wide area measurement

8/11/2019 Wide Area Measurement

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Smart Grid, Smart City Project

Monitoring and Measurement Report

Report III

Grid Applications Stream: Wide Area Measurement

01 January 2012 30 June 2012


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Smart Grid, Smart City Monitoring and Measurement Report III Wide Area Measurement 2

IMPORTANT NOTE:

In a number of attachments, Ausgrid has removed certain material that we do not consider

appropriate to release, such as personal information and commercially sensitive financial information.

Ausgrid believes the removal of this information does not detract from the general value of the

information or findings in the attachments.

This document has been approved for publication by Ausgrid and the consortium partners who

contributed to it. The document has been prepared with all reasonable care and responsibility.

Ausgrid believes these findings to be technically and factually accurate when applied to Ausgrids

network as at the date of those findings.

However it should not be considered a recommendation and naturally, it would be prudent for anyone

who wishes to rely on, or use the information in this report to independently verify its accuracy,

completeness and suitability for use for their own purpose.

Consequently, Ausgrid makes no representation or warranty as to the accuracy, currency, reliability,

completeness or suitability, of the information in this report. You acknowledge that Ausgrid (and itsofficers, employees, agents and consultants) to the full extent permitted by law, excludes all liability:

(a) (including liability to any person by reason of negligence or negligent misstatement) for any

statement, opinion, information or matter (expressed or implied) contained in, and for any omissions

from, this document; and (b) arising out of your use of or reliance on this document and any

information contained in it.

Ausgrid owns copyright in (or otherwise has the rights necessary to publish) this document. You may

only reproduce this document with the permission of Ausgrid.


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Contents

1 Wide Area Measurement ................................................................................... 5

1.1

Introduction ............................................................................................................................... 5

1.2

Trial Design and Architecture .................................................................................................. 6

1.2.1 Trial Location ....................................................................................................................... 6

1.2.2

WAM Trial Components ...................................................................................................... 7

1.3 Activities .................................................................................................................................... 9

1.4

Analysis and results ............................................................................................................... 10

1.4.1 Data Priorities .................................................................................................................... 10

1.4.2

Data gathered.................................................................................................................... 10

1.4.3 Analysis ............................................................................................................................. 14

1.5

Lessons Learnt ........................................................................................................................ 14

1.6

Case studies ............................................................................................................................ 15


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Attachment List

AREA TITLE CATEGORY TYPE

GA MMR3_GA_WAM_Beresfield and Singleton phase B.xlsx Raw Data Spreadsheet


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1 Wide Area Measurement

1.1 Introduction

Wide Area Measurement seeks to monitor network stability of the HV network. Stability includes a

number of grid management aspects including: state determination and grid imbalance (voltage

stability, phase imbalance); disturbance recording; network safety; and generation control. Improved

planning will also result from the data gathered from WAM. The trial will evaluate the use of phasor

measurement unit (PMU) technology in improving system stability, avoiding cascading load shedding

during system overload (supported by wide area protection schemes), providing data to enable event

analysis (subsequent to a wide scale unplanned outage), and supporting "black start" recovery when

returning from a wide scale outage. The measurement takes place at transmission and sub-

transmission substations, therefore involving TransGrid as well as Ausgrid.

Measurement is achieved through the installation of 11 PMUs along high voltage corridors in the

Transmission network (TransGrid 5 units) and Distribution network (Ausgrid 6 units). Other

monitoring (existing data collected through SCADA) is combined to give an overall picture of grid

stability. Monitoring and control capabilities are achieved with local and central data collection

capability. Backend IT systems allow central collection, analysis and visualisation of data. Depending

on existing monitoring systems at a substation,augmentation of the substation switches that interface

with the communications network is sometimes necessary for deployment of PMUs.

Ausgrids PMU and backend IT implementation has progressed to the point where data is being

collected, stored and analysed from two sites. The remaining four sites are planned for before year

end. Ausgrid has included collected data in this progress report, provided some visualisation to

Ausgrid planners, and has completed an implementation case study..

TransGrids implementation of PMUs has progressed to ordering of five PMUs. Locations have beenselected for priority deployment. Installation, commissioning through to centralised data collection

and data sharing between organisations is planned for the second quarter of 2013.

