Non-iterative voltage stability analysis methods and prototype

software for multi-path ratingYuri V. Makarov

• WECC JSIS Meeting• Salt Lake City, UT

• September 10, 2014

Project Team

Dr. Bharat Vyakaranam – Research Engineer, Power Systems, PNNLDr. Da Meng – Research Engineer, Power Systems, PNNLDr. Pavel Etingov – Research Engineer, Power Systems,PNNLDr. Tony Nguyen – Research Engineer, Power Systems, PNNLDr. Di Wu - Research Engineer, Power Systems, PNNLDr. Zhangshuan (Jason) Hou – Exploratory data analyses and uncertainty quantification, PNNLDr. Shaobu Wang - Research Engineer, Power Systems, PNNL

Dr. Steve Elbert – High Performance Computing, PNNLDr. Laurie Miller – Research Engineer, Power Systems, PNNLDr. Yuri Makarov – PM, Chief Scientist, Power Systems, PNNLAdvisors:

Dr. Zhenyu (Henry) Huang Dr. Ruisheng DiaoDr. Mark Morgan

Acknowledgements: DOE ARPA-E (Tim Heidel and Sameh Elsharkawy) and DOE OE Office (Gil Bindewald)

Overview - 1

Research ObjectivesNew non-iterative methods for multi-parameter voltage stability assessment (VSA) in near-real-time. Multi-path rating application.Answers will be given: How far the system is from

instability and blackout? What are the most critical

contingencies and system elements?

What needs to be done to increase the security margin in real time?

What is the time remaining for a possible violation? - Future

September 12, 2014 3

Voltage stability boundary of a simple systemand its projections. Source: Hiskens and Davy

Overview - 2Background/Problem:

Different parts of the VS boundary (VSB) correspond to increasingly variablestress directions caused by changing load-generation patterns, contingencies, market forces, cooperation between system operators, variable generation, etc.

September 12, 2014

Computational time becomes critically important for:

Real-time analysesMassive contingency screeningsSimulations of blackouts and cascadingProbabilistic methodsSynchrophasor-based applications, and

Traditional methods (e.g., continuation power flow - CPF) are:

Computationally intensive, Limited by a few stress directions Based on simplifications, Sensitive to initial guesses.

Continuation power flow process: π – predictor; σ – corrector.

Path 1

Path 2

Path 3

Overview - 3

Benefits and Impacts:Enhanced situation awarenessEarly detection of system instability, Improved reliability Actionable information, Prevention of system blackouts, and Better utilization of transmission assets.

Other benefits:VSB visibility for multiple paths and contingenciesDeveloping real-time and HPC applicationsAccurate and flexible quantification of the VS marginsWide-area view on voltage stabilityPotential for predictive/preventive controlPotential for close-loop automatic emergency control systems.

September 12, 2014 5

Security Region

d 1

d 3

d 2

ξd D0

Hd

Security Margin and Control Direction

Security margin ║ξd║ provides situation awareness Control vector ξd provides actionable informationConstraints applied to control parameters and their priorities can be incorporated.

Security Region

d 1

d 3

d 2

ξd D0

Hd

September 12, 2014 6

Approach -1

We are using powerful methods to explore voltage stability boundary (VSB)

Orbiting methodEach iteration produces a new VSB pointWe do not have to repeat continuation power flow for each VSB point!Is very fast and accurate

CPF

1

2-D “Slice” of n-D Voltage Stability Boundary

2

3

Path 1

Path 2

Providing Connectivity With PowerWorld Input: Three System Models Tested

8

Central AmericaInterconnection of Panama, Costa Rica, Honduras, Nicaragua, El Salvador, and Guatemala systems1985 buses2298 branches

California ISO3535 buses4402 branches

Western Electricity Coordinating Council planning model19331 buses22946 branches

-0.2 0 0.2 0.4 0.6 0.8 1 1.2-0.2

0

0.2

0.4

0.6

0.8

1

1.2

Load

at B

us S

ID-2

2

in

100

MW

s

Voltage Security Region in Injection Space - Load at two buses

Simulation Results- Central America

CPF run for one VSB point• 7.6963 s

BOM run • 0.1655 s

Systems Continuation power flow

Boundary orbiting method

Average Time Per Run (s)

Average Time Per Run (s)

WECC2014(19331 buses)

191 16.64

CAISO(3535 buses)

9.6306 1.1010

Central America(1985 buses)

7.6963 0.1655

Simulation Times

Accuracy Comparison With PowerWorld

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Stress direction

Non-iterative Method PowerWorld Accuracy

Sink Load(MW)

Sum(Sink)(MW)

Sink Load(MW)

Sum(Sink) (MW)

%

1 740.08 740.08 738.11 738.11 0.28

2 1188.9 1188.9 1192.8 1192.8 0.82

3 260.58 260.58 261.61 261.61 0.4

4 744.56 1002.4 746.95 1007.0 0.46

Connections with Previous, Existing, and Future Funded Projects and Outreach Activities

