sampling sources
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1261
P a g e | 5
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For steady state analysis it required that the phasor measurements followed the off-
nominal frequencies It also defined a convention for phasor representation independent from
window size The standard also requires phase compensations for delays internal to the PMU
It also defined the message format required for data reporting from the PMU organizedas data header and configuration frames and for commands received by the PMU
22 The IEEE C37118-2005 Synchrophasor Standard
This is the current PMU standard approved in December 2005 It addresses the definition
of a synchronized phasor time synchronization application of timetags method to verify
measurement compliance with the standard and message formats for communication with a
PMU [11]
This standard improved the time stamping method defined in the IEEE 1344-1995
Synchrophasor Standard [4] by redefining the phasor timetag as a group of three numbers a
second-of-century (SOC) count a fraction-of-second count and a time status value It also
allowed data format compatibility with other standards such as the IEC 61850 Standard
It defined the convention for phasor representation as an absolute phasor with a phase
locked to nominal frequency and synchronized to UTC time as shown in Figure 22
Figure 22 Convention for synchrophasor representation [IEEE Standard for Synchrophasors forPower Systems 2001] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1361
P a g e | 6
The Virginia Tech Calibration System copy 2011 Javier Fernandez
This standard specified the required phasor reporting rates for 50 Hz and 60 Hz as shown
in Table 21 the actual used rate being selected by the user
Table 21 Required PMU reporting rates [IEEE Standard for Synchrophasors for Power Systems2006] Illustrated under ldquoFair Userdquo copyright guidelines
It defined the steady-state condition where the magnitude frequency and phase of the
test signal remained constant during the time of measurement
This standard introduced the concept of total vector error (TVE) for quantifying phasor
measurement errors as defined in Figure 23
Figure 23 Phasor measurement process with TVE error detection criteria [IEEE Standard forSynchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1461
P a g e | 7
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The TVE is a comparison between a theoretical phasor X and an input phasor
measured by the PMU If a phase shift of ( is added to both X and the phasors would
rotate keeping the ratio between the magnitudes and the TVE constant
This standard also defined the error limits using the TVE concept for the recommended
steady-state compliance tests on the influence quantities shown in Table 32
The NIST developed the NIST PMU Calibration System for testing PMUs for
compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This steady-state
calibration test stand design is described in [9 11]
23 Need for a New Synchrophasor Standard
Some of the IEEE 1344-1995 Synchrophasor Standard [4] limitations were addressed in
the current standard The first standard defined the phasor requirements only at the zero
crossings or 1PPS second mark It did not specify any requirements for dynamic responses such
as measurement response time or accuracy under transient conditions The data format and the
serial type of interface required were not compatible with industry network communication
standards
The IEEE C37118-2005 Synchrophasor Standard [1] covers adequately most the steady-
state PMU characterization however there are limitations that will need to be addressed in the
new standard It does not specify frequency accuracy requirements Also lack of testing
procedures requirements in the current standard and unavailability of testing equipment are
major issues for PMU testing and calibration [5]
If the input frequency becomes off-nominal the mismatch induces a rotation between the
estimated phasor and the measured phasor causing the TVE to change inside the time window
Possible solutions are suggested in [12 13] including a modification to the standard to add a
TVE limit for the time window or a maximum frequency deviation for the compliance tests
Most importantly to support the increasing demand for high quality PMU applications on
large WAMS the current PMU standard needs to be further developed Future standards should
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1561
P a g e | 8
The Virginia Tech Calibration System copy 2011 Javier Fernandez
show a higher level of detail for dynamic PMU performance requirements testing procedures
and documentation that could guarantee homogeneous performance conformance among PMU
from different manufacturers
The NIST developed the NIST Dynamic Test System for testing PMU performance undertransient conditions and the use of this data for the development of new dynamic performance
requirements for PMUs This PMU dynamic characterization test stand design is described in [10
14 15]
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 461
iv
5 Dynamic Testing 35
51 Step Change response 35
511 Dynamic Magnitude Response 37
512 Dynamic Phase Response 39
513 Dynamic Frequency Response 43
6 Conclusions and Recommendations 48
References 49
Appendix A NI PXI-6682 Timing Module Technical Specifications 51
Appendix B Omicron CMC 156 EP Technical Specifications 52
Appendix C NI PXIe-6356 Data Acquisition Module Technical Specifications 53
Appendix D NI PXI-6733 Analog Output Module Technical Specifications 54
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 561
v
List of Figures
Figure 11 NIST phase measurement unit calibration system 3
Figure 12 Diagram of NIST dynamic test system 3 Figure 21 Convention for phasor representation 4
Figure 22 Convention for synchrophasor representation 5
Figure 23 Phasor measurement process with TVE error detection criteria 6
Figure 31 The Virginia Tech Calibration System requirements decomposition 9
Figure 32 The Virginia Tech Calibration System high level architectural depiction 16
Figure 33 Phase calibration of reference PMU with the 1PPS clock signal 23
Figure 41 MagTestRunNI VI front panel 25
Figure 42 MagTestRunNI VI block diagram 26
Figure 43 Voltage magnitude accuracy test results 27
Figure 44 PhaseTestRunNI VI front panel 28
Figure 45 PhaseTestRunNI VI block diagram 29 Figure 46 Phase accuracy test results 30
Figure 47 FreqTestRunNI VI front panel 32
Figure 48 FreqTestRunNI VI block diagram 33
Figure 49 Frequency accuracy test results 34
Figure 51 NI_DUT_Step_add VI block diagram 36
Figure 52 Run_Step_Test_on_DUTs_add VI front panel 37
Figure 53 Magnitude step change test signal 38
Figure 54 Magnitude step change test results 39
Figure 55 Phase step change test signal (-45˚) 40
Figure 56 Phases step change test signal (+45˚) 41
Figure 57 Phase step change test results (-45˚) 42
Figure 58 Phase step change test results (+45˚) 43
Figure 59 Frequency step change test signal (-2Hz) 44
Figure 510 Frequency step change test signal (+2Hz) 45
Figure 511 Frequency step change test results (-2Hz) 46
Figure 512 Frequency step change test results (+2Hz) 47
Figure B1 Omicron CMC 156 technical specifications 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 661
vi
List of Tables
Table 21 Required PMU reporting rates 6
Table 31 Hardware modules used in the NIST designs 11 Table 32 Influence quantities and allowable error limits for compliance levels 0-1 14
Table 33 Major processing component descriptions in the Virginia Tech Calibration System 16
Table 34 Hardware used in the Virginia Tech Calibration System steady-state design 17
Table 35 Software interface VIs in the Virginia Tech Calibration System 17
Table 36 Time source module accuracy comparison with the NIST designs 18
Table 37 Signal generation module accuracy comparison with the NIST designs 19
Table 38 Data acquisition module accuracy comparison with the NIST designs 19
Table 39 Signal processing module accuracy comparison with the NIST designs 20
Table 310 Synchronization source accuracy comparison with the NIST designs 21
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design 22
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design 22
Table A1 NI PXI-6682H synchronization accuracy 51
Table C1 NI PXIe-6356 technical specifications 53
Table D1 NI PXI-6733 technical specifications 54
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 761
vii
List of Acronyms
PMU Phasor measurement unit
NASPI North American Synchrophasor InitiativeNIST National institute of standards and technology
WAMPAC Wide-area monitoring protection and control
DOE Department of Energy
PSTT Performance and Standards Task Team
WECC Western Electricity Coordinating Council
CERTS Consortium for Electric Reliability Technology Solutions
EIPP Eastern Interconnection Phasor Project
SOC Second of Century
TVE Total vector error
GPS Global Positioning System
NI National Instruments
DUT Device under testVI Virtual Instrument
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 861
P a g e | 1
The Virginia Tech Calibration System copy 2011 Javier Fernandez
1 INTRODUCTION
The Phasor Measurement Unit (PMU) also known as synchrophasor takes time
synchronized measurements of voltage and current signals on a power grid This device was first
developed by researchers at Virginia Tech in Blacksburg VA in the late 1980rsquos PMU devicesare commercialized as a stand-alone unit or the PMU function can be integrated into a protective
relay or other device
PMU applications on wide-area monitoring protection and control (WAMPAC) systems
have gained worldwide acceptance since its emergence as commercial devices in the power
industry market in early 1990rsquos Brazil and China are currently deploying large WAMPAC
systems to control their power grids [2 3] The US Department Of Energy (DOE) as a response
to the 1996 and 2003 blackouts has sponsored improvements in the control of power grids that
involve the use of PMU-based WAMPAC systems
WAMPAC systems integrate information from selected local networks to a remote
location to minimize the widespread effects of large disturbances Most large PMU
implementations on wide-area monitoring networks use devices from various manufacturers
which present a challenge to ensure consistent phasor readings as they likely use different
measurement technologies For such systems WAMPAC system performance relies on the PMU
conformance to the same synchrophasor standard
In December 2005 the IEEE C37118-2005 Synchrophasor Standard [1] to replace the
IEEE 1344-1995(R2001) Synchrophasor Standard [4] developed in March 2001 These
standards define the synchrophasor phasor measurements in power grids for interoperability and
interfacing with associated equipment The IEEE Standard for Synchrophasors for Power
Systems C37118-2005 [1] covers adequately the PMU characterization under steady-state
conditions but falls short under transient conditions Consistent dynamic performance among
PMUs is of great importance for most current phasor applications
In 2007 the North America efforts in phasor technology were combined and the North
American Synchro Phasor Initiative (NASPI) emerged with the intent to coordinate phasor
activities in the entire North American grid The increased role for industry collaborations of the
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 961
P a g e | 2
The Virginia Tech Calibration System copy 2011 Javier Fernandez
NASPI working group and task teams has already extended to a more global collaboration of
industry best practices while the DOE continues to support phasor research Today there are
seven task teams focusing on various aspects of phasor activities[5]
Amongst the task teams is the Performance and Standards Task Team (PSTT) The PSTTis chartered to coordinate and act as liaison to standardization efforts and to determine consistent
and satisfactory performance of synchronized measurement devices and systems by creating
guidelines and reports in accordance with best practices Many of the PSTT members are active
in many international industry activities which help the Task Team members to coordinate the
development of phasor-related standards both within the NASPI as well as outside of North
America[5]
The PSTT team developed two complementary documents to the IEEE C37118 PMU
Testing Guide [6] and SynchroPhasor Accuracy Characterization [7]
This Guide describes performance and interoperability tests and calibration procedures
for PMUs used in the electric power industry to monitor the condition of the electric power grid
Conformance tests with the IEEE C37118-2005 Synchrophasor Standard and extended test
procedures to address the dynamic performance requirements not specified in the IEEE C37118-
2005 Synchrophasor Standard are included [1] This considers performance standards established
by the Western Electricity Coordinating Council (WECC) [8] Laboratory PMU test and
calibration procedures described[6]
To promote better test and measurement procedures for PMU test and calibration the
National Institute of Standards and Technology (NIST) in US has established a
SynchroMetrology Laboratory in support of the Consortium for Electric Reliability Technology
Solutions (CERTS) which sponsors the NASPI (was EIPP) The laboratory is established to
develop test and calibration methods to combine traditional waveform parameter metrology with
procedures to reference these values to a synchronized timing source such as UTC[3]
The NIST SynchroMetrology Laboratory developed two calibration systems as shown in
Figures 11 and 12 one for testing PMU for compliance with the IEEE C37118-2005
Synchrophasor Standard [1] and the other for dynamic characterization on PMUs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1061
P a g e | 3
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 11 NIST Phase Measurement Unit Calibration System [Stenbakken 2007] Illustrated
under ldquoFair Userdquo copyright guidelines
The purpose of developing the NIST Dynamic Test System includes the characterizationof commercial PMUs under dynamic power system conditions and the use of this data for the
development of new dynamic performance requirements for PMUs
Figure 12 Diagram of NIST Dynamic Test System [Stenbakken 2007] Illustrated under ldquoFair
Userdquo copyright guidelines
In this thesis project the NIST designs for steady-state calibration testing and dynamic
characterization of PMUs were implemented with new equipment the Virginia Tech Calibration
System This thesis provides an overview of the NIST designs and explains the required
modifications to integrate the new hardware
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1161
P a g e | 4
The Virginia Tech Calibration System copy 2011 Javier Fernandez
2 LITERATURE REVIEW
21 The IEEE 1344-1995 Synchrophasor Standard
This was the first PMU standard approved in December 1995 and reaffirmed in March
2005 It addresses synchronization of data sampling data-to-phasor conversions and formats for
timing input and phasor data output from a PMU [10]
The standard defined a precise method for time stamping data samples and phasor
measurements as shown in Figure 21 listed the requirements for the time synchronizing sources
and specified the allowed types of time input IRIG-B format 1 PPS and the high precision time
format
Figure 21 Convention for phasor representation [IEEE Standard for Synchrophasors for PowerSystems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
It approved the use of either synchronized or non-synchronized sampling requiring
phase-locked sampling for synchronized sampling systems or equivalent phasor measurements
for non-synchronizing sampling systems The standard also defined a resynchronization method
for external time and sampling sources
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1261
P a g e | 5
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For steady state analysis it required that the phasor measurements followed the off-
nominal frequencies It also defined a convention for phasor representation independent from
window size The standard also requires phase compensations for delays internal to the PMU
It also defined the message format required for data reporting from the PMU organizedas data header and configuration frames and for commands received by the PMU
22 The IEEE C37118-2005 Synchrophasor Standard
This is the current PMU standard approved in December 2005 It addresses the definition
of a synchronized phasor time synchronization application of timetags method to verify
measurement compliance with the standard and message formats for communication with a
PMU [11]
This standard improved the time stamping method defined in the IEEE 1344-1995
Synchrophasor Standard [4] by redefining the phasor timetag as a group of three numbers a
second-of-century (SOC) count a fraction-of-second count and a time status value It also
allowed data format compatibility with other standards such as the IEC 61850 Standard
It defined the convention for phasor representation as an absolute phasor with a phase
locked to nominal frequency and synchronized to UTC time as shown in Figure 22
Figure 22 Convention for synchrophasor representation [IEEE Standard for Synchrophasors forPower Systems 2001] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1361
P a g e | 6
The Virginia Tech Calibration System copy 2011 Javier Fernandez
This standard specified the required phasor reporting rates for 50 Hz and 60 Hz as shown
in Table 21 the actual used rate being selected by the user
Table 21 Required PMU reporting rates [IEEE Standard for Synchrophasors for Power Systems2006] Illustrated under ldquoFair Userdquo copyright guidelines
It defined the steady-state condition where the magnitude frequency and phase of the
test signal remained constant during the time of measurement
This standard introduced the concept of total vector error (TVE) for quantifying phasor
measurement errors as defined in Figure 23
Figure 23 Phasor measurement process with TVE error detection criteria [IEEE Standard forSynchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1461
P a g e | 7
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The TVE is a comparison between a theoretical phasor X and an input phasor
measured by the PMU If a phase shift of ( is added to both X and the phasors would
rotate keeping the ratio between the magnitudes and the TVE constant
This standard also defined the error limits using the TVE concept for the recommended
steady-state compliance tests on the influence quantities shown in Table 32
The NIST developed the NIST PMU Calibration System for testing PMUs for
compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This steady-state
calibration test stand design is described in [9 11]
23 Need for a New Synchrophasor Standard
Some of the IEEE 1344-1995 Synchrophasor Standard [4] limitations were addressed in
the current standard The first standard defined the phasor requirements only at the zero
crossings or 1PPS second mark It did not specify any requirements for dynamic responses such
as measurement response time or accuracy under transient conditions The data format and the
serial type of interface required were not compatible with industry network communication
standards
The IEEE C37118-2005 Synchrophasor Standard [1] covers adequately most the steady-
state PMU characterization however there are limitations that will need to be addressed in the
new standard It does not specify frequency accuracy requirements Also lack of testing
procedures requirements in the current standard and unavailability of testing equipment are
major issues for PMU testing and calibration [5]
If the input frequency becomes off-nominal the mismatch induces a rotation between the
estimated phasor and the measured phasor causing the TVE to change inside the time window
Possible solutions are suggested in [12 13] including a modification to the standard to add a
