dynamic voltage support with the rector svc in...

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Power Electronics/FACTS Installations to Improve Power System Dynamic PerformancePanel Session Presentation on

Dynamic Voltage Support with the Rector SVC in California’s San Joaquin Valley

Presented by

Anthony Johnson, SCEDan Sullivan, MEPPI

April 23, 2008

2008 IEEE/PES Transmission and Distribution Conference & ExpositionChicago, Illinois

MITSUBISHI ELECTRICPOWER PRODUCTS, INC.MITSUBISHI ELECTRICPOWER PRODUCTS, INC.

Presented by: Anthony Johnson, SCE

Dan Sullivan, MEPPIFACTS PANEL SESSION, IEEE/PES T&D Conf. & Expo, Chicago, IL - April 23, 2008Dynamic Voltage Support with the Rector SVC in California’s San Joaquin Valley 2

Transmission System in Big Creek Corridor

Rector to Big Creekapprox. 60 -80 miles

Approximately 15-20 miles of new 230 kV line looping in Rector Substation into Springville-Big Creek No. 3, 230 kV line tobe installed in 2009

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System AssessmentCorridor Limitations

Age related reliability issuesLarge number of splices in transmission conductors are failingAbsence of transmission towers mean imbalanced loading between phasesTransmission losses during peak utilizationBi-directional power flows in system designed for delivery of hydro power to southern area

Transient Voltage Stability Limitations

Outage of either line between Rector and Big Creek causes low transient voltage at Rector under heavy load conditionsLow transient voltage due to a high percentage of induction motor load served by Rector Without mitigation the low-voltage condition may violate WECC transient voltage dip reliability requirements

Solution200 Mvar SVC for dynamic voltage support and coordinated voltage control

Loop the Big Creek-Springville 230 kV line through Rector substation



Requirements for Voltage Control

Limit the transient voltage dips during major system disturbances

Regulate the 230 kV steady-state voltage at Rector while preserving sufficient SVC dynamic range

Control a local 230 kV, 79 Mvar capacitor bank

Coordinate the 230 kV Big Creek Generating Station operating voltage with the SVC’s control

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Rector SVC Rating and Design

Rating-120/+200 Mvar continuous at 230 kVLoss of one TCR branch does not reduce the SVC inductive Mvar output by more than 50% (i.e. -60 MVAr)Largest TSC branch shall not result in a voltage rise (at Rector 230 kV) greater than 2.0% under minimum fault dutyAvailability: 98.5% forced outage

TCR/TSC/FC Based DesignDirect LTT-based TCR/TSC valves3rd, 5th, 7th harmonic filtersAuto-reconfigurable degraded mode

ApplicationDynamic voltage/var control

Coordinated ControlLocal 79 Mvar, 230 kV shunt capacitor230 kV Big Creek Generating Station operating voltage



Rector SVC DesignRector 230 kV Bus

200 MVA Total3 x 1-phase

+ Spare230 kV to 9.5 kV

M

9.5 kV kV Bus

M

TSC# 2

+ 40 MVAr

M

TSC# 3

+ 40 MVAr

M

TSC# 3

+ 40 MVAr

TCR# 1- 70

MVAr

M M M

TCR# 2- 70

MVAr

TCR# 3- 70

MVAr

3rd 5th 7th

Harmonic Filters

# 1+ 40

MVAr

M

3rd 5th 7th

Harmonic Filters

# 2+ 40

MVAr

M

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Rector SVC Site

Main Coupling Transformers (4 x 1-phase)

Thyristor-Controlled Reactors (TCRs)

Harmonic Filter Banks

Thyristor Valves

Cooling

Thyristor-Switched Capacitors (TSCs)

Yard Area - 255 ft x 200 ft(Excluding Building)



Rector SVC Site

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Rector SVC Site



Coordinated Voltage/Var Control Scheme

The SVC’s primary function is to control the dynamic voltage change at the Rector 230 kV bus (REC-AVR). The SVC steady-state control:

Operates the steady-state reactive power output (SVC-AQR), Provides supplementary regulation of the 230 kV Big Creek #3 bus voltage via phasor measurement unit (PMU) (BC-AVR), and Controls a 79 MVAR, 230 kV shunt capacitor in the Rector substation (SC-Control).