Cos

t Sha

ring

University of Sydney, Australia, ARC grantX-ray theorem and

Delta-plane method, 1993-1997

PNNLLDRD project

Further development of Non-iterative voltage stability analysis method

PNNLDOE OE project

Wide-area security region

PNNLBPA project

Wide-area security nomogram

PNNLDOE OE project

Non-iterative voltage stability

PNNLDOE ARPA-E project

Non-wire methodsFY 2013-2015

Further outreach, technology transfer & commercialization:

Utilities and ISOs: BPA, …

Software Vendors: PowerWorld, …

Consulting Companies: Quanta Technologies, …

PNNLCEC/ CERTS /EPG

projectVoltage stability

orbiting procedure

Multi-path Near-Real-Time Path Rating: General Project Progress and Updates

Team: PNNL (Prime): Henry Huang, Ruisheng Diao, Shuangshuang Jin, Yuri

Makarov, Yousu ChenQuanta Technology (Sub-Prime): Guorui Zhang PowerWorld: James WeberBonneville Power Administration: James Wong, Brian Tuck

13

ARPA-E 0670-4106

Transmission congestion cost

Incur significant economic cost2010: >$1.1 billion congestion cost at New York ISO [1] 2010: $ 1.43 billion congestion cost PJM-wide [2]

14 [1] NYISO, “2011 Congestion Assessment and Resource Integration Study”, March 2012[2] PJM, “Congestion and the PJM Regional Transmission Expansion Plan”, Dec. 2011

Means of congestion management

Three traditional means of congestion management (all require capital investment) [3]:

Build more generation close to load centers.Reduce load through energy efficiency and demand reduction programs.Build more transmission capacity in appropriate locations.

Near-real-time approaches:Generation redispatch (additional cost)Dynamic Line Rating (DLR), thermal limited

Validated at RTE, France and Oncor, TXReal-time path rating, security/stability limited

Validated concept at BPA, CAISO and ERCOTNo tools available due to intensive computational requirements using existing techniques

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[3] 2012 National Electric Transmission Congestion Study. David Meyer, U.S. Department

of Energy, August 2012.

Real-time path rating

Current Path Rating Practice and LimitationsOffline studies – months or a year ahead of the operating seasonWorst-case scenarioRatings are static for the operating season

The result: conservative (most of the time) path rating, leading to artificial transmission congestion

Real-Time Path RatingOn-line studiesCurrent operating scenariosRatings are dynamic based on real-time operating conditions

The result: realistic path rating, leading to maximum use of transmission assets and relieving transmission congestion

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Benefits of real-time path rating

17

Increase transfer capability of existing power network and enable additional energy transactions Reduce total generation/consumer costAvoid unnecessary flow curtailment for emergency support, e.g. wind uncertaintiesEnable dynamic transferEnhance system situational awareness

Technical Approach and Objective

1. Develop HPC based transient and voltage stability simulation with innovative mathematical methods

2. Develop HPC based real-time path rating capability with predictability and uncertainty quantification

3. Develop advanced congestion management methods with hierarchical coordination and optimized control

4. Demonstrate the non-wire method on a commercial software platform with real-life power system scenarios

Technology Summary

Metric State of the Art

Proposed

Simulation speed 3-5 times slower than real time

10-20 times faster than real time

Path rating study internal

Months <10 minutes

Uncertainty quantification

No Yes

Asset utilization Conservative Enhanced

Proposed Targets

Project management and coordination

19

Industry Advisory Board: José Conto - Principal Engineer, Electric Reliability Council of TexasAnthony Johnson - Consulting Engineer, Southern California EdisonXiaochuan Luo - Technical Manager, ISO-New EnglandJoshua Shultz - TVADede Subakti - Director, Operations Engineering Services, CAISO

Current activities

Project team actively working on recent deliverablesFast dynamic simulation

Implemented full Y matrix for network solutionTested and compared different linear solvers

Non-iterative voltage stability methodImproved MATLAB code for better accuracy and speedAccuracy validated against a commercial package, PowerWorld Simulator

Developed multiple path rating studies procedureDefined interface functions for software integration

20

Chart 1

Chart 2

Final products

11 1 1 ,1

21 1 2 ,2

1 1 ,

......

......

nn d

nn d

mn nm d m

d d

d d

d d

n n Ln n L

n n L

North of John Day vs. COI + NW/Sierra or PDCI Flow(Summer 2008 N-S Nomogram)

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7000 7100 7200 7300 7400 7500 7600 7700 7800 7900 8000

North of John Day Cutplane Flow (MW)

PDC

I or

CO

I + N

W/S

ierr

a Fl

ow (M

W)

Midpoint - Summer Lake400 MW East to West

Midpoint - Summer Lake400 MW West to East

Midpoint - Summer Lake0 MW

Midpoint to Summer Lake flows are shown in increments of 200 MW

Solid lines are for COI + NW/Sierra limits and Dashed line is for PDCI limit.

Security Region

d1

d3

d 2

ξd D0

Hd

Questions?

24