TVE limit for the time window or a maximum frequency deviation for the compliance tests
Most importantly to support the increasing demand for high quality PMU applications on
large WAMS the current PMU standard needs to be further developed Future standards should
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1561
P a g e | 8
The Virginia Tech Calibration System copy 2011 Javier Fernandez
show a higher level of detail for dynamic PMU performance requirements testing procedures
and documentation that could guarantee homogeneous performance conformance among PMU
from different manufacturers
The NIST developed the NIST Dynamic Test System for testing PMU performance undertransient conditions and the use of this data for the development of new dynamic performance
requirements for PMUs This PMU dynamic characterization test stand design is described in [10
14 15]
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 561
v
List of Figures
Figure 11 NIST phase measurement unit calibration system 3
Figure 12 Diagram of NIST dynamic test system 3 Figure 21 Convention for phasor representation 4
Figure 22 Convention for synchrophasor representation 5
Figure 23 Phasor measurement process with TVE error detection criteria 6
Figure 31 The Virginia Tech Calibration System requirements decomposition 9
Figure 32 The Virginia Tech Calibration System high level architectural depiction 16
Figure 33 Phase calibration of reference PMU with the 1PPS clock signal 23
Figure 41 MagTestRunNI VI front panel 25
Figure 42 MagTestRunNI VI block diagram 26
Figure 43 Voltage magnitude accuracy test results 27
Figure 44 PhaseTestRunNI VI front panel 28
Figure 45 PhaseTestRunNI VI block diagram 29 Figure 46 Phase accuracy test results 30
Figure 47 FreqTestRunNI VI front panel 32
Figure 48 FreqTestRunNI VI block diagram 33
Figure 49 Frequency accuracy test results 34
Figure 51 NI_DUT_Step_add VI block diagram 36
Figure 52 Run_Step_Test_on_DUTs_add VI front panel 37
Figure 53 Magnitude step change test signal 38
Figure 54 Magnitude step change test results 39
Figure 55 Phase step change test signal (-45˚) 40
Figure 56 Phases step change test signal (+45˚) 41
Figure 57 Phase step change test results (-45˚) 42
Figure 58 Phase step change test results (+45˚) 43
Figure 59 Frequency step change test signal (-2Hz) 44
Figure 510 Frequency step change test signal (+2Hz) 45
Figure 511 Frequency step change test results (-2Hz) 46
Figure 512 Frequency step change test results (+2Hz) 47
Figure B1 Omicron CMC 156 technical specifications 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 661
vi
List of Tables
Table 21 Required PMU reporting rates 6
Table 31 Hardware modules used in the NIST designs 11 Table 32 Influence quantities and allowable error limits for compliance levels 0-1 14
Table 33 Major processing component descriptions in the Virginia Tech Calibration System 16
Table 34 Hardware used in the Virginia Tech Calibration System steady-state design 17
Table 35 Software interface VIs in the Virginia Tech Calibration System 17
Table 36 Time source module accuracy comparison with the NIST designs 18
Table 37 Signal generation module accuracy comparison with the NIST designs 19
Table 38 Data acquisition module accuracy comparison with the NIST designs 19
Table 39 Signal processing module accuracy comparison with the NIST designs 20
Table 310 Synchronization source accuracy comparison with the NIST designs 21
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design 22
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design 22
Table A1 NI PXI-6682H synchronization accuracy 51
Table C1 NI PXIe-6356 technical specifications 53
Table D1 NI PXI-6733 technical specifications 54
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 761
vii
List of Acronyms
PMU Phasor measurement unit
NASPI North American Synchrophasor InitiativeNIST National institute of standards and technology
WAMPAC Wide-area monitoring protection and control
DOE Department of Energy
PSTT Performance and Standards Task Team
WECC Western Electricity Coordinating Council
CERTS Consortium for Electric Reliability Technology Solutions
EIPP Eastern Interconnection Phasor Project
SOC Second of Century
TVE Total vector error
GPS Global Positioning System
NI National Instruments
DUT Device under testVI Virtual Instrument
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 861
P a g e | 1
The Virginia Tech Calibration System copy 2011 Javier Fernandez
1 INTRODUCTION
The Phasor Measurement Unit (PMU) also known as synchrophasor takes time
synchronized measurements of voltage and current signals on a power grid This device was first
developed by researchers at Virginia Tech in Blacksburg VA in the late 1980rsquos PMU devicesare commercialized as a stand-alone unit or the PMU function can be integrated into a protective
relay or other device
PMU applications on wide-area monitoring protection and control (WAMPAC) systems
have gained worldwide acceptance since its emergence as commercial devices in the power
industry market in early 1990rsquos Brazil and China are currently deploying large WAMPAC
systems to control their power grids [2 3] The US Department Of Energy (DOE) as a response
to the 1996 and 2003 blackouts has sponsored improvements in the control of power grids that
involve the use of PMU-based WAMPAC systems
WAMPAC systems integrate information from selected local networks to a remote
location to minimize the widespread effects of large disturbances Most large PMU
implementations on wide-area monitoring networks use devices from various manufacturers
which present a challenge to ensure consistent phasor readings as they likely use different
measurement technologies For such systems WAMPAC system performance relies on the PMU
conformance to the same synchrophasor standard
In December 2005 the IEEE C37118-2005 Synchrophasor Standard [1] to replace the
IEEE 1344-1995(R2001) Synchrophasor Standard [4] developed in March 2001 These
standards define the synchrophasor phasor measurements in power grids for interoperability and
interfacing with associated equipment The IEEE Standard for Synchrophasors for Power
Systems C37118-2005 [1] covers adequately the PMU characterization under steady-state
conditions but falls short under transient conditions Consistent dynamic performance among
PMUs is of great importance for most current phasor applications
In 2007 the North America efforts in phasor technology were combined and the North
American Synchro Phasor Initiative (NASPI) emerged with the intent to coordinate phasor
activities in the entire North American grid The increased role for industry collaborations of the
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 961
P a g e | 2
The Virginia Tech Calibration System copy 2011 Javier Fernandez
NASPI working group and task teams has already extended to a more global collaboration of
industry best practices while the DOE continues to support phasor research Today there are
seven task teams focusing on various aspects of phasor activities[5]
Amongst the task teams is the Performance and Standards Task Team (PSTT) The PSTTis chartered to coordinate and act as liaison to standardization efforts and to determine consistent
and satisfactory performance of synchronized measurement devices and systems by creating
guidelines and reports in accordance with best practices Many of the PSTT members are active
in many international industry activities which help the Task Team members to coordinate the
development of phasor-related standards both within the NASPI as well as outside of North
America[5]
The PSTT team developed two complementary documents to the IEEE C37118 PMU
Testing Guide [6] and SynchroPhasor Accuracy Characterization [7]
This Guide describes performance and interoperability tests and calibration procedures
for PMUs used in the electric power industry to monitor the condition of the electric power grid
Conformance tests with the IEEE C37118-2005 Synchrophasor Standard and extended test
procedures to address the dynamic performance requirements not specified in the IEEE C37118-
2005 Synchrophasor Standard are included [1] This considers performance standards established
by the Western Electricity Coordinating Council (WECC) [8] Laboratory PMU test and
calibration procedures described[6]
To promote better test and measurement procedures for PMU test and calibration the
National Institute of Standards and Technology (NIST) in US has established a
SynchroMetrology Laboratory in support of the Consortium for Electric Reliability Technology
Solutions (CERTS) which sponsors the NASPI (was EIPP) The laboratory is established to
develop test and calibration methods to combine traditional waveform parameter metrology with
procedures to reference these values to a synchronized timing source such as UTC[3]
The NIST SynchroMetrology Laboratory developed two calibration systems as shown in
Figures 11 and 12 one for testing PMU for compliance with the IEEE C37118-2005
Synchrophasor Standard [1] and the other for dynamic characterization on PMUs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1061
P a g e | 3
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 11 NIST Phase Measurement Unit Calibration System [Stenbakken 2007] Illustrated
under ldquoFair Userdquo copyright guidelines
The purpose of developing the NIST Dynamic Test System includes the characterizationof commercial PMUs under dynamic power system conditions and the use of this data for the
development of new dynamic performance requirements for PMUs
Figure 12 Diagram of NIST Dynamic Test System [Stenbakken 2007] Illustrated under ldquoFair
Userdquo copyright guidelines
In this thesis project the NIST designs for steady-state calibration testing and dynamic
characterization of PMUs were implemented with new equipment the Virginia Tech Calibration
System This thesis provides an overview of the NIST designs and explains the required
modifications to integrate the new hardware
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1161
P a g e | 4
The Virginia Tech Calibration System copy 2011 Javier Fernandez
2 LITERATURE REVIEW
21 The IEEE 1344-1995 Synchrophasor Standard
This was the first PMU standard approved in December 1995 and reaffirmed in March
2005 It addresses synchronization of data sampling data-to-phasor conversions and formats for
timing input and phasor data output from a PMU [10]
The standard defined a precise method for time stamping data samples and phasor
measurements as shown in Figure 21 listed the requirements for the time synchronizing sources
and specified the allowed types of time input IRIG-B format 1 PPS and the high precision time
format
Figure 21 Convention for phasor representation [IEEE Standard for Synchrophasors for PowerSystems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
It approved the use of either synchronized or non-synchronized sampling requiring
phase-locked sampling for synchronized sampling systems or equivalent phasor measurements
for non-synchronizing sampling systems The standard also defined a resynchronization method
for external time and sampling sources
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1261
P a g e | 5
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For steady state analysis it required that the phasor measurements followed the off-
nominal frequencies It also defined a convention for phasor representation independent from
window size The standard also requires phase compensations for delays internal to the PMU
It also defined the message format required for data reporting from the PMU organizedas data header and configuration frames and for commands received by the PMU
22 The IEEE C37118-2005 Synchrophasor Standard
This is the current PMU standard approved in December 2005 It addresses the definition
of a synchronized phasor time synchronization application of timetags method to verify
measurement compliance with the standard and message formats for communication with a
PMU [11]
This standard improved the time stamping method defined in the IEEE 1344-1995
Synchrophasor Standard [4] by redefining the phasor timetag as a group of three numbers a
second-of-century (SOC) count a fraction-of-second count and a time status value It also
allowed data format compatibility with other standards such as the IEC 61850 Standard
It defined the convention for phasor representation as an absolute phasor with a phase
locked to nominal frequency and synchronized to UTC time as shown in Figure 22
Figure 22 Convention for synchrophasor representation [IEEE Standard for Synchrophasors forPower Systems 2001] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1361
P a g e | 6
The Virginia Tech Calibration System copy 2011 Javier Fernandez
This standard specified the required phasor reporting rates for 50 Hz and 60 Hz as shown
in Table 21 the actual used rate being selected by the user
Table 21 Required PMU reporting rates [IEEE Standard for Synchrophasors for Power Systems2006] Illustrated under ldquoFair Userdquo copyright guidelines
It defined the steady-state condition where the magnitude frequency and phase of the
test signal remained constant during the time of measurement
This standard introduced the concept of total vector error (TVE) for quantifying phasor
measurement errors as defined in Figure 23
Figure 23 Phasor measurement process with TVE error detection criteria [IEEE Standard forSynchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1461
P a g e | 7
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The TVE is a comparison between a theoretical phasor X and an input phasor
measured by the PMU If a phase shift of ( is added to both X and the phasors would
rotate keeping the ratio between the magnitudes and the TVE constant
This standard also defined the error limits using the TVE concept for the recommended
steady-state compliance tests on the influence quantities shown in Table 32
The NIST developed the NIST PMU Calibration System for testing PMUs for
compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This steady-state
calibration test stand design is described in [9 11]
23 Need for a New Synchrophasor Standard
Some of the IEEE 1344-1995 Synchrophasor Standard [4] limitations were addressed in
the current standard The first standard defined the phasor requirements only at the zero
crossings or 1PPS second mark It did not specify any requirements for dynamic responses such
as measurement response time or accuracy under transient conditions The data format and the
serial type of interface required were not compatible with industry network communication
standards
The IEEE C37118-2005 Synchrophasor Standard [1] covers adequately most the steady-
state PMU characterization however there are limitations that will need to be addressed in the
new standard It does not specify frequency accuracy requirements Also lack of testing
procedures requirements in the current standard and unavailability of testing equipment are
major issues for PMU testing and calibration [5]
If the input frequency becomes off-nominal the mismatch induces a rotation between the
estimated phasor and the measured phasor causing the TVE to change inside the time window
Possible solutions are suggested in [12 13] including a modification to the standard to add a
TVE limit for the time window or a maximum frequency deviation for the compliance tests
Most importantly to support the increasing demand for high quality PMU applications on
large WAMS the current PMU standard needs to be further developed Future standards should
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1561
P a g e | 8
The Virginia Tech Calibration System copy 2011 Javier Fernandez
show a higher level of detail for dynamic PMU performance requirements testing procedures
and documentation that could guarantee homogeneous performance conformance among PMU
from different manufacturers
The NIST developed the NIST Dynamic Test System for testing PMU performance undertransient conditions and the use of this data for the development of new dynamic performance
requirements for PMUs This PMU dynamic characterization test stand design is described in [10
14 15]
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 661
vi
List of Tables
Table 21 Required PMU reporting rates 6
Table 31 Hardware modules used in the NIST designs 11 Table 32 Influence quantities and allowable error limits for compliance levels 0-1 14
Table 33 Major processing component descriptions in the Virginia Tech Calibration System 16
Table 34 Hardware used in the Virginia Tech Calibration System steady-state design 17
Table 35 Software interface VIs in the Virginia Tech Calibration System 17
Table 36 Time source module accuracy comparison with the NIST designs 18
Table 37 Signal generation module accuracy comparison with the NIST designs 19
Table 38 Data acquisition module accuracy comparison with the NIST designs 19
Table 39 Signal processing module accuracy comparison with the NIST designs 20
Table 310 Synchronization source accuracy comparison with the NIST designs 21
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design 22
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design 22
Table A1 NI PXI-6682H synchronization accuracy 51
Table C1 NI PXIe-6356 technical specifications 53
Table D1 NI PXI-6733 technical specifications 54
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 761
vii
List of Acronyms
PMU Phasor measurement unit
NASPI North American Synchrophasor InitiativeNIST National institute of standards and technology
WAMPAC Wide-area monitoring protection and control
DOE Department of Energy
PSTT Performance and Standards Task Team
WECC Western Electricity Coordinating Council
CERTS Consortium for Electric Reliability Technology Solutions
EIPP Eastern Interconnection Phasor Project
SOC Second of Century
TVE Total vector error
GPS Global Positioning System
NI National Instruments
DUT Device under testVI Virtual Instrument
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 861
P a g e | 1
The Virginia Tech Calibration System copy 2011 Javier Fernandez
1 INTRODUCTION
The Phasor Measurement Unit (PMU) also known as synchrophasor takes time
synchronized measurements of voltage and current signals on a power grid This device was first
developed by researchers at Virginia Tech in Blacksburg VA in the late 1980rsquos PMU devicesare commercialized as a stand-alone unit or the PMU function can be integrated into a protective
relay or other device
PMU applications on wide-area monitoring protection and control (WAMPAC) systems
have gained worldwide acceptance since its emergence as commercial devices in the power
industry market in early 1990rsquos Brazil and China are currently deploying large WAMPAC
systems to control their power grids [2 3] The US Department Of Energy (DOE) as a response
to the 1996 and 2003 blackouts has sponsored improvements in the control of power grids that
involve the use of PMU-based WAMPAC systems
WAMPAC systems integrate information from selected local networks to a remote
location to minimize the widespread effects of large disturbances Most large PMU
implementations on wide-area monitoring networks use devices from various manufacturers
which present a challenge to ensure consistent phasor readings as they likely use different
measurement technologies For such systems WAMPAC system performance relies on the PMU
conformance to the same synchrophasor standard
In December 2005 the IEEE C37118-2005 Synchrophasor Standard [1] to replace the
IEEE 1344-1995(R2001) Synchrophasor Standard [4] developed in March 2001 These
standards define the synchrophasor phasor measurements in power grids for interoperability and
interfacing with associated equipment The IEEE Standard for Synchrophasors for Power
Systems C37118-2005 [1] covers adequately the PMU characterization under steady-state
conditions but falls short under transient conditions Consistent dynamic performance among
PMUs is of great importance for most current phasor applications
