Synchrophasor Enabled Smart Applications - · PDF fileSynchrophasor Enabled Smart Applications Liang Min, PhD Senior Project Manager, EPRI New York ISO Smart Grid Forum Albany, NY

Synchrophasor EnabledSmart Applications

Liang Min, PhDSenior Project Manager, EPRI

New York ISO Smart Grid ForumAlbany, NY

December 9th, 2010

2© 2010 Electric Power Research Institute, Inc. All rights reserved.

Outline

• Introduction• Synchrophasor Based Voltage Stability Analysis• Application of PMUs for Model Calibration• Summary and Q&A• Appendix – EPRI Synchrophasor Enabled Smart

Applications

3© 2010 Electric Power Research Institute, Inc. All rights reserved. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

0.2

0.4

0.6

0.8

1

Time (seconds)

Vol

tage

(pu

)

Hassayampa 500 kV

MeasuredSimulated H=0.3Simulated H=0.03

Simulated H=0.05Simulated H=0.1Simulated H=0.2Simulated H =0.5

Model ValidationControl Separation

Voltage Stability

Visualization

State Measurement

Operating Boundary

Synchrophasor Enabled Smart Applications

Synchrophasor BasedVoltage Stability Analysis

Liang MinSenior Project Manager

[email protected]


Background

• Voltage Stability Assessment (VSA)– A computer simulation tool, to

help operators monitor andcontrol system voltage stability

• Limitations of Voltage StabilityAssessment (VSA)– VSA relies on the state estimator

to provide steady-state solutions;– Preventive VSA relies on the

selected contingency list (themost critical contingency);

– The accuracy of results dependson the accuracy of modeling thegeneration, load, andtransmission facilities.

Can we use measurement data to calculate voltage stability margins?

New Scotland Voltage Performance vsCentral East Pre-Contingency Power Flow

mailto:[email protected]


Objective

• Demonstrate Measurement Based Voltage StabilityAssessment’s ability to provide real-time voltage stabilitymargins– Utilizing high-sampling rate digital measurement

devices Digital Fault Recorder (DFR), PMU orintelligent electronic devices (IED).


EPRI’s Measurement Based Voltage StabilityAssessment (MB-VSA)

The Maximum Power Transfer

Z_load

=> Z_thev = Z_load

The maximum transfer powerand the critical voltage can beused to measure the proximityto voltage instability:

2 2max max

2 2max max

1

2 1 cos( )

cos

2 1 cos( )

sin

2 1 cos( )

critical criticalV E v E

P E Y p E Y

Q E Y q E Y

Z_thev

0 0.5 1 1.5 2 2.5 3 3.50.5

0.6

0.7

0.8

0.9

1

1.1

1.2VVcritical

0 0.5 1 1.5 2 2.5 3 3.51

1.5

2

2.5

3PloadPmax



“Method for Voltage Instability Load Shedding Using Local Measurement”, U.S. Patent 7603203



PartⅠSource Area

PartⅡSink Area

(Source area) (Sink area)Tie-Lines

a

b

c

PartⅠSource Area

(Source area) (Sink area)

Tie-Lines

RVP+jQE ZThev

“Measurement-Based Voltage Stability Monitoring for Load Center”, U.S.Patent Application Serial No. 12/131,997, filed in May 2008.



Step1. Construct an REI network from the base case power flowsolution and attach it to the buses to be eliminated.

OriginalNetwork …

Step2. Eliminate buses a, c, and c and bus G by Kron reduction andobtain the equivalent network model.

ReducedNetwork …

R

Y2

Yn

Y 1

YR

REI Network

R G

…

0;)/(

1

Gn

iii

RR V

VS

SV

2

*

R

RR

V

SY

niV

SY

i

ii ,,1

2

*

n

iiR SS

1

a

b

c

W. F. Tinney and W. L. Powell, The REI Approach to Power Network Equivalents, Transl.: 1977 PICA Conf.Toronto, ON, Canada, May 1977, pp. 312–320.


