expedited system impact assessment report...unit with an abb unitrol-6000 full static excitation...
TRANSCRIPT
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Expedited System
Impact Assessment
Report
CONNECTION ASSESSMENT & APPROVAL PROCESS
CAA ID: 2012-EX594
Project: Mcphail G2 Excitation System Upgrade
Applicant: Brookfield Renewable Power
Market Facilitation Department
Independent Electricity System Operator
Date: August 31st 2012
Document Name Expedited System Impact Assessment Report
Issue Final
Effective Date August 31st 2012
Expedited System Impact Assessment Report Table of Contents
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Table of Contents
Table of Contents .....................................................................................................3
Executive Summary .................................................................................................4
Requirement for Conditional Approval for Connection. ................................................. 4
1. Project Description ...........................................................................................5
2. Data Verification ................................................................................................6
2.1 Generator ......................................................................................................... 6
2.2 Excitation System ............................................................................................. 7
2.3 Power System Stabilizer ................................................................................... 8
3. Assessments ................................................................................................... 10
3.1 Excitation System Performance ...................................................................... 10
3.2 Dynamic Study Results ................................................................................... 15
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Executive Summary
The IESO recommends that a Notification of Conditional Approval for Connection be issued for the
replacement of the excitation system at Mcphail G2, subject to implementation of the requirements outlined in
this report. The proposed replacement of the excitation system at Mcphail G2 is expected to have no material
adverse impact on the reliability of the integrated power system.
Requirement for Conditional Approval for Connection. The connection applicant must complete the IESO Facility Registration/Market Entry process in a timely
manner before IESO final approval for connection is granted.
The applicant is required to ensure that the performance of the equipment that is eventually supplied and
installed at G2 of Mcphail GS is similar to or exceeds the performance of the existing system. As soon as the
commissioning tests are completed and actual data is available, the connection applicant is required to provide
an updated model of the excitation system and the PSS of Mcphail G2. Using these data the IESO will perform
studies to verify the behavior of the excitation system and establish the need for any new control and
adjustment, as part of the Facility Registration/Market Entry Process.
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1. Project Description
Brookfield Renewable Power-Wawa Hydro Operations plans to replace the excitation system for Mcphail G2
unit with an ABB Unitrol-6000 full static excitation system due to equipment obsolescence.
The replacement is scheduled to be done in September, 2012.
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2. Data Verification
The applicant provided the dynamic models for generator, excitation system, and PSS as follows.
2.1 Generator Table 1: Generator Dynamic Data – Model GENSAE
CONs Value Description Units
J 1.97 T’d0 (sec) (>0) Sec
J+1 0.0587 T"d0 (sec) (>0) Sec
J+2 0.1105 T"q0 (sec) (>0) Sec
J+3 1.71 Inertia, H MW-s/MVA
J+4 0 D, Speed damping p.u
J+5 1.14 XD p.u
J+6 0.77 XQ p.u
J+7 0.497 X’D p.u
J+8 0.13 X"D = X"Q p.u
J+9 0.1 XL p.u
J+10 0.197 S (1.0) p.u
J+11 0.717 S (1.2) p.u
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2.2 Excitation System
Table 2: Excitation System Data – Model ESST1A
Figure 1: ESST1A Block Diagram
CONs Value Description
J 0.01 TR (sec)
J+1 99 VIMAX
J+2 -99 VIMIN
J+3 1 TC (sec)
J+4 3 TB (sec)
J+5 0.02 TC1 (sec)
J+6 0.02 TB1 (sec)
J+7 450 KA
J+8 0.0 TA (sec)
J+9 5.94 VAMAX
J+10 -5.23 VAMIN
J+11 5.94 VRMAX
J+12 -5.23 VRMIN
J+13 0.077 KC
J+14 0 KF
J+15 1.0 TF > 0 (sec)
J+16 20 KLR
J+17 3.42 ILR
Description ICONS Parameter Value
Alternate
UEL inputs IC UEL (1,2 or 3) 1
Alternate
Stabilizer
Inputs
IC + 1 VOS (1 or 2) 1
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2.3 Power System Stabilizer Table 3: PSS Data – Model PSS2A
Description CONS Parameter Value Units
First stabilizer input code IC ICS1 1 Rotor speed deviation (pu)
First remote bus number IC+1 REMBUS1 0 Sec
Second stabilizer input code IC+2 ICS2 3 Sec
Second remote bus number IC+3 REMBUS2 0 Sec
Ramp tracking filter order IC+4 M 5
Ramp tracking filter order IC+5 N 1
Washout time constant J Tw1 (>0) 10 Sec
Washout time constant J+1 Tw2 10 Sec
Filter time constant J+2 T6 0 Sec
Washout time constant J+3 Tw3 (>0) 10 Sec
Filter time constant [block bypassed] J+4 Tw4 0 Sec
Washout time constant J+5 T7 10 Sec
Gain J+6 KS2 2.92
Gain J+7 KS3 1 Sec
Ramp-tracking filter time constant J+8 T8 0.5 Sec
Ramp-tracking filter time constant J+9 T9 (>0) 0.1 Sec
Stabilizer gain J+10 KS1 10 Sec
Phase lead time constant J+11 T1 .03 Sec
Phase lag time constant J+12 T2 .01 Sec
Phase lead time constant J+13 T3 .03 Sec
Phase lag time constant J+14 T4 .01 Sec
Output limits J+15 VSTMAX .05 pu Etref
Output limits J+16 VSTMIN -0.05 pu Etref
Generator Apparent Power MBASE 6.927 MVA
Output limits H 1.71 MW-s/MVA
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Figure 2: PSS2A Block Diagram
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3. Assessments
3.1 Excitation System Performance
Excitation system performance for Mcphail G2 was checked to verify the exciter’s positive and negative
ceilings, positive ceiling at rated terminal voltage and 160% of rated field current, and voltage response time.
