Generic Models for Static VAr...

Generic Models for Static VAr Systems

Pouyan [email protected] HVDC & FACTS ConferenceAugust 30, 2011

2© 2011 Electric Power Research Institute, Inc. All rights reserved.

THE DEFINITION OF AN SVS

• Static Var System = any combination of power electronic controlled/switched shunt device + coordinated mechanically switched shunt elements

(reproduced from [3], © IEEE 2005)

TCR

TSC

MSC

Control Strategy

Vbus

Vref

slope


THE TECHNOLOGIES

• Basic building blocks:

(reproduced from [3], IEEE © 2006)

SVC STATCOM


WORK THAT WAS DONE

• EPRI Worked in collaboration with the WECC SVC TF

• WECC SVC TF Chair: Janet Kowalski, SCE

• Goal was to develop new models for SVS for– powerflow planning studies– System stability planning studies

• Share results publicly to get the models into the commercial tools (e.g. GE PSLF®, Siemens PTI PSS®E, PowerWorld, PowerTech Labs etc.)

• Participants in the group:– ABB, EPRI, GE, PG&E, Mitsubishi, NERC, SCE, Siemens, TEP,

WECC– Many others provide comments (S&C, AMSC, etc.)– See full TF report [1]


OLD MODELS vs NEW MODELS

• Previously many models in commercial tools (such as GE PSLF® and Siemens PTI PSS®E) for modeling SVCs and STATCOMS.

• Although these models have served a great purpose, the technology has since advanced

• The old standard library models could not (typically):– Model relevant protection and short-term ratings– PI regulators– Slow-susceptance regulator– Coordinate switching of MSSs– Deadband (if implemented)– In power flow model slope, coordinate MSS switching and slow-

susceptance regulator• Not being able to model the above means not really being able to

assess the functionality of modern equipment in planning studies• The new models do capture these (and some more) functionalities


WHAT IS MODELED IN THE NEW MODELS

– The voltage regulator– The coordinated switching logic for MSSs (B based

switching; V base is a separate complementary model)

– The slow-susceptance regulator (optional)– Deadband control (optional)– SVC slope/droop (non-linear, optional)– SVC limits, over- and under-voltage strategy and

voltage trip set points (protection)– Any short-term rating capability– Power Oscillation Damper is a separate

complimentary model


WHAT IS NOT MODELED

– The TCR and TSC current limits – Secondary Voltage Limitation (may in some cases need to be

modeled, e.g. some STATCOM applications)

– Gain scheduler – Main other controls and details (cooling system

controls etc.) that have little to no bearing for system dynamic performance studies.


VI CHARACTERISTIC

STATCOM SVC

(not to scale, explanation tool only)

Cap. ICap. I Ind. IInd. I

V

V


TERMINOLOGY

• SVSMO1 – model of a TCR based SVS

• SVSMO2 – model of a TSC/TSR based SVS

• SVSMO3 – model of a VSC based SVS

DYNAMIC MODELS


THE GENERIC SVSMO1 MODEL

Vsig

+-

S0 Vemin

BmaxVemax

Bsvc (p.u.)Vbus

Linear or Non-Linear Slope Logic

1 + sTb1

1 + sTc1

+S4

1 + sTb2

1 + sTc2

S2

1 + sT2

1

S1

s Kiv

Kpv+

Bmin

X

MSS SwitchingLogic based on

B

MSS1......

MSS8

Isvc

DeadbandControl

(Optional)

VrefmaxVrefmin

+

Vrmax

S3

s Kis

Kps+

Vrmin

+

++

Bref control logic

BSVC (MVAr)

Bref

-+

Berr Vsched

Verr

Vr

SVC over-and under-

voltage tripping function

B

VcompVr

Vref

Over Voltage Strategy,Under Voltage

Strategy& Short-Term Rating

externally controllable

externally controllable

pio2

pio1



Vsig

+-

S0Vemin

BmaxVemax Bsvc (p.u.)

Vbus

Linear or Non-Linear Slope Logic

1 + sTb1

1 + sTc1

+S4

1 + sTb2

1 + sTc2

S2

1 + sT2

1

S1

s Kiv

Kpv+

Bmin

X

MSS SwitchingLogic based on

B

MSS1......

MSS8

Isvc

VrefmaxVrefmin

+

Vrmax

S3

s Kis

Kps+

Vrmin

+

++

Bref control logic

BSVC (MVAr)

Bref

-+

Berr Vsched

Verr

Vr

SVC over-and under-

voltage tripping function

B

VcompVr

Vref

Over Voltage Strategy,Under Voltage

Strategy& Short-Term Rating

pio2

pio1Look-up

Tabledbe-dbe

dbb-dbb

Look-up tablefinds B closest to Bcommand

(Bcommand)

POWERFLOW MODELS


TCR BASED SVS – SVSMO1

• Model slope • Allow seamless connection of shunt model to dynamics

model• Model MSS switching• Emulate slow-susceptance regulator• EMULATION – cannot exactly predict sequence


TSC/TSR BASED SVS – SVSMO2

• Key is to be able to model combination of TSC/TSRs• Model coordinated MSS switching• Allow seamless connection of shunt model to dynamics

model


VSC BASED SVS – SVSMO3

• Model slope • Allow seamless connection of shunt model to dynamics

model• Model MSS switching


REVIEW OF MODELS AND TESTING

• Extensive testing done by:– EPRI (on svsmo1, svsmo2 and svsmo3)– Mitsubishi (on svsmo1)– GE (on svsmo1, svsmo3)– Siemens PTI (on svsmo1, svsmo2)

MODEL VALIDATION DONE BY EPRI


VALIDATION USING DFR RECORDING (SVSMO1) (similar to EPRI PPPD approach [2])


VALIDATION USING DFR RECORDING (SVSMO1)


CONCLUSIONS

• Three new SVS models developed

• Approved within WECC

• Are now implemented and available in the latest versions of GE PSLF® and Siemens PTI PSS®E; also have sent code to PowerWorld and PowerTech Labs

• Tested and validated against measured disturbance data

• Vendors were major participants in the effort

• EPRI held a successful workshop on these models in Charlotte, NC in September 2010


REFERENCES

[1] Generic Static Var System Models for the Western Electricity Coordinating Council, WECC SVC TF, April, 2011 (www.wecc.biz)

[2] P. Pourbeik, “Automated Parameter Derivation for Power Plant Models From System Disturbance Data”, Proceedings of the IEEE PES General Meeting, Calgary, Canada, July 2009.

[3] P. Pourbeik, M. P. Bahrman, E. John and W. Wong, “Modern Countermeasures to Blackouts”, IEEE Power and Energy Magazine, Vol. 4, No. 5, September/October 2006,pp. 36-45.


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