Implementation of MB-VSA on the New YorkSystem

Norwalk

Northport

Analytical Study has been completed (funded by NYSERDA Project 10470)


Implementation of MB-VSA on the New YorkSystem

• Central-East/Total-East Interface• Millwood South Interface

Bus Number Bus Name KV TO Inst/PropEPRI MBVSA-

TE/CEEPRI MBVSA-

MS

126262 BUCH N 345 ConEd 1-Proposed (ISO)

126266 DUNWODIE 345 ConEd 1-Proposed (ISO) X

126277 FARRAGUT 345 ConEd 1-Installed X X

126283 GOTHLS N 345 ConEd 1-Proposed (ISO) X X

126297 RAMAPO 345 ConEd 1-Proposed (ISO) X

126298 SPRBROOK 345 ConEd 1-Installed X

128822 E.G.C.-1 345 LIPA 1-Installed X

128847 NWBRG 345 LIPA 1-Proposed (ISO) X X

130750 COOPC345 345 NYSEG 1-Proposed (ISO) X

137452 N.SCOT77 345 Ngrid 1-Proposed (ISO) X

137730 ROTRDM.2 230 Ngrid 1-Proposed (ISO) X

147831 GILB 345 345 NYPA 1-Installed X

ß ß ß UNASSIGNED BUT NEEDED BULK SYSTEM BUSES - - - - - - - - - ß ß ß

137453 N.SCOT99 345 Ngrid Unassigned X


Implementation of MB-VSA onthe New York System

Calculate V, P and Q at the fictitious bususing voltage and current waveforms

Calculate V, P and Q at the fictitious bususing voltage and current waveforms

Calculate the external system’sThevenin Equivalent parameters:

V, P, and Q E and ZThev

Calculate the external system’sThevenin Equivalent parameters:

V, P, and Q E and ZThev

Calculate power transfer limits:E and ZThev Pmax and Qmax

Calculate power transfer limits:E and ZThev Pmax and Qmax

Calculate voltage stability margin:Pmargin =Pmax-P and Qmargin =| Qmax-Q |

Calculate voltage stability margin:Pmargin =Pmax-P and Qmargin =| Qmax-Q |

Measure voltage and current waveformsat the boundary buses (key substations)

of the load center

Measure voltage and current waveformsat the boundary buses (key substations)

of the load center

ExternalSystem

ZLoad

VP+jQE ZThev

INGHAM-E115

New Scotland #77

New Scotland #99

GRAND IS115

ROTRDM.2

Central-East Interface


Simulations on the Central-East Interface

• PMUs were assumed to beinstalled at 5 key substations

• EPRI project team appliedPSS/E to simulate voltageinstability events and used thesimulation data at keysubstations as measurementdata to validate the method

INGHAM-E115

New Scotland #77

New Scotland #99

GRAND IS115

ROTRDM.2

Central-East Interface


Simulations on the Central-East Interface

• Base Case: 2012 Summer Case – ATBA• Contingencies: Tower #41&43-Marcy-Coopers Corners &

Fraser-Coopers Corners.• Dynamic Load Model: Complex load model was used to

model each load bus in NYS (65% motor load for Zone A-K) .


Simulations on the Central-East Interface- Compare ZIP Models and Detailed Models

• CE at 2550MW: LLG @COOPERS ON MARCY-COOPER/FRASER-COOPERS

Voltage recovery orcollapse is influencedby the % of motor load.