In 2007 the North America efforts in phasor technology were combined and the North
American Synchro Phasor Initiative (NASPI) emerged with the intent to coordinate phasor
activities in the entire North American grid The increased role for industry collaborations of the
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 961
P a g e | 2
The Virginia Tech Calibration System copy 2011 Javier Fernandez
NASPI working group and task teams has already extended to a more global collaboration of
industry best practices while the DOE continues to support phasor research Today there are
seven task teams focusing on various aspects of phasor activities[5]
Amongst the task teams is the Performance and Standards Task Team (PSTT) The PSTTis chartered to coordinate and act as liaison to standardization efforts and to determine consistent
and satisfactory performance of synchronized measurement devices and systems by creating
guidelines and reports in accordance with best practices Many of the PSTT members are active
in many international industry activities which help the Task Team members to coordinate the
development of phasor-related standards both within the NASPI as well as outside of North
America[5]
The PSTT team developed two complementary documents to the IEEE C37118 PMU
Testing Guide [6] and SynchroPhasor Accuracy Characterization [7]
This Guide describes performance and interoperability tests and calibration procedures
for PMUs used in the electric power industry to monitor the condition of the electric power grid
Conformance tests with the IEEE C37118-2005 Synchrophasor Standard and extended test
procedures to address the dynamic performance requirements not specified in the IEEE C37118-
2005 Synchrophasor Standard are included [1] This considers performance standards established
by the Western Electricity Coordinating Council (WECC) [8] Laboratory PMU test and
calibration procedures described[6]
To promote better test and measurement procedures for PMU test and calibration the
National Institute of Standards and Technology (NIST) in US has established a
SynchroMetrology Laboratory in support of the Consortium for Electric Reliability Technology
Solutions (CERTS) which sponsors the NASPI (was EIPP) The laboratory is established to
develop test and calibration methods to combine traditional waveform parameter metrology with
procedures to reference these values to a synchronized timing source such as UTC[3]
The NIST SynchroMetrology Laboratory developed two calibration systems as shown in
Figures 11 and 12 one for testing PMU for compliance with the IEEE C37118-2005
Synchrophasor Standard [1] and the other for dynamic characterization on PMUs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1061
P a g e | 3
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 11 NIST Phase Measurement Unit Calibration System [Stenbakken 2007] Illustrated
under ldquoFair Userdquo copyright guidelines
The purpose of developing the NIST Dynamic Test System includes the characterizationof commercial PMUs under dynamic power system conditions and the use of this data for the
development of new dynamic performance requirements for PMUs
Figure 12 Diagram of NIST Dynamic Test System [Stenbakken 2007] Illustrated under ldquoFair
Userdquo copyright guidelines
In this thesis project the NIST designs for steady-state calibration testing and dynamic
characterization of PMUs were implemented with new equipment the Virginia Tech Calibration
System This thesis provides an overview of the NIST designs and explains the required
modifications to integrate the new hardware
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1161
P a g e | 4
The Virginia Tech Calibration System copy 2011 Javier Fernandez
2 LITERATURE REVIEW
21 The IEEE 1344-1995 Synchrophasor Standard
This was the first PMU standard approved in December 1995 and reaffirmed in March
2005 It addresses synchronization of data sampling data-to-phasor conversions and formats for
timing input and phasor data output from a PMU [10]
The standard defined a precise method for time stamping data samples and phasor
measurements as shown in Figure 21 listed the requirements for the time synchronizing sources
and specified the allowed types of time input IRIG-B format 1 PPS and the high precision time
format
Figure 21 Convention for phasor representation [IEEE Standard for Synchrophasors for PowerSystems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
It approved the use of either synchronized or non-synchronized sampling requiring
phase-locked sampling for synchronized sampling systems or equivalent phasor measurements
for non-synchronizing sampling systems The standard also defined a resynchronization method
for external time and sampling sources
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1261
P a g e | 5
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For steady state analysis it required that the phasor measurements followed the off-
nominal frequencies It also defined a convention for phasor representation independent from
window size The standard also requires phase compensations for delays internal to the PMU
It also defined the message format required for data reporting from the PMU organizedas data header and configuration frames and for commands received by the PMU
22 The IEEE C37118-2005 Synchrophasor Standard
This is the current PMU standard approved in December 2005 It addresses the definition
of a synchronized phasor time synchronization application of timetags method to verify
measurement compliance with the standard and message formats for communication with a
PMU [11]
This standard improved the time stamping method defined in the IEEE 1344-1995
Synchrophasor Standard [4] by redefining the phasor timetag as a group of three numbers a
second-of-century (SOC) count a fraction-of-second count and a time status value It also
allowed data format compatibility with other standards such as the IEC 61850 Standard
It defined the convention for phasor representation as an absolute phasor with a phase
locked to nominal frequency and synchronized to UTC time as shown in Figure 22
Figure 22 Convention for synchrophasor representation [IEEE Standard for Synchrophasors forPower Systems 2001] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1361
P a g e | 6
The Virginia Tech Calibration System copy 2011 Javier Fernandez
This standard specified the required phasor reporting rates for 50 Hz and 60 Hz as shown
in Table 21 the actual used rate being selected by the user
Table 21 Required PMU reporting rates [IEEE Standard for Synchrophasors for Power Systems2006] Illustrated under ldquoFair Userdquo copyright guidelines
It defined the steady-state condition where the magnitude frequency and phase of the
test signal remained constant during the time of measurement
This standard introduced the concept of total vector error (TVE) for quantifying phasor
measurement errors as defined in Figure 23
Figure 23 Phasor measurement process with TVE error detection criteria [IEEE Standard forSynchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1461
P a g e | 7
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The TVE is a comparison between a theoretical phasor X and an input phasor
measured by the PMU If a phase shift of ( is added to both X and the phasors would
rotate keeping the ratio between the magnitudes and the TVE constant
This standard also defined the error limits using the TVE concept for the recommended
steady-state compliance tests on the influence quantities shown in Table 32
The NIST developed the NIST PMU Calibration System for testing PMUs for
compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This steady-state
calibration test stand design is described in [9 11]
23 Need for a New Synchrophasor Standard
Some of the IEEE 1344-1995 Synchrophasor Standard [4] limitations were addressed in
the current standard The first standard defined the phasor requirements only at the zero
crossings or 1PPS second mark It did not specify any requirements for dynamic responses such
as measurement response time or accuracy under transient conditions The data format and the
serial type of interface required were not compatible with industry network communication
standards
The IEEE C37118-2005 Synchrophasor Standard [1] covers adequately most the steady-
state PMU characterization however there are limitations that will need to be addressed in the
new standard It does not specify frequency accuracy requirements Also lack of testing
procedures requirements in the current standard and unavailability of testing equipment are
major issues for PMU testing and calibration [5]
If the input frequency becomes off-nominal the mismatch induces a rotation between the
estimated phasor and the measured phasor causing the TVE to change inside the time window
Possible solutions are suggested in [12 13] including a modification to the standard to add a
TVE limit for the time window or a maximum frequency deviation for the compliance tests
Most importantly to support the increasing demand for high quality PMU applications on
large WAMS the current PMU standard needs to be further developed Future standards should
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1561
P a g e | 8
The Virginia Tech Calibration System copy 2011 Javier Fernandez
show a higher level of detail for dynamic PMU performance requirements testing procedures
and documentation that could guarantee homogeneous performance conformance among PMU
from different manufacturers
The NIST developed the NIST Dynamic Test System for testing PMU performance undertransient conditions and the use of this data for the development of new dynamic performance
requirements for PMUs This PMU dynamic characterization test stand design is described in [10
14 15]
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 761
vii
List of Acronyms
PMU Phasor measurement unit
NASPI North American Synchrophasor InitiativeNIST National institute of standards and technology
WAMPAC Wide-area monitoring protection and control
DOE Department of Energy
PSTT Performance and Standards Task Team
WECC Western Electricity Coordinating Council
CERTS Consortium for Electric Reliability Technology Solutions
EIPP Eastern Interconnection Phasor Project
SOC Second of Century
TVE Total vector error
GPS Global Positioning System
NI National Instruments
DUT Device under testVI Virtual Instrument
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 861
P a g e | 1
The Virginia Tech Calibration System copy 2011 Javier Fernandez
1 INTRODUCTION
The Phasor Measurement Unit (PMU) also known as synchrophasor takes time
synchronized measurements of voltage and current signals on a power grid This device was first
developed by researchers at Virginia Tech in Blacksburg VA in the late 1980rsquos PMU devicesare commercialized as a stand-alone unit or the PMU function can be integrated into a protective
relay or other device
PMU applications on wide-area monitoring protection and control (WAMPAC) systems
have gained worldwide acceptance since its emergence as commercial devices in the power
industry market in early 1990rsquos Brazil and China are currently deploying large WAMPAC
systems to control their power grids [2 3] The US Department Of Energy (DOE) as a response
to the 1996 and 2003 blackouts has sponsored improvements in the control of power grids that
involve the use of PMU-based WAMPAC systems
WAMPAC systems integrate information from selected local networks to a remote
location to minimize the widespread effects of large disturbances Most large PMU
implementations on wide-area monitoring networks use devices from various manufacturers
which present a challenge to ensure consistent phasor readings as they likely use different
measurement technologies For such systems WAMPAC system performance relies on the PMU
conformance to the same synchrophasor standard
In December 2005 the IEEE C37118-2005 Synchrophasor Standard [1] to replace the
IEEE 1344-1995(R2001) Synchrophasor Standard [4] developed in March 2001 These
standards define the synchrophasor phasor measurements in power grids for interoperability and
interfacing with associated equipment The IEEE Standard for Synchrophasors for Power
Systems C37118-2005 [1] covers adequately the PMU characterization under steady-state
conditions but falls short under transient conditions Consistent dynamic performance among
PMUs is of great importance for most current phasor applications
In 2007 the North America efforts in phasor technology were combined and the North
American Synchro Phasor Initiative (NASPI) emerged with the intent to coordinate phasor
activities in the entire North American grid The increased role for industry collaborations of the
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 961
P a g e | 2
The Virginia Tech Calibration System copy 2011 Javier Fernandez
NASPI working group and task teams has already extended to a more global collaboration of
industry best practices while the DOE continues to support phasor research Today there are
seven task teams focusing on various aspects of phasor activities[5]
Amongst the task teams is the Performance and Standards Task Team (PSTT) The PSTTis chartered to coordinate and act as liaison to standardization efforts and to determine consistent
and satisfactory performance of synchronized measurement devices and systems by creating
guidelines and reports in accordance with best practices Many of the PSTT members are active
in many international industry activities which help the Task Team members to coordinate the
development of phasor-related standards both within the NASPI as well as outside of North
America[5]
The PSTT team developed two complementary documents to the IEEE C37118 PMU
Testing Guide [6] and SynchroPhasor Accuracy Characterization [7]
This Guide describes performance and interoperability tests and calibration procedures
for PMUs used in the electric power industry to monitor the condition of the electric power grid
Conformance tests with the IEEE C37118-2005 Synchrophasor Standard and extended test
procedures to address the dynamic performance requirements not specified in the IEEE C37118-
2005 Synchrophasor Standard are included [1] This considers performance standards established
by the Western Electricity Coordinating Council (WECC) [8] Laboratory PMU test and
calibration procedures described[6]
To promote better test and measurement procedures for PMU test and calibration the
National Institute of Standards and Technology (NIST) in US has established a
SynchroMetrology Laboratory in support of the Consortium for Electric Reliability Technology
Solutions (CERTS) which sponsors the NASPI (was EIPP) The laboratory is established to
develop test and calibration methods to combine traditional waveform parameter metrology with
procedures to reference these values to a synchronized timing source such as UTC[3]
The NIST SynchroMetrology Laboratory developed two calibration systems as shown in
Figures 11 and 12 one for testing PMU for compliance with the IEEE C37118-2005
Synchrophasor Standard [1] and the other for dynamic characterization on PMUs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1061
P a g e | 3
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 11 NIST Phase Measurement Unit Calibration System [Stenbakken 2007] Illustrated
under ldquoFair Userdquo copyright guidelines
The purpose of developing the NIST Dynamic Test System includes the characterizationof commercial PMUs under dynamic power system conditions and the use of this data for the
development of new dynamic performance requirements for PMUs
Figure 12 Diagram of NIST Dynamic Test System [Stenbakken 2007] Illustrated under ldquoFair
Userdquo copyright guidelines
In this thesis project the NIST designs for steady-state calibration testing and dynamic
characterization of PMUs were implemented with new equipment the Virginia Tech Calibration
System This thesis provides an overview of the NIST designs and explains the required
modifications to integrate the new hardware
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1161
P a g e | 4
The Virginia Tech Calibration System copy 2011 Javier Fernandez
2 LITERATURE REVIEW
21 The IEEE 1344-1995 Synchrophasor Standard
This was the first PMU standard approved in December 1995 and reaffirmed in March
2005 It addresses synchronization of data sampling data-to-phasor conversions and formats for
timing input and phasor data output from a PMU [10]
The standard defined a precise method for time stamping data samples and phasor
measurements as shown in Figure 21 listed the requirements for the time synchronizing sources
and specified the allowed types of time input IRIG-B format 1 PPS and the high precision time
format
Figure 21 Convention for phasor representation [IEEE Standard for Synchrophasors for PowerSystems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
It approved the use of either synchronized or non-synchronized sampling requiring
phase-locked sampling for synchronized sampling systems or equivalent phasor measurements
for non-synchronizing sampling systems The standard also defined a resynchronization method
for external time and sampling sources
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1261
P a g e | 5
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For steady state analysis it required that the phasor measurements followed the off-
nominal frequencies It also defined a convention for phasor representation independent from
window size The standard also requires phase compensations for delays internal to the PMU
It also defined the message format required for data reporting from the PMU organizedas data header and configuration frames and for commands received by the PMU
22 The IEEE C37118-2005 Synchrophasor Standard
This is the current PMU standard approved in December 2005 It addresses the definition
of a synchronized phasor time synchronization application of timetags method to verify
measurement compliance with the standard and message formats for communication with a
PMU [11]
This standard improved the time stamping method defined in the IEEE 1344-1995
Synchrophasor Standard [4] by redefining the phasor timetag as a group of three numbers a
second-of-century (SOC) count a fraction-of-second count and a time status value It also
allowed data format compatibility with other standards such as the IEC 61850 Standard
It defined the convention for phasor representation as an absolute phasor with a phase
locked to nominal frequency and synchronized to UTC time as shown in Figure 22
Figure 22 Convention for synchrophasor representation [IEEE Standard for Synchrophasors forPower Systems 2001] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1361
P a g e | 6
The Virginia Tech Calibration System copy 2011 Javier Fernandez
This standard specified the required phasor reporting rates for 50 Hz and 60 Hz as shown
in Table 21 the actual used rate being selected by the user
Table 21 Required PMU reporting rates [IEEE Standard for Synchrophasors for Power Systems2006] Illustrated under ldquoFair Userdquo copyright guidelines
It defined the steady-state condition where the magnitude frequency and phase of the
test signal remained constant during the time of measurement
This standard introduced the concept of total vector error (TVE) for quantifying phasor
measurement errors as defined in Figure 23
Figure 23 Phasor measurement process with TVE error detection criteria [IEEE Standard forSynchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1461
P a g e | 7
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The TVE is a comparison between a theoretical phasor X and an input phasor
measured by the PMU If a phase shift of ( is added to both X and the phasors would
rotate keeping the ratio between the magnitudes and the TVE constant
This standard also defined the error limits using the TVE concept for the recommended
steady-state compliance tests on the influence quantities shown in Table 32
The NIST developed the NIST PMU Calibration System for testing PMUs for
compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This steady-state
calibration test stand design is described in [9 11]
23 Need for a New Synchrophasor Standard
Some of the IEEE 1344-1995 Synchrophasor Standard [4] limitations were addressed in
the current standard The first standard defined the phasor requirements only at the zero
crossings or 1PPS second mark It did not specify any requirements for dynamic responses such
as measurement response time or accuracy under transient conditions The data format and the
serial type of interface required were not compatible with industry network communication
standards
The IEEE C37118-2005 Synchrophasor Standard [1] covers adequately most the steady-
state PMU characterization however there are limitations that will need to be addressed in the
new standard It does not specify frequency accuracy requirements Also lack of testing
procedures requirements in the current standard and unavailability of testing equipment are
major issues for PMU testing and calibration [5]
If the input frequency becomes off-nominal the mismatch induces a rotation between the
estimated phasor and the measured phasor causing the TVE to change inside the time window
Possible solutions are suggested in [12 13] including a modification to the standard to add a
TVE limit for the time window or a maximum frequency deviation for the compliance tests
Most importantly to support the increasing demand for high quality PMU applications on
large WAMS the current PMU standard needs to be further developed Future standards should
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1561
P a g e | 8
The Virginia Tech Calibration System copy 2011 Javier Fernandez
show a higher level of detail for dynamic PMU performance requirements testing procedures
and documentation that could guarantee homogeneous performance conformance among PMU
from different manufacturers
The NIST developed the NIST Dynamic Test System for testing PMU performance undertransient conditions and the use of this data for the development of new dynamic performance
requirements for PMUs This PMU dynamic characterization test stand design is described in [10
14 15]
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 861
P a g e | 1
The Virginia Tech Calibration System copy 2011 Javier Fernandez
1 INTRODUCTION
The Phasor Measurement Unit (PMU) also known as synchrophasor takes time
synchronized measurements of voltage and current signals on a power grid This device was first
developed by researchers at Virginia Tech in Blacksburg VA in the late 1980rsquos PMU devicesare commercialized as a stand-alone unit or the PMU function can be integrated into a protective
relay or other device
PMU applications on wide-area monitoring protection and control (WAMPAC) systems
have gained worldwide acceptance since its emergence as commercial devices in the power
industry market in early 1990rsquos Brazil and China are currently deploying large WAMPAC
systems to control their power grids [2 3] The US Department Of Energy (DOE) as a response
to the 1996 and 2003 blackouts has sponsored improvements in the control of power grids that
involve the use of PMU-based WAMPAC systems
WAMPAC systems integrate information from selected local networks to a remote
location to minimize the widespread effects of large disturbances Most large PMU
implementations on wide-area monitoring networks use devices from various manufacturers
which present a challenge to ensure consistent phasor readings as they likely use different
measurement technologies For such systems WAMPAC system performance relies on the PMU
conformance to the same synchrophasor standard
In December 2005 the IEEE C37118-2005 Synchrophasor Standard [1] to replace the
IEEE 1344-1995(R2001) Synchrophasor Standard [4] developed in March 2001 These
standards define the synchrophasor phasor measurements in power grids for interoperability and
interfacing with associated equipment The IEEE Standard for Synchrophasors for Power
Systems C37118-2005 [1] covers adequately the PMU characterization under steady-state
conditions but falls short under transient conditions Consistent dynamic performance among
PMUs is of great importance for most current phasor applications
In 2007 the North America efforts in phasor technology were combined and the North
American Synchro Phasor Initiative (NASPI) emerged with the intent to coordinate phasor
activities in the entire North American grid The increased role for industry collaborations of the
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 961
P a g e | 2
The Virginia Tech Calibration System copy 2011 Javier Fernandez
NASPI working group and task teams has already extended to a more global collaboration of
industry best practices while the DOE continues to support phasor research Today there are
seven task teams focusing on various aspects of phasor activities[5]
Amongst the task teams is the Performance and Standards Task Team (PSTT) The PSTTis chartered to coordinate and act as liaison to standardization efforts and to determine consistent
and satisfactory performance of synchronized measurement devices and systems by creating
guidelines and reports in accordance with best practices Many of the PSTT members are active
in many international industry activities which help the Task Team members to coordinate the
development of phasor-related standards both within the NASPI as well as outside of North
America[5]
The PSTT team developed two complementary documents to the IEEE C37118 PMU
Testing Guide [6] and SynchroPhasor Accuracy Characterization [7]
This Guide describes performance and interoperability tests and calibration procedures
for PMUs used in the electric power industry to monitor the condition of the electric power grid
Conformance tests with the IEEE C37118-2005 Synchrophasor Standard and extended test
procedures to address the dynamic performance requirements not specified in the IEEE C37118-
2005 Synchrophasor Standard are included [1] This considers performance standards established
by the Western Electricity Coordinating Council (WECC) [8] Laboratory PMU test and
calibration procedures described[6]
To promote better test and measurement procedures for PMU test and calibration the
National Institute of Standards and Technology (NIST) in US has established a
SynchroMetrology Laboratory in support of the Consortium for Electric Reliability Technology
Solutions (CERTS) which sponsors the NASPI (was EIPP) The laboratory is established to
develop test and calibration methods to combine traditional waveform parameter metrology with
procedures to reference these values to a synchronized timing source such as UTC[3]
The NIST SynchroMetrology Laboratory developed two calibration systems as shown in
Figures 11 and 12 one for testing PMU for compliance with the IEEE C37118-2005
Synchrophasor Standard [1] and the other for dynamic characterization on PMUs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1061
P a g e | 3
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 11 NIST Phase Measurement Unit Calibration System [Stenbakken 2007] Illustrated
under ldquoFair Userdquo copyright guidelines
The purpose of developing the NIST Dynamic Test System includes the characterizationof commercial PMUs under dynamic power system conditions and the use of this data for the
development of new dynamic performance requirements for PMUs
Figure 12 Diagram of NIST Dynamic Test System [Stenbakken 2007] Illustrated under ldquoFair
Userdquo copyright guidelines
In this thesis project the NIST designs for steady-state calibration testing and dynamic
characterization of PMUs were implemented with new equipment the Virginia Tech Calibration
System This thesis provides an overview of the NIST designs and explains the required
modifications to integrate the new hardware
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1161
P a g e | 4
The Virginia Tech Calibration System copy 2011 Javier Fernandez
2 LITERATURE REVIEW
21 The IEEE 1344-1995 Synchrophasor Standard
This was the first PMU standard approved in December 1995 and reaffirmed in March
2005 It addresses synchronization of data sampling data-to-phasor conversions and formats for
timing input and phasor data output from a PMU [10]
The standard defined a precise method for time stamping data samples and phasor
measurements as shown in Figure 21 listed the requirements for the time synchronizing sources
and specified the allowed types of time input IRIG-B format 1 PPS and the high precision time
format
Figure 21 Convention for phasor representation [IEEE Standard for Synchrophasors for PowerSystems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
It approved the use of either synchronized or non-synchronized sampling requiring
phase-locked sampling for synchronized sampling systems or equivalent phasor measurements
for non-synchronizing sampling systems The standard also defined a resynchronization method
for external time and sampling sources
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1261
P a g e | 5
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For steady state analysis it required that the phasor measurements followed the off-
nominal frequencies It also defined a convention for phasor representation independent from
window size The standard also requires phase compensations for delays internal to the PMU
It also defined the message format required for data reporting from the PMU organizedas data header and configuration frames and for commands received by the PMU
22 The IEEE C37118-2005 Synchrophasor Standard
This is the current PMU standard approved in December 2005 It addresses the definition
of a synchronized phasor time synchronization application of timetags method to verify
measurement compliance with the standard and message formats for communication with a
PMU [11]
This standard improved the time stamping method defined in the IEEE 1344-1995
Synchrophasor Standard [4] by redefining the phasor timetag as a group of three numbers a
second-of-century (SOC) count a fraction-of-second count and a time status value It also
allowed data format compatibility with other standards such as the IEC 61850 Standard
It defined the convention for phasor representation as an absolute phasor with a phase
locked to nominal frequency and synchronized to UTC time as shown in Figure 22
Figure 22 Convention for synchrophasor representation [IEEE Standard for Synchrophasors forPower Systems 2001] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1361
P a g e | 6
The Virginia Tech Calibration System copy 2011 Javier Fernandez
This standard specified the required phasor reporting rates for 50 Hz and 60 Hz as shown
in Table 21 the actual used rate being selected by the user
Table 21 Required PMU reporting rates [IEEE Standard for Synchrophasors for Power Systems2006] Illustrated under ldquoFair Userdquo copyright guidelines
It defined the steady-state condition where the magnitude frequency and phase of the
test signal remained constant during the time of measurement
This standard introduced the concept of total vector error (TVE) for quantifying phasor
measurement errors as defined in Figure 23
Figure 23 Phasor measurement process with TVE error detection criteria [IEEE Standard forSynchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1461
P a g e | 7
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The TVE is a comparison between a theoretical phasor X and an input phasor
measured by the PMU If a phase shift of ( is added to both X and the phasors would
rotate keeping the ratio between the magnitudes and the TVE constant
This standard also defined the error limits using the TVE concept for the recommended
steady-state compliance tests on the influence quantities shown in Table 32
The NIST developed the NIST PMU Calibration System for testing PMUs for
compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This steady-state
calibration test stand design is described in [9 11]
23 Need for a New Synchrophasor Standard
Some of the IEEE 1344-1995 Synchrophasor Standard [4] limitations were addressed in
the current standard The first standard defined the phasor requirements only at the zero
crossings or 1PPS second mark It did not specify any requirements for dynamic responses such
as measurement response time or accuracy under transient conditions The data format and the
serial type of interface required were not compatible with industry network communication
standards
The IEEE C37118-2005 Synchrophasor Standard [1] covers adequately most the steady-
state PMU characterization however there are limitations that will need to be addressed in the
new standard It does not specify frequency accuracy requirements Also lack of testing
procedures requirements in the current standard and unavailability of testing equipment are
major issues for PMU testing and calibration [5]
If the input frequency becomes off-nominal the mismatch induces a rotation between the
estimated phasor and the measured phasor causing the TVE to change inside the time window
Possible solutions are suggested in [12 13] including a modification to the standard to add a
TVE limit for the time window or a maximum frequency deviation for the compliance tests
Most importantly to support the increasing demand for high quality PMU applications on
large WAMS the current PMU standard needs to be further developed Future standards should
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1561
P a g e | 8
The Virginia Tech Calibration System copy 2011 Javier Fernandez
show a higher level of detail for dynamic PMU performance requirements testing procedures
and documentation that could guarantee homogeneous performance conformance among PMU
from different manufacturers
The NIST developed the NIST Dynamic Test System for testing PMU performance undertransient conditions and the use of this data for the development of new dynamic performance
requirements for PMUs This PMU dynamic characterization test stand design is described in [10
14 15]
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 961
P a g e | 2
The Virginia Tech Calibration System copy 2011 Javier Fernandez
NASPI working group and task teams has already extended to a more global collaboration of
industry best practices while the DOE continues to support phasor research Today there are
seven task teams focusing on various aspects of phasor activities[5]
Amongst the task teams is the Performance and Standards Task Team (PSTT) The PSTTis chartered to coordinate and act as liaison to standardization efforts and to determine consistent
and satisfactory performance of synchronized measurement devices and systems by creating
guidelines and reports in accordance with best practices Many of the PSTT members are active
in many international industry activities which help the Task Team members to coordinate the
development of phasor-related standards both within the NASPI as well as outside of North
America[5]
The PSTT team developed two complementary documents to the IEEE C37118 PMU
Testing Guide [6] and SynchroPhasor Accuracy Characterization [7]
This Guide describes performance and interoperability tests and calibration procedures
for PMUs used in the electric power industry to monitor the condition of the electric power grid
Conformance tests with the IEEE C37118-2005 Synchrophasor Standard and extended test
procedures to address the dynamic performance requirements not specified in the IEEE C37118-
2005 Synchrophasor Standard are included [1] This considers performance standards established
by the Western Electricity Coordinating Council (WECC) [8] Laboratory PMU test and
calibration procedures described[6]
To promote better test and measurement procedures for PMU test and calibration the
National Institute of Standards and Technology (NIST) in US has established a
SynchroMetrology Laboratory in support of the Consortium for Electric Reliability Technology
Solutions (CERTS) which sponsors the NASPI (was EIPP) The laboratory is established to
develop test and calibration methods to combine traditional waveform parameter metrology with
procedures to reference these values to a synchronized timing source such as UTC[3]
The NIST SynchroMetrology Laboratory developed two calibration systems as shown in
Figures 11 and 12 one for testing PMU for compliance with the IEEE C37118-2005
Synchrophasor Standard [1] and the other for dynamic characterization on PMUs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1061
P a g e | 3
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 11 NIST Phase Measurement Unit Calibration System [Stenbakken 2007] Illustrated
under ldquoFair Userdquo copyright guidelines
The purpose of developing the NIST Dynamic Test System includes the characterizationof commercial PMUs under dynamic power system conditions and the use of this data for the
development of new dynamic performance requirements for PMUs
Figure 12 Diagram of NIST Dynamic Test System [Stenbakken 2007] Illustrated under ldquoFair
Userdquo copyright guidelines
In this thesis project the NIST designs for steady-state calibration testing and dynamic
characterization of PMUs were implemented with new equipment the Virginia Tech Calibration
System This thesis provides an overview of the NIST designs and explains the required
modifications to integrate the new hardware
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1161
P a g e | 4
The Virginia Tech Calibration System copy 2011 Javier Fernandez
2 LITERATURE REVIEW
21 The IEEE 1344-1995 Synchrophasor Standard
This was the first PMU standard approved in December 1995 and reaffirmed in March
2005 It addresses synchronization of data sampling data-to-phasor conversions and formats for
timing input and phasor data output from a PMU [10]
The standard defined a precise method for time stamping data samples and phasor
measurements as shown in Figure 21 listed the requirements for the time synchronizing sources
and specified the allowed types of time input IRIG-B format 1 PPS and the high precision time
format
Figure 21 Convention for phasor representation [IEEE Standard for Synchrophasors for PowerSystems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
It approved the use of either synchronized or non-synchronized sampling requiring
phase-locked sampling for synchronized sampling systems or equivalent phasor measurements
for non-synchronizing sampling systems The standard also defined a resynchronization method
for external time and sampling sources
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1261
P a g e | 5
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For steady state analysis it required that the phasor measurements followed the off-
nominal frequencies It also defined a convention for phasor representation independent from
window size The standard also requires phase compensations for delays internal to the PMU
It also defined the message format required for data reporting from the PMU organizedas data header and configuration frames and for commands received by the PMU
22 The IEEE C37118-2005 Synchrophasor Standard
This is the current PMU standard approved in December 2005 It addresses the definition
of a synchronized phasor time synchronization application of timetags method to verify
measurement compliance with the standard and message formats for communication with a
PMU [11]
This standard improved the time stamping method defined in the IEEE 1344-1995
Synchrophasor Standard [4] by redefining the phasor timetag as a group of three numbers a
second-of-century (SOC) count a fraction-of-second count and a time status value It also
allowed data format compatibility with other standards such as the IEC 61850 Standard
It defined the convention for phasor representation as an absolute phasor with a phase
locked to nominal frequency and synchronized to UTC time as shown in Figure 22
Figure 22 Convention for synchrophasor representation [IEEE Standard for Synchrophasors forPower Systems 2001] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1361