As data collection proceeds during 2013 the project will move to evaluating the effectiveness in

sensing and responding to stability issues, simulating automated response to failure conditions and

improved decision support to Transmission and Distribution system operations. Specifically the

project will

Continue installation of AMETEK relays in Sydney Ausgrid sits and GE relays at TransGrid

sites

Streamline collection of data to support the investigations and benefits analysis of fault

recording and phasor monitoring

Continue analysis of WAM data with the assistance of Ausgrid and TransGrid business units.

The scope of this analysis will be refined in parallel with the commissioning of new PMUs as

more tests will drive new test requirements

Develop a front-end for the WAM system (synchrophasor data) and the Wide Area Control

simulation

Estimate the bounds of measurement uncertainty in the overall system. This will include an

estimation of the phasor accuracy of the existing CTs and VTs that are being used, the GPS

clock signal accuracy, and the accuracy of the PMU devices themselves

Commence development of a WAM benefits framework for network businesses and the

broader energy industry


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1.2 Trial Design and Architecture

1.2.1 Trial Location

The site selection criteria for substations part of the WAM trial was as follows:

Close to the TransGrid network: This allows phasor measurements to indicate the impact ofupstream network conditions on voltage and current phasors in Ausgrids network. This

resulted in selecting Ausgrid sub-transmission substations closest to bulk supply points

Directly connected to Ausgrid sub-transmission substations: This may also allow for the

review of sub-transmission feeder ratings due to a higher accuracy in measurement of power

being delivered

Geographically dispersed: This will enable measurement of phasors across a wide area.

Figure 1. PMU Deployment

The map displays

TransGrid and Ausgrid

substations that were

included in the scope of

the WAM project.


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Phasor measurement units will be installed in a total of 11 locations, 5 at TransGrid sites and 6 at

Ausgrid sites. Based on the above criteria, the following table lists the substations and feeders that

will be monitored by PMU devices:

Substation Network PMU Device BusVoltage

Comment

Beresfield STS Ausgrid N60 132kV Installed and commissioned

Singleton STS Ausgrid N60 132kV Installed and commissioned

Ourimbah STS Ausgrid TR-2100 132kV

Peakhurst STS Ausgrid TR-2100 132kV

Lane Cove STSS Ausgrid TR-2100 132kV

Mason Park STSS Ausgrid TR-2100 132kV

Newcastle BSP TransGrid N60 330kV Priority install

Tomago BSP TransGrid N60 330kV

Muswellbrook BSP TransGrid N60 330kV Priority install

Waratah West BSP TransGrid N60 330kV

Beaconsfield West BSP TransGrid N60 330kV Priority install

Sydney South BSP TransGrid N60 330kV Priority install

Sydney North BSP TransGrid N60 330kV Priority install

Sydney East BSP TransGrid N60 330kV

Vales Point BSP TransGrid N60 330kV

Tuggerah BSP TransGrid N60 330kV

1.2.2 WAM Trial Components

Wide Area Measurement project components and functions are described below.

Phasor Measurement Units

Wide area measurement systems (WAM) rely on a set of phasor measurement units (PMUs) installed

at diverse locations across an electrical transmission network. A PMU is a device that is connected to

a feeder at a substation and takes current and voltage measurements in order to determine phasors

(as defined by the IEEE C37.118-2005 standard). A phasor is a measurement of the magnitude and

angle of an electrical waveform, either current or voltage. The electric system information is sampled

at very high speeds with individual measured values being transmitted at 50 times per second.

All PMUs in a WAM system each take a phasor measurement at exactly the same time, as they are

synchronised with a common time source (GPS). These time-synchronised phasors are called

synchrophasors. When these sets of synchrophasors are returned to a central location from each

PMU, the state of the network from a wide area perspective can be seen. The angle in a phasor is a

relative unit; therefore for analysis a reference for zero angle is usually selected, generally this is a

voltage phasor. The key piece of information this wide area status of the network gives is the absolute

phase differences between different parts of the network.


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WAM Communications

The commissioned phasor measurement units use Ausgrid's existing fibre MPLS network between

sub-transmission substations and the corporate network to communicate with the central server that

hosts the open PDC application.

Grid Model Validation

The measurements provided by the WAM system can be used to give a more accurate view of the

state of the network, in addition to measurements already provided by protection devices.

It can be used to verify the network model and SCADA data used to perform power flow analysis.