ZIP Load ModelReal Power 100% Cons IReactive Power 100% Cons Z

Detailed Load Model – 65% MotorLM15%; SM50%; TEX1%; DL15%; MVA%5 REM14%

Detailed Load Model– 75% MotorLM15%; SM60%; TEX1%; DL5%; MVA%5 REM14%

Variations in % of Motor Loads

Time in Seconds

Voltage inp.u .

mailto:@COOPERS


Simulations on the Central-East Interface –PSS/E Dynamic Simulation

• LLG @COOPERS ON MARCY-COOPER/FRASER-COOPERS

CE at 2550MW

Line Trip

Load Increase in Zone FCE at 3250MW

Load Increase in Zone FCE at 3450MW

Vm<0.95

mailto:@COOPERS


Simulations on the Central-East Interface– MB-VSA Results

• LLG @COOPERS ON MARCY-COOPER/FRASER-COOPERSC e n t r a l - E a s t I n t e r f a c e V o l t a g e S t a b i l i t y M a r g i n

0

5 0

1 0 0

1 5 0

2 0 0

2 5 0

3 0 0

3 5 0

4 0 0

4 5 0

5 0 0

0.5

3

1.0

7

1.6

7

2. 2

7

2. 8

7

3. 4

7

4. 0

7

4. 6

7

5. 2

7

5. 8

6. 4 7

7. 6

8. 2

8. 8

9. 4

10

10

.6

11

.2

11

.8

12

.4

13

13

.6

14

.2

14

.8

T i m e ( S e c o n d )

P M

ar

gin

(M

W)

C e n t r a l - E a s t I n t e r f a c e V o l t a g e S t a b i l i t y M a r g i n

0

5

1 0

1 5

2 0

2 5

3 0

3 5

4 0

4 5

0.5

3

1.0

7

1.6

7

2. 2

7

2. 8

7

3. 4

7

4. 0

7

4. 6

7

5. 2

7

5. 8

6. 4 7

7. 6

8. 2

8. 8

9. 4

10

10

.6

11

.2

11

.8

12

.4

13

13

.6

14

.2

14

.8

T i m e ( S e c o n d )

Q M

ar

gin

(M

va

r)

Line Trip

Load Increase in Zone FCE at 3250MW Load Increase in Zone F

CE at 3450MW

mailto:@COOPERS


Conclusion

• Only needs measurements at keysubstations and Calculates real-time voltagestability margin for a load center

• Help operators track the distance from thecurrent power transfer to its voltage stabilitylimit. This information can be used asdecision support for operator to take actionsto improve voltage stability.

• This monitoring function does not requiremodeling transmission system componentsand does not rely on the SCADA/EMS.

• Can be integrated into a Special ProtectionScheme to perform, e.g., automatic loadshedding.

• Can coordinate multiple load centers toprovide wide-area voltage stability monitoringand control

Norwalk

Northport

Approaches To ModelValidation – Moving

Towards System WideModel Validation

Pouyan PourbeikTechnical [email protected]


INTRODUCTION

Why do we develop power system models?– Because we need to plan the transmission system– Planning requires extensive modeling and analysis– Planning without models and simulation work would be an

insurmountable task given the complexity of modernsystems

– There should be no misconception that computer modelsprovide all the answers – this is certainly not true. Anymodeling effort must also be accompanied by sound“engineering judgment”, since every modeling effort hasassociated uncertainties.

– However, the more diligent we are the more we can reduceor “quantify” the uncertainties for more educated andeconomic decisions.



INTRODUCTION

• Why must we validate models?– A picture is worth a thousand words!

4000

4200

4400

4600

0 10 20 30 40 50 60 70 80 90

4000

4200

4400

4600

Time in Seconds

Simulated COI Power (initial WSCC base case)

Observed COI Power (Dittmer Control Center)

4000

4200

4400

4600

0 10 20 30 40 50 60 70 80 90

4000

4200

4400

4600

Time in Seconds

Simulated COI Power (initial WSCC base case)

Observed COI Power (Dittmer Control Center)

Growing power oscillations during the August 10, 1996 Western-Interconnected System Separation.Top figure is actual recorded power oscillations on the California – Oregon Interface (COI).The bottom trace shows the simulated event based on the then available model (i.e. available priorto the event and subsequent efforts in model validation) (from [2], IEEE © 2006).