P a g e | 6
The Virginia Tech Calibration System copy 2011 Javier Fernandez
This standard specified the required phasor reporting rates for 50 Hz and 60 Hz as shown
in Table 21 the actual used rate being selected by the user
Table 21 Required PMU reporting rates [IEEE Standard for Synchrophasors for Power Systems2006] Illustrated under ldquoFair Userdquo copyright guidelines
It defined the steady-state condition where the magnitude frequency and phase of the
test signal remained constant during the time of measurement
This standard introduced the concept of total vector error (TVE) for quantifying phasor
measurement errors as defined in Figure 23
Figure 23 Phasor measurement process with TVE error detection criteria [IEEE Standard forSynchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1461
P a g e | 7
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The TVE is a comparison between a theoretical phasor X and an input phasor
measured by the PMU If a phase shift of ( is added to both X and the phasors would
rotate keeping the ratio between the magnitudes and the TVE constant
This standard also defined the error limits using the TVE concept for the recommended
steady-state compliance tests on the influence quantities shown in Table 32
The NIST developed the NIST PMU Calibration System for testing PMUs for
compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This steady-state
calibration test stand design is described in [9 11]
23 Need for a New Synchrophasor Standard
Some of the IEEE 1344-1995 Synchrophasor Standard [4] limitations were addressed in
the current standard The first standard defined the phasor requirements only at the zero
crossings or 1PPS second mark It did not specify any requirements for dynamic responses such
as measurement response time or accuracy under transient conditions The data format and the
serial type of interface required were not compatible with industry network communication
standards
The IEEE C37118-2005 Synchrophasor Standard [1] covers adequately most the steady-
state PMU characterization however there are limitations that will need to be addressed in the
new standard It does not specify frequency accuracy requirements Also lack of testing
procedures requirements in the current standard and unavailability of testing equipment are
major issues for PMU testing and calibration [5]
If the input frequency becomes off-nominal the mismatch induces a rotation between the
estimated phasor and the measured phasor causing the TVE to change inside the time window
Possible solutions are suggested in [12 13] including a modification to the standard to add a
TVE limit for the time window or a maximum frequency deviation for the compliance tests
Most importantly to support the increasing demand for high quality PMU applications on
large WAMS the current PMU standard needs to be further developed Future standards should
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1561
P a g e | 8
The Virginia Tech Calibration System copy 2011 Javier Fernandez
show a higher level of detail for dynamic PMU performance requirements testing procedures
and documentation that could guarantee homogeneous performance conformance among PMU
from different manufacturers
The NIST developed the NIST Dynamic Test System for testing PMU performance undertransient conditions and the use of this data for the development of new dynamic performance
requirements for PMUs This PMU dynamic characterization test stand design is described in [10
14 15]
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1061
P a g e | 3
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 11 NIST Phase Measurement Unit Calibration System [Stenbakken 2007] Illustrated
under ldquoFair Userdquo copyright guidelines
The purpose of developing the NIST Dynamic Test System includes the characterizationof commercial PMUs under dynamic power system conditions and the use of this data for the
development of new dynamic performance requirements for PMUs
Figure 12 Diagram of NIST Dynamic Test System [Stenbakken 2007] Illustrated under ldquoFair
Userdquo copyright guidelines
In this thesis project the NIST designs for steady-state calibration testing and dynamic
characterization of PMUs were implemented with new equipment the Virginia Tech Calibration
System This thesis provides an overview of the NIST designs and explains the required
modifications to integrate the new hardware
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1161
P a g e | 4
The Virginia Tech Calibration System copy 2011 Javier Fernandez
2 LITERATURE REVIEW
21 The IEEE 1344-1995 Synchrophasor Standard
This was the first PMU standard approved in December 1995 and reaffirmed in March
2005 It addresses synchronization of data sampling data-to-phasor conversions and formats for
timing input and phasor data output from a PMU [10]
The standard defined a precise method for time stamping data samples and phasor
measurements as shown in Figure 21 listed the requirements for the time synchronizing sources
and specified the allowed types of time input IRIG-B format 1 PPS and the high precision time
format
Figure 21 Convention for phasor representation [IEEE Standard for Synchrophasors for PowerSystems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
It approved the use of either synchronized or non-synchronized sampling requiring
phase-locked sampling for synchronized sampling systems or equivalent phasor measurements
for non-synchronizing sampling systems The standard also defined a resynchronization method
for external time and sampling sources
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1261
P a g e | 5
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For steady state analysis it required that the phasor measurements followed the off-
nominal frequencies It also defined a convention for phasor representation independent from
window size The standard also requires phase compensations for delays internal to the PMU
It also defined the message format required for data reporting from the PMU organizedas data header and configuration frames and for commands received by the PMU
22 The IEEE C37118-2005 Synchrophasor Standard
This is the current PMU standard approved in December 2005 It addresses the definition
of a synchronized phasor time synchronization application of timetags method to verify
measurement compliance with the standard and message formats for communication with a
PMU [11]
This standard improved the time stamping method defined in the IEEE 1344-1995
Synchrophasor Standard [4] by redefining the phasor timetag as a group of three numbers a
second-of-century (SOC) count a fraction-of-second count and a time status value It also
allowed data format compatibility with other standards such as the IEC 61850 Standard
It defined the convention for phasor representation as an absolute phasor with a phase
locked to nominal frequency and synchronized to UTC time as shown in Figure 22
Figure 22 Convention for synchrophasor representation [IEEE Standard for Synchrophasors forPower Systems 2001] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1361
P a g e | 6
The Virginia Tech Calibration System copy 2011 Javier Fernandez
This standard specified the required phasor reporting rates for 50 Hz and 60 Hz as shown
in Table 21 the actual used rate being selected by the user
Table 21 Required PMU reporting rates [IEEE Standard for Synchrophasors for Power Systems2006] Illustrated under ldquoFair Userdquo copyright guidelines
It defined the steady-state condition where the magnitude frequency and phase of the
test signal remained constant during the time of measurement
This standard introduced the concept of total vector error (TVE) for quantifying phasor
measurement errors as defined in Figure 23
Figure 23 Phasor measurement process with TVE error detection criteria [IEEE Standard forSynchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1461
P a g e | 7
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The TVE is a comparison between a theoretical phasor X and an input phasor
measured by the PMU If a phase shift of ( is added to both X and the phasors would
rotate keeping the ratio between the magnitudes and the TVE constant
This standard also defined the error limits using the TVE concept for the recommended
steady-state compliance tests on the influence quantities shown in Table 32
The NIST developed the NIST PMU Calibration System for testing PMUs for
compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This steady-state
calibration test stand design is described in [9 11]
23 Need for a New Synchrophasor Standard
Some of the IEEE 1344-1995 Synchrophasor Standard [4] limitations were addressed in
the current standard The first standard defined the phasor requirements only at the zero
crossings or 1PPS second mark It did not specify any requirements for dynamic responses such
as measurement response time or accuracy under transient conditions The data format and the
serial type of interface required were not compatible with industry network communication
standards
The IEEE C37118-2005 Synchrophasor Standard [1] covers adequately most the steady-
state PMU characterization however there are limitations that will need to be addressed in the
new standard It does not specify frequency accuracy requirements Also lack of testing
procedures requirements in the current standard and unavailability of testing equipment are
major issues for PMU testing and calibration [5]
If the input frequency becomes off-nominal the mismatch induces a rotation between the
estimated phasor and the measured phasor causing the TVE to change inside the time window
Possible solutions are suggested in [12 13] including a modification to the standard to add a
TVE limit for the time window or a maximum frequency deviation for the compliance tests
Most importantly to support the increasing demand for high quality PMU applications on
large WAMS the current PMU standard needs to be further developed Future standards should
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1561
P a g e | 8
The Virginia Tech Calibration System copy 2011 Javier Fernandez
show a higher level of detail for dynamic PMU performance requirements testing procedures
and documentation that could guarantee homogeneous performance conformance among PMU
from different manufacturers
The NIST developed the NIST Dynamic Test System for testing PMU performance undertransient conditions and the use of this data for the development of new dynamic performance
requirements for PMUs This PMU dynamic characterization test stand design is described in [10
14 15]
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1161
P a g e | 4
The Virginia Tech Calibration System copy 2011 Javier Fernandez
2 LITERATURE REVIEW
21 The IEEE 1344-1995 Synchrophasor Standard
This was the first PMU standard approved in December 1995 and reaffirmed in March
2005 It addresses synchronization of data sampling data-to-phasor conversions and formats for
timing input and phasor data output from a PMU [10]
The standard defined a precise method for time stamping data samples and phasor
measurements as shown in Figure 21 listed the requirements for the time synchronizing sources
and specified the allowed types of time input IRIG-B format 1 PPS and the high precision time
format
Figure 21 Convention for phasor representation [IEEE Standard for Synchrophasors for PowerSystems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
It approved the use of either synchronized or non-synchronized sampling requiring
phase-locked sampling for synchronized sampling systems or equivalent phasor measurements
for non-synchronizing sampling systems The standard also defined a resynchronization method
for external time and sampling sources
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1261
P a g e | 5
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For steady state analysis it required that the phasor measurements followed the off-
nominal frequencies It also defined a convention for phasor representation independent from
window size The standard also requires phase compensations for delays internal to the PMU
It also defined the message format required for data reporting from the PMU organizedas data header and configuration frames and for commands received by the PMU
22 The IEEE C37118-2005 Synchrophasor Standard
This is the current PMU standard approved in December 2005 It addresses the definition
of a synchronized phasor time synchronization application of timetags method to verify
measurement compliance with the standard and message formats for communication with a
PMU [11]
This standard improved the time stamping method defined in the IEEE 1344-1995
Synchrophasor Standard [4] by redefining the phasor timetag as a group of three numbers a
second-of-century (SOC) count a fraction-of-second count and a time status value It also
allowed data format compatibility with other standards such as the IEC 61850 Standard
It defined the convention for phasor representation as an absolute phasor with a phase
locked to nominal frequency and synchronized to UTC time as shown in Figure 22
Figure 22 Convention for synchrophasor representation [IEEE Standard for Synchrophasors forPower Systems 2001] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1361
P a g e | 6
The Virginia Tech Calibration System copy 2011 Javier Fernandez
This standard specified the required phasor reporting rates for 50 Hz and 60 Hz as shown
in Table 21 the actual used rate being selected by the user
Table 21 Required PMU reporting rates [IEEE Standard for Synchrophasors for Power Systems2006] Illustrated under ldquoFair Userdquo copyright guidelines
It defined the steady-state condition where the magnitude frequency and phase of the
test signal remained constant during the time of measurement
This standard introduced the concept of total vector error (TVE) for quantifying phasor
measurement errors as defined in Figure 23
Figure 23 Phasor measurement process with TVE error detection criteria [IEEE Standard forSynchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1461
P a g e | 7
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The TVE is a comparison between a theoretical phasor X and an input phasor
measured by the PMU If a phase shift of ( is added to both X and the phasors would
rotate keeping the ratio between the magnitudes and the TVE constant
This standard also defined the error limits using the TVE concept for the recommended
steady-state compliance tests on the influence quantities shown in Table 32
The NIST developed the NIST PMU Calibration System for testing PMUs for
compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This steady-state
calibration test stand design is described in [9 11]
23 Need for a New Synchrophasor Standard
Some of the IEEE 1344-1995 Synchrophasor Standard [4] limitations were addressed in
the current standard The first standard defined the phasor requirements only at the zero
crossings or 1PPS second mark It did not specify any requirements for dynamic responses such
as measurement response time or accuracy under transient conditions The data format and the
serial type of interface required were not compatible with industry network communication
standards
The IEEE C37118-2005 Synchrophasor Standard [1] covers adequately most the steady-
state PMU characterization however there are limitations that will need to be addressed in the
new standard It does not specify frequency accuracy requirements Also lack of testing
procedures requirements in the current standard and unavailability of testing equipment are
major issues for PMU testing and calibration [5]
If the input frequency becomes off-nominal the mismatch induces a rotation between the
estimated phasor and the measured phasor causing the TVE to change inside the time window
Possible solutions are suggested in [12 13] including a modification to the standard to add a
TVE limit for the time window or a maximum frequency deviation for the compliance tests
Most importantly to support the increasing demand for high quality PMU applications on
large WAMS the current PMU standard needs to be further developed Future standards should
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1561
P a g e | 8
The Virginia Tech Calibration System copy 2011 Javier Fernandez
show a higher level of detail for dynamic PMU performance requirements testing procedures
and documentation that could guarantee homogeneous performance conformance among PMU
from different manufacturers
The NIST developed the NIST Dynamic Test System for testing PMU performance undertransient conditions and the use of this data for the development of new dynamic performance
requirements for PMUs This PMU dynamic characterization test stand design is described in [10
14 15]
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1261
P a g e | 5
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For steady state analysis it required that the phasor measurements followed the off-
nominal frequencies It also defined a convention for phasor representation independent from
window size The standard also requires phase compensations for delays internal to the PMU
It also defined the message format required for data reporting from the PMU organizedas data header and configuration frames and for commands received by the PMU
22 The IEEE C37118-2005 Synchrophasor Standard
This is the current PMU standard approved in December 2005 It addresses the definition
of a synchronized phasor time synchronization application of timetags method to verify
measurement compliance with the standard and message formats for communication with a
PMU [11]
This standard improved the time stamping method defined in the IEEE 1344-1995
Synchrophasor Standard [4] by redefining the phasor timetag as a group of three numbers a
second-of-century (SOC) count a fraction-of-second count and a time status value It also
allowed data format compatibility with other standards such as the IEC 61850 Standard
It defined the convention for phasor representation as an absolute phasor with a phase
locked to nominal frequency and synchronized to UTC time as shown in Figure 22
Figure 22 Convention for synchrophasor representation [IEEE Standard for Synchrophasors forPower Systems 2001] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1361
P a g e | 6
The Virginia Tech Calibration System copy 2011 Javier Fernandez
This standard specified the required phasor reporting rates for 50 Hz and 60 Hz as shown
in Table 21 the actual used rate being selected by the user
Table 21 Required PMU reporting rates [IEEE Standard for Synchrophasors for Power Systems2006] Illustrated under ldquoFair Userdquo copyright guidelines
It defined the steady-state condition where the magnitude frequency and phase of the
test signal remained constant during the time of measurement
This standard introduced the concept of total vector error (TVE) for quantifying phasor
measurement errors as defined in Figure 23
Figure 23 Phasor measurement process with TVE error detection criteria [IEEE Standard forSynchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1461
P a g e | 7
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The TVE is a comparison between a theoretical phasor X and an input phasor
measured by the PMU If a phase shift of ( is added to both X and the phasors would
rotate keeping the ratio between the magnitudes and the TVE constant
This standard also defined the error limits using the TVE concept for the recommended
steady-state compliance tests on the influence quantities shown in Table 32
The NIST developed the NIST PMU Calibration System for testing PMUs for
compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This steady-state
calibration test stand design is described in [9 11]
23 Need for a New Synchrophasor Standard
Some of the IEEE 1344-1995 Synchrophasor Standard [4] limitations were addressed in
the current standard The first standard defined the phasor requirements only at the zero