Stability Analysis

Power flow can be predicted under different scenarios with more accurate measurements from the

WAM system.

With more accurate measurements of bus states, the network can be operated closer to the stability

threshold resulting in a higher power transfer, which is particularly important for interconnections.

Early detection of insecure or unstable conditions by the WAM system can provide early detection of

the system trending towards an insecure state (that is, not meeting contingency requirements), or

unstable state, and will assist operators in making informed remedial decisions.

Post Event Analysis

Post event analysis after a disturbance on the network can make use of the WAM measurements to

determine the sequence of events that led to the cause of the disturbance.

If PMUs retain power during a black start (where all generators have had to shut down due to loss of

grid stability) the frequency and phasor angle information can assist system operators to conduct therestoration process.

Phasor Data Concentrator

An open source phasor data concentrator (openPDC) is the system used to manage, process and

respond to dynamic changes in fast moving streaming phasor data. More specifically, the system can

process any kind of data that can be described as time-stamped measured values.

WAM data access and presentation

Besides engineers accessing the data, the requirements of system planners, system operators, and

protection engineers are being gathered in order to develop an appropriate visualisation front-end for

their use of phasor measurement data. System planners are interested in historical data to verify

planning models. System operators are interested in recent history and near real-time data to

complement their existing understanding of the operation of the network that is gained through

SCADA measurements, and some post-fault view of events. Protection engineers are interested in

post event (fault) waveform information.


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1.3 Activities

GE N60 phasor measurement units have been commissioned at Beresfield and Singleton

sites in the Hunter region, monitoring voltages and currents at the 132kV sub-transmission

level. Ausgrids Sydney sites are expected to have AMETEK TR-2100s commissioned over

the next few months TransGrid is progressing designs, with a target commissioning date of early 2013. The first

order of GE N60 relays is at TransGrid for testing. The formal engagement with TransGrid

has begun with 5 sites identified as a priority. Installations are due to complete by February

2013

Ausgrid has completed all the required designs (physical panel layout, protection wiring,

substation communications and interfaces) for the installations in its network

OpenPDC software has been deployed on Ausgrid's central data centre for synchrophasor

data storage, basic visualisation and data exporting

Ausgrid is currently implementing a fibre connection between Transgrid's Sydney South BSP

and Ausgrid's network to facilitate installation of the Transgrid Phasor Data Concentrator

(PDC). This work is scheduled for completion by 31st Oct 2012. Once complete the Transgrid

PDC will transmit the PMU data to the Ausgrid PDC (and vice versa) for comparative analysis


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OpenPDC is the phasor data concentrator that is being used at Ausgrid, and will be used by

TransGrid. The OpenPDC application runs on a central server in the data centre, collecting phasor

data, and providing simple visualisation and reporting tools. (More on openPDC at

http://openpdc.codeplex.com/)

The openPDC Phasor Data Concentrator software system is designed to process streaming time-

series data in real-time. Measured data gathered with GPS-time from many hundreds of input sources

is time-sorted and provided to user defined actions as well as to custom outputs for archival.


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Beresfield STS Voltage and Current Phasor Angle Difference

Phasor measurement data is being received from existing current transformers (CTs) and voltage transformers (VTs) n

and Singleton. The following table depicts the data received in SCADA and in OpenPDC for a moment in time.

From SCADA Calculated From Open PDC

CB Tag Base Feeder MW MVAr PF V-I Angle Ab Angle Ib Angle

Beresfield:132kV:Cb_33806 98R -0.73600006 40.60800171 0.454777142 117.0505961 -

29.0478516

-143.042

Beresfield:132kV:Cb_33812 9NA -2.38399982 -

58.17599869

0.208206205 -

102.0172519

-

29.0478516

72.98218

Beresfield:132kV:Cb_33825 99Y 19.00799942 -

50.97600174

0.349382429 -69.5504536 -

29.0478516

42.03918

Beresfield:132kV:Cb_33794 98N -

27.36000061

53.85599899 0.452925627 116.9315447 -

29.0478516

-

144.9316

Beresfield:33kV:Cb_33837 T1 21.16799927 7.776000023 0.938669755 20.17065411

Beresfield:33kV:Cb_33849 T3 20.59199905 7.343999863 0.941890835 19.62843874


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There are some differences in refresh rates and accuracies of both systems that are likely to be

responsible for some minor differences in the calculated voltage current angles (V-I).