Mcphail G2 rated field voltage (Efdrated) was determined from the proposed excitation system model provided by
the applicant. The unit ratings are shown in Table 4.
Table 4: Mcphail G2 Ratings
3.1.1 Field Voltage Ceiling Test
Appendix 4.2 in the Market Rules lists the requirements for exciters on generation facility directly connected to
the IESO-controlled grid to have positive and negative ceilings not less than 200% and 140% of rated field
voltage at rated terminal voltage and rated field current, and a positive ceiling not less than 170% of rated field
voltage at rated terminal voltage and 160% of rated field current.
3.1.1.1 Positive ceiling at rated field current
Simulations show that the proposed excitation system’s positive ceiling response meets the Market Rule
requirement.
The Response Ratio test in PSS/E was conducted to evaluate the positive ceiling voltage for the proposed
excitation system as well as the current one. The generator is first initialized to its rated MVA at rated power
factor. At t = 0, the voltage set point is raised suddenly in order to reach the exciter’s positive ceiling voltage as
quickly as possible. The response plot is shown in Figure 3.
It can be observed that the rated field voltage (Efd rated) is 2.05 pu and the positive ceiling voltage is 5.75 pu.
Therefore, the positive ceiling voltage exceeds 200% of the rated field voltage.
Description Value Units
Rated Voltage 1.0 pu
Rated Active Power 6.1 MW
Maximum Reactive Power 3 Mvar
Rated Field Voltage 2.05 pu
Rated Field Current 2.05 pu
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Figure 3: Positive Ceiling
3.1.1.2 Negative ceiling at rated field current
Simulations show that the proposed excitation system’s positive ceiling response meets the Market Rule
requirement.
A Response Ratio test was used to evaluate the negative ceiling voltage for the proposed excitation system. At
t=1, the voltage set point is dropped suddenly in order to reach the exciter’s negative ceiling voltage as quickly
as possible. The response plot is shown in Figure 4.
It can be observed that the rated field voltage (Efd rated) is 2.05 pu and the negative ceiling voltage is -5.23 pu.
Therefore, the negative ceiling voltage meets the Market Rule requirement of 140% of the rated field voltage.
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Figure 4: Negative Ceiling
3.1.1.3 Positive ceiling at 160% field current
Market rules requires that, at rated terminal voltage the excitation system should be able to reach the positive
ceiling of 170% of Efd rated when the field current is 160% of Ifd rated.
Test results depicted in Figure 5 shows that excitation system reaches Efd positive ceiling of 5.75 p.u (280% of
Efd rated), at the rated terminal voltage when field current is 160% of the Ifd rated and hence meets the requirement.
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Figure 5: Positive Ceiling at 160% Field Current
3.1.2 Field Voltage Response Time
Appendix 4.2 in the Market Rules lists the requirements for exciters on Generation facility directly connected to
the IESO-controlled grid to have a voltage response time to either ceiling not more than 50 ms for a 5% step
change from rated voltage under open-circuit conditions and a linear response between ceilings.
Based on the Market Rule requirement, for the +5% step response, the field voltage is required to reach 200% of
the rated field voltage within:
RTOC POS = 50* (1.95 Efd rated - Efd oc)/ (1.95 Efd rated - Efd rated) =
= 50* ((1.95*2.05) –1.16)/ ((1.95*2.05) – 2.05) = 72.85 ms
and for the -5% step response, the field voltage is required to reach -140% of the rated field voltage within:
RTOC NEG = 50* (1.28 Efd rated + Efd oc)/ (1.28 Efd rated + Efd rated) = 40.48 ms
Open circuit tests using PSS/E were conducted to evaluate the voltage response time for the proposed excitation
system. The generator is initialized to rated terminal voltage on an open circuit. At t = 0, the voltage set point is
increased or reduced by 5% to evaluate the excitation system’s voltage response time. The response plots
associated with the open circuit test are shown in Figure 6 and Figure 7. The initial open circuit voltage (Efd oc) is
1.16 pu.
Figure 6 shows that the proposed excitation system reaches an Efd of 5.81 pu, within 8.2 ms.
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Figure 6: Positive Ceiling Voltage Response Time
Figure 7 shows that the proposed excitation system reaches an Efd of -5.1 pu, which is greater than -140% of the
rated field voltage, within 3.2 ms.
Figure 7: Negative Ceiling Voltage Response Time
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3.2 Dynamic Study Results
Transient stability analysis was carried out to investigate the impact of the replacement of the excitation system
of G2 at Mcphail GS on the reliability of the IESO-Controlled grid.
The 2014 summer basecase was used as a starting point for the analysis. The transient stability analysis was
performed with all transmission elements in service. A LLG fault on the 115 kV circuit High Falls #1 at
Anjigami TS with normal clearing time was applied. Upon clearing of this fault, circuit High Falls #1 would be
tripped and all the generators connected to Da Waston TS would remain connected to the system.
The rotor angle of generator G2 at Mcphail GS was monitored for two cases: 1) with the PSS operating, and 2)
without the PSS operating. The results displayed in Figure 8 show that the presence of the PSS helps damping
the oscillations in the rotor angle of the machine. Moreover, the results displayed in Figure 9 show that the
generators in the vicinity of Mcphail GS have a stable performance and the oscillations are well damped.
Therefore, based on the transient stability study results it can be concluded that the proposed replacement of the
exciter of G2 at Mcphail GS would not adversely impact the reliable operation of the IESO-controlled grid.
Figure 8: Rotor Angle of G2 at Mcphail GS with and without the PSS
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Figure 9: Rotor Angles of Surrounding Units
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