crossings or 1PPS second mark It did not specify any requirements for dynamic responses such
as measurement response time or accuracy under transient conditions The data format and the
serial type of interface required were not compatible with industry network communication
standards
The IEEE C37118-2005 Synchrophasor Standard [1] covers adequately most the steady-
state PMU characterization however there are limitations that will need to be addressed in the
new standard It does not specify frequency accuracy requirements Also lack of testing
procedures requirements in the current standard and unavailability of testing equipment are
major issues for PMU testing and calibration [5]
If the input frequency becomes off-nominal the mismatch induces a rotation between the
estimated phasor and the measured phasor causing the TVE to change inside the time window
Possible solutions are suggested in [12 13] including a modification to the standard to add a
TVE limit for the time window or a maximum frequency deviation for the compliance tests
Most importantly to support the increasing demand for high quality PMU applications on
large WAMS the current PMU standard needs to be further developed Future standards should
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1561
P a g e | 8
The Virginia Tech Calibration System copy 2011 Javier Fernandez
show a higher level of detail for dynamic PMU performance requirements testing procedures
and documentation that could guarantee homogeneous performance conformance among PMU
from different manufacturers
The NIST developed the NIST Dynamic Test System for testing PMU performance undertransient conditions and the use of this data for the development of new dynamic performance
requirements for PMUs This PMU dynamic characterization test stand design is described in [10
14 15]
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1361
P a g e | 6
The Virginia Tech Calibration System copy 2011 Javier Fernandez
This standard specified the required phasor reporting rates for 50 Hz and 60 Hz as shown
in Table 21 the actual used rate being selected by the user
Table 21 Required PMU reporting rates [IEEE Standard for Synchrophasors for Power Systems2006] Illustrated under ldquoFair Userdquo copyright guidelines
It defined the steady-state condition where the magnitude frequency and phase of the
test signal remained constant during the time of measurement
This standard introduced the concept of total vector error (TVE) for quantifying phasor
measurement errors as defined in Figure 23
Figure 23 Phasor measurement process with TVE error detection criteria [IEEE Standard forSynchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1461
P a g e | 7
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The TVE is a comparison between a theoretical phasor X and an input phasor
measured by the PMU If a phase shift of ( is added to both X and the phasors would
rotate keeping the ratio between the magnitudes and the TVE constant
This standard also defined the error limits using the TVE concept for the recommended
steady-state compliance tests on the influence quantities shown in Table 32
The NIST developed the NIST PMU Calibration System for testing PMUs for
compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This steady-state
calibration test stand design is described in [9 11]
23 Need for a New Synchrophasor Standard
Some of the IEEE 1344-1995 Synchrophasor Standard [4] limitations were addressed in
the current standard The first standard defined the phasor requirements only at the zero
crossings or 1PPS second mark It did not specify any requirements for dynamic responses such
as measurement response time or accuracy under transient conditions The data format and the
serial type of interface required were not compatible with industry network communication
standards
The IEEE C37118-2005 Synchrophasor Standard [1] covers adequately most the steady-
state PMU characterization however there are limitations that will need to be addressed in the
new standard It does not specify frequency accuracy requirements Also lack of testing
procedures requirements in the current standard and unavailability of testing equipment are
major issues for PMU testing and calibration [5]
If the input frequency becomes off-nominal the mismatch induces a rotation between the
estimated phasor and the measured phasor causing the TVE to change inside the time window
Possible solutions are suggested in [12 13] including a modification to the standard to add a
TVE limit for the time window or a maximum frequency deviation for the compliance tests
Most importantly to support the increasing demand for high quality PMU applications on
large WAMS the current PMU standard needs to be further developed Future standards should
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1561
P a g e | 8
The Virginia Tech Calibration System copy 2011 Javier Fernandez
show a higher level of detail for dynamic PMU performance requirements testing procedures
and documentation that could guarantee homogeneous performance conformance among PMU
from different manufacturers
The NIST developed the NIST Dynamic Test System for testing PMU performance undertransient conditions and the use of this data for the development of new dynamic performance
requirements for PMUs This PMU dynamic characterization test stand design is described in [10
14 15]
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1461
P a g e | 7
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The TVE is a comparison between a theoretical phasor X and an input phasor
measured by the PMU If a phase shift of ( is added to both X and the phasors would
rotate keeping the ratio between the magnitudes and the TVE constant
This standard also defined the error limits using the TVE concept for the recommended
steady-state compliance tests on the influence quantities shown in Table 32
The NIST developed the NIST PMU Calibration System for testing PMUs for
compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This steady-state
calibration test stand design is described in [9 11]
23 Need for a New Synchrophasor Standard
Some of the IEEE 1344-1995 Synchrophasor Standard [4] limitations were addressed in
the current standard The first standard defined the phasor requirements only at the zero
crossings or 1PPS second mark It did not specify any requirements for dynamic responses such
as measurement response time or accuracy under transient conditions The data format and the
serial type of interface required were not compatible with industry network communication
standards
The IEEE C37118-2005 Synchrophasor Standard [1] covers adequately most the steady-
state PMU characterization however there are limitations that will need to be addressed in the
new standard It does not specify frequency accuracy requirements Also lack of testing
procedures requirements in the current standard and unavailability of testing equipment are
major issues for PMU testing and calibration [5]
If the input frequency becomes off-nominal the mismatch induces a rotation between the
estimated phasor and the measured phasor causing the TVE to change inside the time window
Possible solutions are suggested in [12 13] including a modification to the standard to add a
TVE limit for the time window or a maximum frequency deviation for the compliance tests
Most importantly to support the increasing demand for high quality PMU applications on
large WAMS the current PMU standard needs to be further developed Future standards should
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1561
P a g e | 8
The Virginia Tech Calibration System copy 2011 Javier Fernandez
show a higher level of detail for dynamic PMU performance requirements testing procedures
and documentation that could guarantee homogeneous performance conformance among PMU
from different manufacturers
The NIST developed the NIST Dynamic Test System for testing PMU performance undertransient conditions and the use of this data for the development of new dynamic performance
requirements for PMUs This PMU dynamic characterization test stand design is described in [10
14 15]
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1561
P a g e | 8
The Virginia Tech Calibration System copy 2011 Javier Fernandez
show a higher level of detail for dynamic PMU performance requirements testing procedures
and documentation that could guarantee homogeneous performance conformance among PMU
from different manufacturers
The NIST developed the NIST Dynamic Test System for testing PMU performance undertransient conditions and the use of this data for the development of new dynamic performance
requirements for PMUs This PMU dynamic characterization test stand design is described in [10
14 15]
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1661
P a g e | 9
The Virginia Tech Calibration System copy 2011 Javier Fernandez
3 THE VIRGINIA TECH CALIBRATION S YSTEM DESIGN
31 Requirements Decomposition
The requirements for the Virginia Tech Calibration System were based on the compliance
verification requirements specified in the IEEE C37118-2005 Synchrophasor Standard [1] and
dynamic PMU testing requirements This thesis provides the first and second level breakdown of
the requirement decomposition as shown in Figure 31 Each level was further developed with
the maturation of the design process and system concept
Figure 31 The Virginia Tech Calibration System requirements decomposition
311 System Performance
The IEEE C37118-2005 Synchrophasor Standard [1] specifies an accuracy for standard
test equipment of at least four times compared with the test requirement On the other hand the
PMU Testing Guide [6] increases this accuracy requirement to at least ten times the testing
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1761
P a g e | 10
The Virginia Tech Calibration System copy 2011 Javier Fernandez
specification and also defines an alternate setup where best available test equipment is used for
testing and calibrating the PMUs
A calibration device used to verify performance in accordance with this subclause shall
be traceable to national standards and have a ldquotest accuracy ratiordquo of at least four compared withthese test requirements (for example provide a TVE measurement within 025 where TVE is
1) In cases where there is no national standard available for establishing traceability a detailed
error analysis shall be performed to demonstrate compliance with these requirements[1]
In general the test equipment should be ten times more accurate than the test tolerance ie
the uncertainty of the test equipment should be less than one tenth the test tolerance Under these
conditions the error contribution from the test equipment can generally be ignored in the
evaluation of units under test [6]
There should generally be two setups
Full-featured calibration laboratory ndash used for testing and calibrating both the PMUs and
field test equipment This setup should be equipped with the best possible clock reference
waveform reconstruction (DA) measurement (AD) devices
Standard test equipment - should be ten times more accurate than the test tolerance
Standard test equipment is calibrated using the full-featured calibration laboratory setup
Different options may fall into this category It is important to note that some options may be
suitable for use in labs but some may be used in field Field testing may take place in a
substation control house or switchyard depending on which devices are to be tested
Primary test equipment consists of time reference sources and a multi-phase signal
generator It is suggested that the signal generator be capable of accepting large ldquoplayback filesrdquo
that store point on wave signals that control its output[6]
The NIST designs are full-featured calibration laboratory setups featuring extremely low
uncertainty signal generation data acquisition and signal processing equipment The hardware
modules used in the NIST designs are listed in Table 31
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1861
P a g e | 11
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Table 31 Hardware modules used in the NIST designs983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139830856608 983112983145983143983144 983120983154983141983139983145983155983145983151983150 C983151983157983150983156983141983154983124983145983149983141983154 983159983145983156983144 D983145983143983145983156983137983148 983113983119
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 (3) 983122983151983156983141983147 8100 983155983145983143983150983137983148 983139983137983148983145983138983154983137983156983151983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 983118983113 9831209831289831139830856733 983085 8 983139983144 983137983150983137983148983151983143 983151983157983156983152983157983156 16983085983138983145983156 1 983117983123983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139830856123 983085 8 983139983144 983137983150983137983148983151983143 983145983150983152983157983156 16983085983138983145983156 500 983147983123983155983139983144
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139830858196 20G983144983162 983120983141983150983156983145983157983149 983117 983120983128983113 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 983128983120
These modules are installed in NI PXI-1042 chassis featuring a PXI backplane capable of132Mbs data straming
The NIST PMU Calibration System is calibrated both on time accuracy and on waveform
accuracy It has been calibrated to have less than 0015 maximum magnitude uncertainty and
less than 0009 degree maximum angle uncertainty (less than 04 microsecond time uncertainty)
which means the test system has an uncertainty of less than 0015 TVE[3]
In our design we will be using the NIST software designs with new hardware The
minimum accuracy specification requirements for the new hardware equipment must be the same
as the NIST designs to guarantee at least the same performance
3111 Time Source
The current best available technology for obtaining and referencing UTC time is the
Global Positioning System (GPS) Originally developed for military applications the GPS
system is made up of a network of 24 satellites maintained by the US Department of Defense
referencing atomic clocks These clocks are extremely accurate time sources Factors that may
degrade GPS signal may include atmospheric disturbances such as ionosphere and troposphere
delays number of satellites visible orbital or ephemorsis errors and receiver clock errors[16]
Fluctuations in the GPS time signal may cause short term uncertainty of the GPS time
reference The use of a local receiver clock helps averaging fluctuations over time reducing the
errors in the time signals Since these built-in clocks are not as accurate as atomic clocks the
time signals may drift away from UTC time resulting in considerable offsets errors for our
application Two factors to consider when assessing suitable GPS receivers are the reception
quality of the GPS signal and the stability of the local built-in oscillator
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 1961
P a g e | 12
The Virginia Tech Calibration System copy 2011 Javier Fernandez
A time error of 1 micros corresponds to a phase error of 0022deg for a 60 Hz system and 0018deg
for a 50 Hz system A phase error of 001 radian or 057deg will by itself cause 1 TVE This
corresponds to a maximum time error of plusmn 26 micros for a 60 Hz system and plusmn 31 micros for a 50 Hz
system[1]
3112 Data Acquisition
Phasor accuracy is limited by the data sampling as follows For a minimum error
requirement and a full-scale rating the AD converter needs the following
(31)
The factor radic2 scales the formula from RMS to bipolar peak values which is how AD
converters must be specified[4] Since the calibration system must have an accuracy of ten times
the 1 PMU requirement and the NIST designs use a full-scale of 3X-4X then
(32)
3113 Signal Processing
The NIST designs collect DUT phasor data computes the input test signal phasor and
compares them simultaneously The signal processing power is high but not sufficient to make
the system real-time The DUT data and input signals are buffered and used as needed for
required computations
The NIST designs are modular minimizing custom design for the sub-systems
minimizing costs Also allows for modular upgrades to meet new potential performance
requirements with minimum development time This involves developing module interfaces and
a clear division of software into functional tasks
The signal processing tasks are performed using NI Labview 85 software running on a
NI PXI-8196 embedded controller module using Windows XP operating system This design is
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2061
P a g e | 13
The Virginia Tech Calibration System copy 2011 Javier Fernandez
capable of handling phasor computations for reporting rates of up to 30 frames per second but
system limitations may be found at higher rates
Future synchrophasor standards may require higher PMU reporting rates for which the
NIST signal processing hardware may need to be upgraded to satisfy with the new processingrequirements or the software design modified to allow phasor computation and comparison
operations done entirely off-line
Given the large number of computations required to carry on the dynamic performance
tests a higher performance processor may be required for keeping the testing time relatively
short
312 Parameter TestingThe PMU testing is divided into steady-state and dynamic tests The IEEE C37118-2005
Synchrophasor Standard [1] defines each steady-state conformance test requirements and limits
The PMU Testing Guide [6] covers in more detail the steady-state tests and defines each
dynamic performance test and requirements
PMUrsquos usually must undertake factory acceptance tests commissioning tests and
maintenance tests Furthermore the PMU must also satisfy requirements tailored to its
application such as interoperability with other PMU system components common performancewith other units in the monitoring network high time synchronization and tagging accuracy The
steady-state and dynamic test requirements are defined for test signal injected at the PMUrsquos input
terminals[6]
3121 Steady-State Testing
The steady-state condition is defined per the standard as where the magnitude frequency
phase and all other influence quantities of the test signal are constant during the period of the
testing [1] The steady-state tests are performed to verify that the PMU accuracy is within theallowed limits when working under defined steady-state operating conditions The compliance
requirements shown in Table 32 specify the TVE level for signal frequency phasor magnitude
measurement phasor angle measurement harmonic distortion and out-of-band interference
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2161
P a g e | 14
The Virginia Tech Calibration System copy 2011 Javier Fernandez
All compliance tests are to be performed under steady-state conditions with reference
conditions and influence quantities as defined in Table 32 Effects of the influence quantities
shall be considered cumulative and the TVE shall not exceed the error listed for the given
compliance level under any combination of influence quantities shown in Table 32 To evaluate
compliance with this requirement the effects of the influence quantities may be separately
evaluated[6]
The steady-state tests proposed in the PSTT PMU Testing Guide [2] are divided into two
types conformance and functional performance tests The steady-state conformance tests are
required for compliance with the current synchrophasor standard magnitude accuracy test phase
accuracy test frequency accuracy test off-nominal frequency response test harmonic frequency
response test and out-of-band interference test The steady-state functional performance tests are
as follows rate of change of frequency accuracy test unbalanced magnitude response test