The following phasor plot demonstrates the B phase current phasors at Beresfield relative to the B

phase voltage. This is a reasonably consistent difference during normal operation, varying by 3-4

degrees as loads change.

Figure 2. Beresfield STS and Singleton STS Phasor Angle Difference

Green:98N Phase B Voltage

Red:98N Phase B Current

Black:98R Phase B Current

Blue:9NA Phase B Current

Purple:99Y Phase B Current


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The following phasor plot demonstrates the phasor angle difference between Beresfield and Singleton

that was investigated as part of the case study below.

Figure 3. Phasor angle difference between Beresfield and Singleton

All data from the SGSC trial will be made available via the Information Clearing House. For this

MMR, only a sample data set can be made available, a 5 minute snapshot that demonstrates the

phasor angle difference discussed in the case study. The main limitation to sharing all of the data at

this stage is the high volume of data. Data for phasor angle difference between Beresfield and

Singleton is available in: MMR3_GA_WAM_Beresfield and Singleton phase B.xlsx.

1.4.3 Analysis

Commissioning and integration of phasor measurement devices at Beresfield and Singleton provided

data that was of significant interest to Ausgrid's Subtransmission Planning and System Operations

groups. However, at this stage it has only been presented to Subtransmission Planning using the

views of the data that OpenPDC provides. It is intended that phasor visualisation will be developed tomeet System Operations requirements.

1.5 Lessons Learnt

Installing new relays that have phasor measurement unit functionality fits in well with

Ausgrid's existing protection design capabilities. The design and installation fit into the normal

work of Ausgrid's Control and Protection and Transmission Substations groups, with only the

additional complication of setting up PMU functionality on the relays

Designs in the Hunter were independent of the control and protection systems, and

connected through the MPLS switch to the corporate LAN, which made the overall design

significantly less complicated than a retrofit within a protection system would have been

Green:Beresfield 98N Voltage

Postitive Sequence Phasor

Blue:Singleton 95U Voltage

Positive Sequence Phasor


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It was possible to use existing CTs and VTs, significantly reducing the cost of installation for

the phasor measurement units. However, the complication this introduced is it relies on the

quality of existing measurements used in SCADA and provides the WAM system with less

end-to-end control over the accuracy of the data that is gathered

Despite the fact that this is a trial, a major challenge for the design team was ensuring that

the end-to-end solution had been detailed and agreed by the various business groupsresponsible for the communications and IT systems. It proved to be both challenging and

time consuming to design the interface to the corporate network, understand the bandwidth

requirements, design storage, and fit into the data centre environment. For a large scale

deployment, the required support capabilities and business units involved must be well

understood early in the program

1.6 Case studies

Ausgrid has multiple models that engineers use to predict, evaluate and mitigate problems that the

network is expected to experience. Subtransmission planners maintain and use a network model for

the Hunter area. Off-line load flow analysis is conducted on this model to predict voltage issues andcapacity constraints. Commissioning phasor measurement devices at Beresfield and Singleton helped

Ausgrid planners to validate the subtransmission network model for the Hunter area. Comparing

results of load flow calculations in the subtransmission network model against the synchrophasor

magnitude and angle measurements allowed the planners to ensure that their model reflects the

physical network.

In particular, high load flows (600A) that were measured when the normally open switch was closed at

Rothbury were verified against the synchrophasor measurements that confirmed that a 27 degree

voltage phase shift exists between the Beresfield and Singleton bus bars. Ausgrid's model initially had

predicted that only 200A should flow, but once the model had been updated, 580A flow was

predicted, which better reflected the operational experience.

Future case studies are planned to include a review of the use of phasor measurement data with

internal stakeholders, the Wide Area Control simulation, and collaborative work with TransGrid.


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Glossary of Abbreviations

Abbreviation Term

BSP Bulk supply point

CT Current transformer

LAN Local area network

GE General Electric

GPS Global Positioning System

MPLS Multiprotocol label switching

PDC Phasor data concentrator

PMU Phasor measurement unit

SCADA System control and data acquisition

SGSC Smart Grid, Smart City

STS Sub-transmission substation

VT Voltage transformer

WAM Wide Area Measurement

wide area measurement

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