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V-Q Characteristics of the Rector SVC Coordinated Control

Since three different control loops (REC-AVR, SVC-AQR, and BC-AVR) functiontogether in the steady-state coordinated control, the steady-state SVC output shouldbe controlled based on the V-Q characteristics, in the following order of priority:

1) Maintain Big Creek #3’s 230 kV bus voltage within its upper (VH2) and lower (VL2) limits (BC-AVR) and SVC steady-state output within QCmax and QLmax(SVC-AQR)

2) Maintain Rector 230 kV bus voltage within its upper (VH1) and lower (VL1) limits with Priority #1 maintained (REC-AVR)

3) If Big Creek #3 230 kV bus voltage goes lower than VL2, the SVC should control it within VL2 while maintaining the first two priorities



Conclusion

The Rector SVC was successfully designed, installed, tested, and commissioned in approximately 14 months with an in-service date of June 2007.The application of the Rector SVC and steady-state coordinated controls provide improved short-term voltage stability and dynamic voltage support in the Big Creek Corridor.

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Rector and Big Creek Voltage Profile with the SVC Out-of-Service

Reactive

Power (M

var)

Vol

tage

(kV

)

Time

SVC Output

Big Creek Voltage

VmaxVavgVmin

Rector Voltage

VmaxVavgVmin

October 21, 2007



Rector and Big Creek Voltage Profile with the SVC In-Service

Reactive

Power (M

var)

Vol

tage

(kV

)

October 28, 2007Time

SVC Output

Big Creek Voltage

VmaxVavgVmin

Rector Voltage

VmaxVavgVmin

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Impact of SVC on Capacitor Switching

Big Creek

Rector

Area Voltages

Rector 79 MvarCapacitor bank

switches offSVC is in-service



Rector Example: 6-14-07 (pre-SVC) vs. 8-30-07 (post-SVC)

Rector 6-14-200766-kV fault triggered (breaker internal fault)150 MW load reduction (125 MW w/no apparent CB operation)Disturbance isolated to Rector radial subtransmission system

Rector 8-30-200766-kV fault triggered (lightning)120 MW load reduction (w/no apparent CB operation)Disturbance isolated to Rector radial subtransmission systemRector SVC (+200/-120 MVAR) was in service and operated as designed during the Rector system disturbance:

Reached full boost (+200 MVAR) during low voltage eventReached full buck (-120 MVAR) during post-event overvoltage

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Impact of the Rector SVC:6-14-07 (pre-SVC) vs. 8-30-07 (post-SVC)

Magunden Substation Voltage Comparison(Rector Substation Events 6-14-07 and 8-30-07)

220

222

224

226

228

230

232

234

236

238

240

-5.00 0.00 5.00 10.00 15.00 20.00 25.00

Time (seconds)

Mag

unde

n Vo

ltage

(kV)

Rector 8-30-2007 event (POST-SVC) Rector 6-14-2007 event (PRE-SVC)

The Rector SVC had the apparent effect of reducing the magnitude & duration of the fault-induced slow voltage recovery

6-14-2007 (pre-SVC)

8-30-2007 (post-SVC)

NOTE: Voltages shown were measured ~70 miles south of Rector Substation (actual low voltage event was of greater magnitude at Rector substation itself)

Magunden bus voltage



August 30, 2007 AC Stall Event: Rector Voltage

The PMU at Rector was installed as part of the SVC installation. Therefore, events prior to the installation do not have the Rector voltage available.

214.2

218.6

223.0

227.3

231.7

236.1

10:20:35.00 10:20:45.80 10:20:56.60 10:21:07.40 10:21:18.20 10:21:29.00 10:21:39.80P a c i f i c T i m e

V o

l t a

g e

(k V

)

Rector bus voltage

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Voltage Calibration Need

220

225

230

235

240

245

250

236.

28

4/2/

2007

4/4/

2007

4/6/

2007

4/8/

2007

4/9/

2007

4/11

/200

7

4/13

/200

7

4/15

/200

74/

16/2

007

4/18

/200

74/

20/2

007

4/22

/200

74/

24/2

007

4/25

/200

74/

27/2

007

4/29

/200

75/

1/20

07

5/3/

2007

5/4/

2007

5/6/

2007

5/8/

2007

5/10

/200

7

5/12

/200

75/

13/2

007

5/15

/200

75/

17/2

007

Big Creek Average VoltageRector Average Voltage

Vol

tage

(kV

)

Date and Time

Big Creek bus voltage

Rector bus voltage

Calibration adjustment



Questions?

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Reference Slides



Transmission System Conditions

Transmission Line Voltage: 230 kV, (0.96 PU to 1.04 PU)

Short Circuit MVA:Maximum = 3,625Minimum = 2,151

Allowed Max. Switching Step 2% (0.02 x 2,151 = 43 Mvar max.)

Ambient Conditions:Elevation 350 FeetMaximum Temperature 50 Degrees C (45 Deg. 24 hr. Avg.)Minimum Temperature - 20 Degrees C

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Rector SVC Site

Yard Area255 ft x 200 ft

(Excluding Building)

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