unbalanced phase response test and data reporting test
Table 32 Influence quantities and allowable error limits for compliance levels 0-1 [IEEEStandard for Synchrophasors for Power Systems 2006] Illustrated under ldquoFair Userdquo copyright
guidelines
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2261
P a g e | 15
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The NIST designs provides a set of automated tests for all PMU influence quantities
shown in Table 32 in steady-state as required for DUT compliance with the IEEE C37118-
2005 Synchrophasor Standard [1]
3122 Dynamic Testing
For dynamic tests the input signal varies during the period of the testing according to the
type of test being performed The PMU Testing Guide [6] suggests the following test to cover
PMU characterization under dynamic or transient conditions step change response for amplitude
phase and frequency along with frequency ramp and amplitude modulation
3123 Protocol Testing
This test is required to ensure interoperability among PMU devices across the monitoring
system It includes testing the message application entirely for all message types defined in itsframework for compliance with the IEEE C37118-2005 Synchrophasor Standard [1] This test
must be conducted prior to conformance and performance testing
313 Documentation
According to the IEEE C37118-2005 Synchrophasor Standard [1] documentation must
be provided by any vendor claiming compliance with the standard that shall include a statement
of the compliance level being achieved and demonstrating this performance In addition if the
verification system is based on an error analysis as called for previously this analysis shall be
provided as well[1]
In the NIST designs the test results are generated automatically by the signal processing
software The reports include all data pertaining to the corresponding test being conducted
graphs statistics and test parameters
32 System Definition
The Virginia Tech Calibration System is a steady-state and dynamic PMU calibration test
stand used for compliance verification with the IEEE C37118-2005 Synchrophasor Standard [1]
based on the NIST PMU Calibration System and NIST Dynamic Test System designs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2361
P a g e | 16
The Virginia Tech Calibration System copy 2011 Javier Fernandez
321 System Description and High-level Architectural Depiction
The overall system involves providing the DUT interface the calibration test of the PMU
and the delivery of statistical data to determine PMU compliance with the synchrophasor
standard The major components and identified processes are listed in Table 33
Table 33 Major processing component descriptions in the Virginia Tech Calibration System983117983137983146983151983154 983120983154983151983139983141983155983155 983151983154 983107983151983149983152983151983150983141983150983156 983106983137983155983145983139 983108983141983155983139983154983145983152983156983145983151983150
983124983145983149983141 983123983151983157983154983139983141 983120983154983151983158983145983140983141 983156983145983149983141 983140983137983156983137 983137983150983140 983155983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983155983145983143983150983137983148983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150 983120983154983151983158983145983140983141 983120983117983125 3983085983152983144983137983155983141 983156983141983155983156 983159983137983158983141983142983151983154983149
983123983145983143983150983137983148 A983156983156983141983150983157983137983156983145983151983150 983113983150983152983157983156 983155983145983143983150983137983148 983139983151983150983140983145983156983145983151983150983145983150983143 983152983154983145983151983154 983156983151 983155983137983149983152983148983145983150983143 983152983154983151983139983141983155983155
983123983137983149983152983148983145983150983143 983137983150983140 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983120983144983137983155983151983154 983139983151983149983152983157983156983137983156983145983151983150 983137983150983140 D983125983124 983140983137983156983137 983139983151983149983152983137983154983145983155983151983150
D983125983124 983113983150983156983141983154983142983137983139983141 983120983154983151983158983145983140983141 983137983139983139983141983155983155 983156983151 983120983117983125 983157983150983140983141983154 983156983141983155983156
The high level architectural depiction and representation of the major components are
seen in Figure 32 The high level depiction shows the overall concept for the Virginia Tech
Calibration System and the major processes that are addressed in the design process
Figure 23 The Virginia Tech Calibration System high level architectural depiction
The NIST used the same approach for both the steady-state and dynamic PMU
calibration designs A National Instruments (NI) platform was used to develop a PMU capable oftaking phasor measurements with minimum uncertainty the NI PMU The test signals were
generated and fed to both the NI PMU and the PMU under test Then the measured phasor data
was compared in order to determine whether the device under test (DUT) passed the test
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2461
P a g e | 17
The Virginia Tech Calibration System copy 2011 Javier Fernandez
33 Steady-state Design
The National Instrument platform was selected for the PMU Calibration System design
The tests were developed using a graphical programming environment the NI Labview 85
development package The hardware modules described in Table 34 were installed in a rack
featuring a 10MHz timing and synchronization backplane with external clock input the NI PXIe-
1062Q chassis
Table 34 Hardware used in the Virginia Tech Calibration System steady-state designC983148983151983139983147 983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150983123983156983141983137983140983161983085983155983156983137983156983141 983119983149983145983139983154983151983150 C983117C 156 E983120 3983085983120983144983137983155983141 C983137983148983145983138983154983137983156983151983154
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in NI PXIe-1062Q chassis featuring a PXI express backplanecapable of 1GBs data streaming
Labview is divided into functional tasks called virtual instruments (VIs) Each VI has a
block diagram a front panel and a connection panel The front panel consists of controls and
indicators that allow the user to enter data and to get data from a running VI These controls can
also serve as interfaces to other VIs when dropped as a node onto the block diagram This
functionality allows the testing of VIs before being integrated as a subroutine into a larger
program
Labview is a dataflow programming language The execution order follows the structure
of a graphical block diagram where the developer connects VIs by drawing wires The VIs get
executed as soon as input data becomes available allowing parallel execution[17]
The signal processing software interfaces with all hardware modules through the different
interfaces shown in Table 35
Table 35 Software interface VIs in the Virginia Tech Calibration SystemD983125983124 983113983150983156983141983154983142983137983139983141 983122983157983150983135D983125983124983135983124C983120 983126983113 991251 983124C983120 983120983154983151983156983151983139983151983148
983124983145983149983141 983123983151983157983154983139983141 G983120983123983135983124983145983149983141983155983156983137983149983152983135983113983150983145983156 983126983113 991251 983118983113983085983123983161983150983139 D983154983145983158983141983154983155
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 3983120983135983126A983135C9831519831509831429831459831436213 983126983113 991251 983118983113983085DA983121983149983160 D983154983145983158983141983154983155
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2561
P a g e | 18
The Virginia Tech Calibration System copy 2011 Javier Fernandez
331 Time Source
The time source is used as a reference for time stamping the test signal and for triggering
the sampling module
The NIST designs included an interface for the GPS module using the NI DAQmxfunction library the GPS_Timestamp_Initvi This VI configured the clock-synchronization of
the NI PXI-6608 timing module with an external GPS receiver unit via IRIG-B and outputted a
timestamp upon the 1-PPS rising edge GPS signal This event triggered a timing clock
maintained by the data acquisition module built-in sampling clock used for time stamping each
PMU phasor frame at the rate selected for the test
The Virginia Tech Calibration System design includes a GPS-based time source the NI
PXI-6682H timing module The new interface was based on the GPS_Timestamp_Initvi and
modified using a library of functions for controlling NI timing modules the NI-Sync driver
software This VI was simplified to directly request the GPS module through the backplane for
a timestamp upon the 1-PPS rising edge GPS signal
The time source module selected for the Virginia Tech design has slightly less accuracy
than the NIST designs as shown in Table 36 corresponding to an additional phase error in the
Virginia Tech Calibration System of 0000748deg for a 60 Hz system and 0000612deg for a 50 Hz
system The Symetricom xLI GPS accuracy specifications were obtained from [18] Detailed
specifications of the NI PXI-6682H GPS module are shown in Appendix A
Table 36 Time source module accuracy comparison with the NIST designs983123983129983117E983124983122983113C983119983117 983160983116983113 G983120983123 983118983113 9831209831289831139830856682983112
1983120983120983123 98321730983150983155 983122983117983123 100983150983155 983152983141983137983147 98321747983150983155 983122983117983123 100983150983155 983152983141983137983147 983085
332 Signal Generation
The NIST designs included three Rotek 8100 signal calibrator units for steady-state
signal generation and an IRIG-B interface VI the Rotek Calibrator library
In the Virginia Tech Calibration System the steady-state signals were generated using a
high precision three-phase calibrator the Omicron CMC 156 EP Its interface featured the step
and ramp signal generation for all the signal influence quantities required on the steady-state
testing the Omicron QuickCMC interface
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2661
P a g e | 19
The Virginia Tech Calibration System copy 2011 Javier Fernandez
The signal generation hardware selected for the Virginia Tech Calibration System has the
same accuracy under typical conditions as the NIST designs as shown in Table 37 Additional
detailed specifications for the Omicron CMC 156 are shown in Appendix B
Table 37 Signal generation module accuracy comparison with the NIST designs983122983151983156983141983147 8100 983119983149983145983139983154983151983150 C983117C 156
983126983151983148983156983137983143983141 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
C983157983154983154983141983150983156 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 001 983151983142 983126983151983148983156983137983143983141 983123983141983156983156983145983150983143 =
333 Data Acquisition
The NIST designs included the NI PXI-6123 data acquisition module featuring eight
analog input channels The voltage and current were measured for each phase using only six
input channels from the card The current feedbacks from the current transducers were a voltage
proportional to the current levels Its software interface the 3P_VA_Config_6123_d VI used the NI DAQmx function library to set up the analog input card measuring range sampling rate and
trigger for selected channels
The Virginia Tech Calibration System included the NI PXIe-6356 data acquisition
module featuring eight analog input channels Its interface uses the 3P_VA_Config_6123_d VI
with modified input parameters to match the new hardware
The signal generation hardware selected for the Virginia Tech Calibration System asshown in Table 38 is capable of a higher sampling rate which improves the accuracy of the
phasor estimation Additional detailed specifications for the NI PXIe-6356 data acquisition
module are shown in Appendix C
Table 38 Data acquisition module accuracy comparison with the NIST designs983118983113 9831209831289831139830856123 983118983113 9831209831289831139831419830856356
ADC 983154983141983155983151983148983157983156983145983151983150 16 983138983145983156 16 983138983145983156 =
983123983137983149983152983148983145983150983143 983154983137983156983141 500 983147983123983155 125 983117983123983155 +
334 Signal Processing
The NIST designs included a NI PXI-8196 20Ghz Pentium M PXI Embedded Controller
and a set of VIs to perform the PMU function and phasor estimation and to compare it with the
DUT phasor data the Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2761
P a g e | 20
The Virginia Tech Calibration System copy 2011 Javier Fernandez
In the Virginia Tech Calibration System the signal processing tasks were performed by a
high-performance processor-based embedded controller the NI PXIe-8108 controller module
The Run_NI2New_C and the RT_NI_DUT_Compare_eSAVE VIs were used for the signal
processing tasks
The NI PXIe-8108 includes a dual-core processor capable of executing two computing
tasks simultaneously This is a major advantage over single-core embedded controllers such as
the NI PXI-8196 when executing Labview multi-threaded applications like the Run_NI2New_C
and the RT_NI_DUT_Compare_eSAVE VIs
National Instruments claims a performance improvement of up to one hundred percent on
multi-threaded applications between the NI PXI-8196 and the NI PXI-8105 one of the first dual-
core embedded controller systems [20] Using SYSmark benchmarking software NI PXIe-8108
controllers demonstrate an overall performance improvement of one hundred and nine percent
over the PXI-8105 controllers [21 22] Therefore the VT Calibration system signal processor
performance is over two hundred per cent higher than the one used in the NIST designs as
shown in Table 39
Table 39 Signal processing module accuracy comparison with the NIST designs983118983113 9831209831289831139830858196 983118983113 9831209831289831139831419830858108
983120983154983151983139983141983155983155983151983154983124983161983152983141
983113983150983156983141983148 983120983141983150983156983145983157983149 983117 760 983113983150983156983141983148 C983151983154983141 2 D983157983151 9831249400 +
335 Clock Synchronization
The NIST designs included the Symmetricom XLi GPS 10MHz frequency output as the
clock synchronization source for the data acquisition and signal generation modules
In the Virginia Tech Calibration System an DUT B 1084B featuring a 10MHz frequency
output is used as the clock synchronization source No software interface was required for this
module since it connected directly to the NI chassis clock input via a coaxial cable
The clock synchronization source hardware selected for the Virginia Tech Calibration
System is slightly more accurate than the NIST designs as shown in Table 310 The
Symetricom xLI GPS accuracy specifications were obtained from [18] However the NIST
designs use the same GPS module as a time and clock synchronization source while the Virginia
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2861
P a g e | 21
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Tech design uses two GPS modules The Arbiter 1084B has a UTC synchronization accuracy of
forty nanoseconds RMS and hundred nanoseconds peak as specified in [23] The accuracy of
both GPS modules combined is eighty seven nanoseconds corresponding to an additional phase
error in the Virginia Tech Calibration System of 0001254deg for a 60 Hz system and 0001026deg
for a 50 Hz system
Table 310 Synchronization source accuracy comparison with the NIST designs
983123983129983117983117E983124983122983113C983119983117 983128983116983145 G983120983123 A983154983138983145983156983141983154 1084B
983125983150983148983151983139983147983141983140
983119983155983139983145983148983148983137983156983151983154
983155983156983137983138983145983148983145983156983161
983126C983124C983128983119 5983160109830857
DC983128983119 1983160109830857
+
A983148983148983137983150
D983141983158983145983137983156983145983151983150
983155983156983137983138983145983148983145983156983161
1983160109830859 983152983141983154 983155983141983139 59831601098308510 983152983141983154 983155983141983139 +
336 Signal Attenuation
The NIST designs included a Jamb CT two hundred to one NIST built two-stage current
transducers and twenty to one or two hundred to one resistive attenuators with Vishay low
temperature coefficient resistors with capacitor tuning voltage attenuators
The Virginia Tech Calibration System used a twenty to one voltage divider for voltage
attenuation and high precision current shunt resistors for current attenuation The phase error
introduced by the different signal attenuation implementations was properly compensated bysetting a phase correction factor in the NI PMU
337 DUT interface
The NIST and the Virginia Tech Calibration System designs included a software
interface using TCP and UDP protocols to exchange data with the DUT the Run_DUT_TCP and
the Run_DUT_UDP VIs
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 2961
P a g e | 22
The Virginia Tech Calibration System copy 2011 Javier Fernandez
34 Dynamic Testing Design
The dynamic testing design is similar to the steady-state design with the exception of the
signal generation component as shown in Table 311 The Omicron CMC 156 EP is not capable
of producing the test signals required for the dynamic tests
Table 311 Hardware used in the Virginia Tech Calibration System dynamic design983123983161983150983139983144983154983151983150983145983162983137983156983145983151983150 983123983151983157983154983139983141 D983125983124 B 1084B G983120983123 983123983137983156983141983148983148983145983156983141 C983148983151983139983147
983124983145983149983141 983123983151983157983154983139983141 983118983113 9831209831289831139831419830856682983112 G983120983123 C983148983151983139983147 983137983150983140 983124983145983149983141983154
983123983145983143983150983137983148 G983141983150983141983154983137983156983145983151983150D983161983150983137983149983145983139983118983113 9831209831289831139830856733 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983151983157983156983152983157983156
(3) C983154983151983159983150 983120983123983085400 983120983151983159983141983154 A983149983152983148983145983142983145983141983154983155
D983137983156983137 A983139983153983157983145983155983145983156983145983151983150 983118983113 9831209831289831139831419830856356 983085 8 983139983144983137983150983150983141983148 983137983150983137983148983151983143 983145983150983152983157983156
983123983145983143983150983137983148 983120983154983151983139983141983155983155983145983150983143 983118983113 9831209831289831139831419830858108 253G983144983162 D983157983137983148983085C983151983154983141 983120983128983113 983141983160983152983154983141983155983155 E983149983138983141983140983140983141983140 C983151983150983156983154983151983148983148983141983154 983127983145983150 7
These modules are installed in a NI PXIe-1062Q chassis featuring a PXI express backplane
capable of 1GBs data streaming341 Signal Generation
The NIST Dynamic Test System design included the NI PXI-6733 analog output module
and a set of Rotek 8100 amplifiers for dynamic test signal generation
The Virginia Tech Calibrator System uses the NI PXI-6733 analog output module and
three Crown PS-400 power amplifiers The test signals are created in software by the different
VIs running the dynamic tests Additional detailed specifications for the NI PXI-6733 analog
module are shown in Appendix D
The amplifier module used in the Virginia Tech Calibration System is less accurate than
the NIST Dynamic Test System design as shown in Table 312 however this should not introduce