WHAT NEEDS TO BE MODELED

• Modeling the Transmission System:– Lines and cables– Shunts (capacitors and reactors)– Transformers (power transformers, phase-shifters)– flexible ac transmission systems (FACTS) and several high-

voltage dc (HVDC) transmission systems• Modeling the Generating Units:

– conventional hydro, steam and gas turbines (still majority)– combined-cycle power plants (significant portion in some regions)– wind turbine generators and imminently the need for modeling

distributed generation (e.g. solar, micro-turbines, fuel-cells etc.) –quickly growing

• Modeling the Load:– Representing the electrical load in the system, which range from

simple light-bulbs to large industrial facilities


TRADITIONAL APPROACH TO VALIDATION

• Transmission model – not really validated (limitedvalidation perhaps for more complex components e.g.HVDC and FACTS using detailed equipment models)

• Generation model – validated in some regions (e.g.WECC) using “staged testing”

• Load model – simplistic,no validation

0 2 4 6 8 10 12 14 16 18 200.995

1

1.005

1.01

1.015

1.02

1.025

1.03

1.035

Spe

ed (

pu)

Time (seconds)

Measured

Fitted


LIMITATIONS OF THE TRADITIONALAPPROACH

• Load modeling is the weakest link in the chain• The most significant challenge with load modeling is its

variability• All equipments are subject to design tolerances and thus

some percentage error (perhaps as much as +/- 10%) inthe quoted electrical and mechanical characteristics.

• Even measurement based “staged testing” has errors(typically, in the order of +/- 5%)

• Variation in equipment behavior such as a change incontrol mode, not captured by staged testing (e.g. unit ison droop one day and on DCS control the next).


WHY DO ALL THIS?

NERC Standards:• MOD-026-1: Verification of Models and Data for

Generator Excitation System Functions• MOD-027-1: Verification of Generator Unit Frequency

Response• MOD-010-0: Steady-State Data for Transmission System

Modeling and Simulation• MOD-012-0: Dynamics Data for Transmission System

Modeling and Simulation…..and others, just to quote a few!


AMBIENT AND DISTURBANCE MONITORINGFOR MODEL VALIDATION


EXAMPLE:VALIDATING GENERATOR MODEL

• Using On-Line Disturbances (Work done and completedby EPRI in 2009 – the PPPD tool)Fitted excitation system and turbine-governor model for large steam-turbine generatorbased on Digital Fault Recorder data for a system wide event (large loss of generation

on the system)

0 10 20 30 40 50 60415

420

425

430

435

440

445

P (

MW

)

Time (seconds)

Measured

Fitted


EXAMPLE:VALIDATING LOAD MODEL

• Load Modeling (Work done and completed by EPRI in2009 – the LMDPPD tool)

Fitted load model for a feeder based on Power Quality meter data capture for atransmission fault.

0 0.05 0.1 0.15 0.2 0.252

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

Time (sec)

Pm

easu

red

vers

us P

eval

uate

d (p

u)

Pmeasured Vs.Pevaluated: Krause

Pmeasured

Pcalculated

0 0.05 0.1 0.15 0.2 0.25-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Time (sec)

Qm

easu

red

vers

us Q

eval

uate

d (p

u)

Qmeasured Vs. Qevaluated: Krause

Qmeasured

Qcalculated


CHECKING THE SYSTEM WIDE MODEL:NOT TYPICALY DONE


APS EVENT – Hassayampa, 28th July, 2003 [3]


BENEFITS OF DISTURBANCE BASEDVALIDATION OF ENTIRE SYSTEM MODEL

• Compare actual response of the model to and actualrecorded disturbance rather than assuming model isadequate when all the pieces have been put together.

• May lead to identifying deficiencies in certain equipmentor regional models

• Can potentially be validated routinely – for example in theWECC suitable system events for model validation havebeen occurring roughly once every 1-2 months.