additional error in the tests since the test signals are fed to both the NI PMU and the DUT The
Rotek 8100 accuracy specifications were obtained from [24] The Crown PS-400 accuracy
specifications were obtained from [25]
Table 312 Dynamic signal generation accuracy comparison with the NIST Dynamic TestSystem design983122983151983156983141983147 8100 C983154983151983159983150 983120983123983085400
983120983151983159983141983154
A983139983139983157983154983137983139983161001 01 983085
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3061
P a g e | 23
The Virginia Tech Calibration System copy 2011 Javier Fernandez
35 Calibration
The Virginia Tech Calibration System is compensated for phase errors introduced in the
NI PMU measurements by various delay sources such as the wiring between the modules
current transducers phase shifts etc
Figure 45 Phase calibration of reference PMU with the 1PPS clock signal [PMU System
Testing and Calibration Guide 2007] Illustrated under ldquoFair Userdquo copyright guidelines
Calibration involves reading the phase errors in the NI PMU measurement from input
signals with known phase angles and then adding the phase compensations in the software The
signal source is clock synchronized to UTC time and phase shifted so the positive zero crossing
of Phase A is aligned with the 1PPS the NI PMU should read -90 degrees if properly calibrated
The signal source is readjusted to align the 1PPS with the negative zero crossing of Phase A the
NI PMU should read +90 degrees A high precision oscilloscope is set to trigger on the 1PPS
rising edge as shown in Figure 33 The signal source must generate a high frequency outputduring calibration to be able align the test signal with the 1PPS[6]
Once the phase delays are determined they can be manually inputted into the front panel
of the NI PMU the Run_NI2New_C VI or through the calibration program the TimeDelayTest
VI
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3161
P a g e | 24
The Virginia Tech Calibration System copy 2011 Javier Fernandez
4 STEADY-STATE TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess steady-state
performance of a PMU DUT A
41 Accuracy and Time Alignment
This section shows the tests performed to assess accuracy and time alignment of PMUs
The accuracy and time alignment tests include magnitude phase angle and frequency tests
The RT_NI_DUT_Compare_eSave VI is executed simultaneously with the
corresponding VIs used to run the different accuracy tests It starts the NI PMU via the
Run_NI2New_C VI and connects to the DUT via the Run_DUT_TCP VI to gather the data and
perform the phasor comparisons and to send the errors to the DisplayErrorsLVM4 VI This
program displays the errors and saves the data to NI DIAdem files The NI DIAdem is a software
tool used for data archiving and analysis
411 Magnitude Accuracy
The MagTestRunNI VI is used to run the voltage and current magnitude accuracy tests
For the voltage magnitude accuracy test this program executes the
RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of 10 to 120 in
steps of 5 of nominal voltage with an adjustable delay in between the steps Each magnitude
step is maintained for one minute until the test is completed The phasor data comparison results
between the NI PMU and the DUT are analyzed and the minimum maximum and mean TVE
values are sent to the DisplayErrorsLVM4 VI The current level is kept constant during the test
In the current magnitude accuracy test the current levels are stepped and the voltage
level is kept constant
The steady-state generator is updated in between the magnitude steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 42 shows the MagTestRunNI VI Block Diagram The Error_Stats VIs compute
the TVE statistics of the phasor data comparison between the PMUs later shown in Figures 43
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3261
P a g e | 25
The Virginia Tech Calibration System copy 2011 Javier Fernandez
44 and 45 The Error_Stats_Vector computes other frequency statistical errors The
Update_Mag VI in the NIST PMU Calibration System design was an IRIG-B interface with the
signal generator module It updated the test signal magnitude levels automatically during the test
using Rotek drivers This function is not available in the Virginia Tech Calibrator System
because Labview drivers for the Omicron CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the MagTestRunNI VI Front
Panel lower left corner shown in Figure 41
Figure 43 shows the magnitude accuracy test results performed on DUT A
Figure 41 MagTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3361
P a g e | 26
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 42 MagTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3461
P a g e | 27
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 43 Voltage magnitude accuracy test results
412 Phase Accuracy
The PhaseTestRunNI VI is used to run the phase accuracy tests This program executes
the RT_NI_DUT_Compare_eSave VI with test signal magnitude parameters of -180˚ to 180˚ in
steps of 10˚ with an adjustable delay in between the steps Each phase step is maintained for one
minute until the test is completed The phasor data comparison results between the NI PMU and
the DUT are analyzed and the minimum maximum and mean TVE values are sent to the
DisplayErrorsLVM4 VI
The steady-state generator is updated in between the phase steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 45 shows the PhaseTestRunNI VI Block Diagram The Update_Phase VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3561
P a g e | 28
The Virginia Tech Calibration System copy 2011 Javier Fernandez
It updated the test signal phase automatically during the test using Rotek drivers This function is
not available in the Virginia Tech Calibrator System because Labview drivers for the Omicron
CMC 156 EP have not been developed yet
The magnitude accuracy test parameters are inputted in the PhaseTestRunNI VI FrontPanel lower left corner shown in Figure 44
Figure 46 shows the phase accuracy test results performed on DUT A
Figure 44 PhaseTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3661
P a g e | 29
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 45 PhaseTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3761
P a g e | 30
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 46 Phase accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3861
P a g e | 31
The Virginia Tech Calibration System copy 2011 Javier Fernandez
413 Frequency Accuracy
The FreqTestRunNI VI is used to run the frequency magnitude accuracy tests This
program executes the RT_NI_DUT_Compare_eSave VI with test signal frequency parameters of
54 to 66Hz in steps of 01Hz with an adjustable delay in between the steps Each frequency step
is maintained for one minute until the test is completed For 50Hz systems the test signal
frequency parameters are 44 to 56 Hz
The steady-state generator is updated in between the frequency steps to generate the
corresponding test signal levels using the Omicron QuickCMC interface
Figure 48 shows the FreqTestRunNI VI Block Diagram The Update_Freq_2 VI in the
NIST PMU Calibration System design was an IRIG-B interface with the signal generator module
It updated the test signal frequency levels automatically during the test using Rotek drivers This
function is not available in the Virginia Tech Calibrator System because Labview drivers for the
Omicron CMC 156 EP have not been developed yet
The frequency accuracy test parameters are inputted in the FreqTestRunNI VI Front
Panel lower left corner shown in Figure 47
Figures 49 shows the frequency test results performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 3961
P a g e | 32
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 47 FreqTestRunNI VI front panel
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4061
P a g e | 33
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 48 FreqTestRunNI VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4161
P a g e | 34
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 49 Frequency accuracy test results
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4261
P a g e | 35
The Virginia Tech Calibration System copy 2011 Javier Fernandez
5 D YNAMIC TESTING
This chapter shows the results of test performed by the Virginia Tech Calibration System
and explain the interaction between the hardware and the software used to assess the dynamic
performance of a PMU DUT A
51 Step Change response
This section shows the tests performed for determining performance of PMUs in response
to step changes The step change response tests include magnitude phase angle and frequency
tests
The Run_Step_Test_on_DUTs_add VI is used to run the step change response tests It
uses the concept of interleaving phasors developed in [15] Each test is executed using the
NI_DUT_Step_add VI The error data is sent to the DisplayampStore VI This program displays
the errors and saves the data to NI DIAdem files
The NI_DUT_Step_add VI Block diagram is shown in Figure 51 The Run_NI_Add VI
generates the test signals and starts the NI PMU The Collect_data VI gathers and aligns the
phasor data according to their time stamps The Analyze_Data VI performs the phasor
comparisons
The Run_DUT_TCP_add VI is executed simultaneously with the
Run_Step_Test_on_DUTs_add VI to start the DUT
The test parameters are inputted in the Run_Step_Test_on_DUTs_add VI Front Panel
shown in Figure 52
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4361
P a g e | 36
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 51 NI_DUT_Step_add VI block diagram
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4461
P a g e | 37
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 52 Run_Step_Test_on_DUTs_add VI front panel
511 Dynamic Magnitude Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic magnitude step changeresponse test for voltage and current For the voltage this program executes the
NI_DUT_Step_add VI with an amplitude step change of 20 of nominal voltage The current
level is kept constant The test signal is shown in Figure 53
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4561
P a g e | 38
The Virginia Tech Calibration System copy 2011 Javier Fernandez
For the current magnitude step change test the current is stepped and voltage is kept
constant The Crown PS-400 power amplifier was not capable of producing the current signals It
often became unstable and tripped when stepping the current
Figure 54 shows the magnitude step change response test results performed on DUT A
Figure 53 Magnitude step change test signal
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4661
P a g e | 39
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 54 Magnitude step change test results
512 Dynamic Phase Response
The Run_Step_Test_on_DUTs_add VI is used to run the dynamic phase step change
response test This program executes the NI_DUT_Step_add VI with phase step changes of plusmn15˚
and plusmn45˚ The test signals for the plusmn45˚ phase step change test are shown in Figures 55 and 56
Figures 57 and 58 show the plusmn45˚phase step change response test results performed on
DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4761
P a g e | 40
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 55 Phase step change test signal (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4861
P a g e | 41
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 56 Phases step change test signal (+45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 4961
P a g e | 42
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 57 Phase step change test results (-45˚)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5061
P a g e | 43
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 58 Phase step change test results (+45˚)
513 Dynamic Frequency Response
The Run_Step_Test_on_DUTs_add VI is used to run the frequency phase step change
response test This program executes the NI_DUT_Step_add VI with frequency step changes of
plusmn1Hz plusmn2Hz and plusmn3Hz The test signals for the plusmn2Hz frequency step change test are shown in
Figures 59 and 510
Figures 511 and 512 show the plusmn2Hz frequency step change response test results
performed on DUT A
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5161
P a g e | 44
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 59 Frequency step change test signal (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5261
P a g e | 45
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 510 Frequency step change test signal (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5361
P a g e | 46
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 511 Frequency step change test results (-2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5461
P a g e | 47
The Virginia Tech Calibration System copy 2011 Javier Fernandez
Figure 512 Frequency step change test results (+2Hz)
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5561
P a g e | 48
The Virginia Tech Calibration System copy 2011 Javier Fernandez
6 CONCLUSIONS AND RECOMMENDATIONS
A test stand for steady-state and dynamic characterization of PMUs based on the NIST
PMU Calibration System and the NIST Dynamic Test System was developed at Virginia Tech
the Virginia Tech Calibration System
The hardware requirements were specified in order to meet and improve the performance
of the NIST designs within the project budget The NI platform was selected for the data
acquisition dynamic signal generation and data processing functions in order to implement the
NIST design software
The hardware modules were installed and tested using NI tools prior to integration with
the NIST software The different software module interfaces were modified to adapt the newhardware drivers The software modifications performed in the Virginia Tech Calibration System
do not affect the overall performance of the system
A GPS based synchronization scheme was implemented across the hardware modules to
guarantee minimum phase errors in the NI PMU measurements The time and clock
synchronization implementation have added an additional phase error of 0001254deg for a 60 Hz
system and 0001026deg for a 50 Hz system
The amplifiers used in the dynamic design were not capable of producing the test signals
required to conduct the current varying tests This limitation is believed to be caused by
deteriorations due to aging as the Crown PS-400 power amplifiers used in the dynamic design
were manufactured in the late eightyrsquos A set of high performance amplifiers may be required to
perform the complete set of dynamic performance tests
After reviewing the hardware differences and software modifications the Virginia Tech
Calibration System performance compares very close to the NIST design The steady-state anddynamic tests shown in chapters 4 and 5 of this thesis were supervised by the NIST showing
successful functioning of the Virginia Tech Calibration System
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5661
P a g e | 49
The Virginia Tech Calibration System copy 2011 Javier Fernandez
REFERENCES
1 IEEE Standard for Synchrophasors for Power Systems IEEE Standard C37118-2005
March 20062 Moraes R et al Deploying a large-scale PMU system for the Brazilian interconnected
power system Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2008) p 143-149
3 Hu Y D Novosel and R Quanta Technol NC Progresses in PMU testing and
calibration Electric Utility Deregulation and Restructuring and Power Technologies2008 DRPT 2008 (6-9 April 2009) p 150-155
4 IEEE Standard for Synchrophasors for Power Systems IEEE Standard 1344-
1995(R2001) March 20015 Huang Z et al Performance Evaluation of Phasor Measurement Systems Power
Engineering Society General Meeting 2008 IEEE6 PMU System Testing and Calibration Guide Technical Report for the North American
Synchrophasor Initiative Performance and Standard Task Team team leader G
Stenbakken7 Synchrophasor Measurement Accuracy Characterization Technical Report for the NorthAmerican Synchrophasor Initiative Performance and Standard Task Team team leader GStenbakken
8 Bill Mittelstadt J Kehler and S Kothepalli WECC Plan for Dynamic Performance and
Disturbance Monitoring WECC Disturbance Monitoring Work Group 20009 Stenbakken G and T Nelson Static Calibration and Dynamic Characterization of
PMUs at NIST Power amp Energy Society General Meeting 2007 IEEE10 Stenbakken GN and M Zhou Dynamic Phasor Measurement Unit Test System IEEE
Power Engineering Society General Meeting11 Stenbakken G and T Nelson NIST support of phasor measurements to increase
reliability of the North American electric power grid Power amp Energy Society GeneralMeeting 2006 IEEE12 Donolo M and VA Centeno Accuracy Limits for Synchrophasor Measurements and
the IEEE Standard IEEE Transactions on Power Delivery (Jan 2008)13 Phadke AG and B Kasztenny Synchronized Phasor and Frequency Measurement
Under Transient Conditions IEEE Transactions on Power Delivery 24(1)14 Stenbakken G et al Reference Values for Synamic Calibration of PMUs Hawaii
International Conference of System Sciences Proceedings of the 41st Annual (7-10 Jan2008) p 171-171
15 J Ren M Kezunovic and G Stenbakken Characterizing dynamic behavior of PMUs
using step signals European Transactions on Electric Power 2011
16 Wang L et al An Evaluation of Network Time Protocol for Clock Synchronization inWide Area Measurements Power amp Energy Society General Meeting 2008 IEEE
17 National Instruments Labview User Manual April 2003
18 Symmetricom XLi Time and Frequency System Symmetricom XLi datasheet Oct 200519 National Instruments NI PXI-81958196 User Manual NI PXI-8105 datasheet March
2005
20 National Instruments 20 GHz Dual-Core Embedded Controller for PXI NI PXI-8105
datasheet March 2006
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5761
P a g e | 50
The Virginia Tech Calibration System copy 2011 Javier Fernandez
21 National Instruments 216 GHz Dual-Core Embedded Controller for PXI and PXI
Express NI PXI-8106 and NI PXIe-8106 datasheet Jan 200722 National Instruments 253 GHz Dual-Core Embedded Controller for PXI Express NI
PXIe-8108 datasheet Sep 2008
23 Arbiter Systems Model 1084ABC GPS Satellite Clock Arbiter 1084B datasheet Dec
201024 Rotek The Rotek Model 8100 Rotek 8100 datasheet Jan 2004
25 Omicron CMS 156 3 Phase Voltage and Current Amplifier CMS 156 technical data
July 201026 National Instruments NI PXI-6682 and PXI-6682H Timing and Synchronization Modules
for PXI NI PXI-6682 Series User Manual March 2009
27 Omicron CMC 156 EP 3 Phase Voltage + 3 Phase Current Test Set CMC 156 EP
technical data Sep 201028 National Instruments NI 63566358 Specifications NI PXIe-63566358 technical data
Aug 201029 National Instruments NI 67316733 Specifications NI PXI-67316733 technical data
June 2007
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5861
P a g e | 51
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX A NI PXI-6682 TIMING MODULE TECHNICAL
SPECIFICATIONS
Table A1 lists the synchronization accuracy that the PXI-6682H offers while operating
in various modes[26]
Table A1 NI PXI-6682H synchronization accuracy
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 5961
P a g e | 52
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX B OMICRON CMC 156 EP TECHNICAL
SPECIFICATIONS
Figure B1 shows the Omicron CMC 156 technical specifications for voltage and current
generation[27]
Figure B1 Omicron CMC 156 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6061
P a g e | 53
The Virginia Tech Calibration System copy 2011 Javier Fernandez
APPENDIX C NI PXIE-6356 DATA ACQUISITION MODULE
TECHNICAL SPECIFICATIONS
Table C1 shows the NI PXIe-6356 for analog input obtained from [28]
Table C1 NI PXIe-6356 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications
7212019 Fernandez JO T 2011
httpslidepdfcomreaderfullfernandez-jo-t-2011 6161
P a g e | 54
APPENDIX D NI PXI-6733 ANALOG OUTPUT MODULE
TECHNICAL SPECIFICATIONS
Table D1 shows the NI PXI-6733 for analog output obtained from [29]
Table D1 NI PXI-6733 technical specifications