• Less intrusive, simply implement the monitoringequipment and wait for an event. Do not need to stagetests.

• You can internalize the method and routinely apply tomaintain good system models.


Questions

Liang MinPhone: 650-855-8705E-Mail: [email protected]

34© 2010 Electric Power Research Institute, Inc. All rights reserved. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

0.2

0.4

0.6

0.8

1

Time (seconds)

Vol

tage

(pu

)

Hassayampa 500 kV

MeasuredSimulated H=0.3Simulated H=0.03

Simulated H=0.05Simulated H=0.1Simulated H=0.2Simulated H =0.5

Model ValidationControl Separation

Voltage Stability

Visualization

State Measurement

Operating Boundary

Appendix - Synchrophasor Enabled SmartApplications



Wide Area Power System Visualization and Near Real-time Event Replay Using SynchroPhasor Measurements

• Industry Needs:

– Improving operator situation awareness

• Smart Applications

– Real-time wide area security monitoring

– Near real-time event replay

– Location of disturbance

– Post event analysis

– High performance visualization

• EPRI R&D Engagement:

– TVA, ConEd and NYSERDA (Completed)

– DOE SynchroPhasor Technology Demoproject (to be completed by 09/30/2012)


State Measurement (Evolving from StateEstimation)

• Industry Needs:– Measuring system status directly

instead of estimating them.• Smart Applications:

– State measurement via optimalplacement of PMUs;

– Robust state measurement;– Decentralized state mstimation;– Dynamic/Predicative state

Estimation.• EPRI R&D Engagement:

– Optimal placement of PMUs forNYS funded by NYPA;

– “Next generation state estimation”PID 1016230, 2007;

– “Use of phasor measurement in acommercial (or Industrial) stateestimator”, PID 1011002, 2004. Graphic illustration only


Synchrophasor based Voltage StabilityAnalysis

• Industry Needs:– Real-time voltage stability monitoring and

control.• Smart Application:

– Monitoring system voltage stabilityconditions in real-time;

– Displaying margin information usingvoltage, real power, and reactive power;

– Not relying on state estimator output;– Being integrating into protection and

conrol schemes.• EPRI RD&D Engagement:

– Validation: AEP, Entergy, NYPA,NYSERDA (with NYISO and NY TOs),TPC, and TVA;

– Demonstration: Entergy SGIG, TVA, andTNB.


Visualization of theOperating Boundary

• Industry Needs:

– One single display telling systemoperators: Where we are? How far wecan go? What we could do?

• Smart Application:

– Providing comprehensive boundaryinformation on pre/post-fault stabilitylimits and generation/transmission limits;

– Integrating online measurements (e.g.EMS and PMU data) with simulationtools to provide online operating margin.

• EPRI R&D Engagement:

– TNB.


Synchrophasor based Controlled SystemSeparation

• Industry Needs:

– Intentionally forming islands with a betterchance of surviving;

– System-wide coordination of local out-of-step relays utilizing PMUs.

• Smart Application:

– Where? Potential interfaces consideringgenerator coherency and power balance;

– When? Real-time separation timingdetermination utilizing PMUs;

– How? Coordination of out-of-step relays;

– After? Frequency & voltage control inislands.


Using Synchrophasor Measurements forValidating Power System Planning Models

• Industry Needs:– Comparing actual response of the model

to and actual recorded disturbances.

– Less intrusive, simply implement themonitoring equipment and wait for anevent. Do not need to stage tests.

• Smart Application:– Using Synchrophasor Measurements for

Validating Power System PlanningModels :

• Analysis of any historical PMU datafor model validation;

• Perform a model validation study ifsuitable data is available.

41© 2010 Electric Power Research Institute, Inc. All rights reserved.Image from NASA Visible Earth

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Synchrophasor Enabled Smart Applications - · PDF fileSynchrophasor Enabled Smart Applications Liang Min, PhD Senior Project Manager, EPRI New York ISO Smart Grid Forum Albany, NY