Dynamic Probabilistic Risk Assessment of Cascading Outages

Transcription

1 1 Dynamic Probabilistic Risk Assessment of Cascading Outages P. Henneaux J. Song E. Cotilla-Sanchez Tractebel Engineering Oregon State University Oregon State University Université libre de Bruxelles

2 2 Acknowledgements Paul Hines and Goodarz Ghanavati (University of Vermont) Pierre-Etienne Labeau and Jean-Claude Maun (Université libre de Bruxelles) Daniel Kirschen (University of Washington) Karim Karoui (Tractebel Engineering)

3 3 Introduction Main probabilistic risk assessment tools of cascading outages: static or Quasi-Steady- State (QSS) (power flow equations) Initiating event (initial outage/set of outages) OPA, Manchester model, TRELSS (TransCare), PCM (previous release) Steady-state (power flow/opf) Additional outages (overload,under /overvoltage )? No End of cascade Yes

4 4 Introduction Several cascading phenomena are intrinsically dynamic (angular instability, frequency instability ) Important to consider them in a probabilistic risk assessment of cascading outages? How to consider them?

5 5 Introduction Goals of this presentation Claim that dynamic phenomena should be included in a probabilistic risk assessment of cascading outages Present methodologies of dynamic modeling of cascading outages Discuss the importance of stochastic behavior of protection systems Discuss possible tools: commercial software versus research-grade software

6 6 Agenda Introduction The need for dynamic PRA Methodologies Misoperation of protection systems Commercial and research grade softwares Conclusions

7 7 Agenda Introduction The need for dynamic PRA Methodologies Misoperation of protection systems Commercial and research grade softwares Conclusions

8 8 The need for dynamic PRA Modeling environments required for main cascading mechanisms Mechanism Branch outages by OC and DIST relays Branch outages by thermal failures Unexpected trips due to hidden failures Transient instability Frequency instability Small-disturbance angular instability Modeling environment required Static/Dynamic Static/Dynamic Static/Dynamic Dynamic Dynamic Dynamic

9 9 The need for dynamic PRA Importance of dynamic phenomena in past blackouts: Italy, 2003 Initially, succession of overloads Static: OK

10 10 The need for dynamic PRA Importance of dynamic phenomena in past blackouts? But, after isolation of Italy, frequency instability Static: OK

11 11 The need for dynamic PRA Comparison of static and dynamic simulations Italian Transmission System: events after the loss of a large thermal power plant in Southern Italy Static: OK Static: OK E. Ciapessoni, D. Cirio, and A. Pitto, Cascadings in large power systems: benchmarking static vs. time domain simulation, in Proceedings of the 2014 IEEE PES GM.

12 12 The need for dynamic PRA Comparison of static and dynamic simulations Polish case: impact of N-2 contingencies Underestimation of the probability of large disturbances! J. Song, E. Cotilla-Sanchez, G. Ghanavati and P. Hines, Dynamic Modeling of Cascading Failure in Power Systems, IEEE Transactions on Power Systems, Accepted for publication (IEEE Xplore - Early access, DOI: /TPWRS ).

13 13 Agenda Introduction The need for dynamic PRA Methodologies Misoperation of protection systems Commercial and research grade softwares Conclusions

14 14 Methodologies Deterministic electrical dynamic simulations Deterministic electrical & thermal dynamic simulations Probabilistic electrical dynamic simulations

15 15 Methodologies Deterministic electrical dynamic simulations Deterministic electrical & thermal dynamic simulations Probabilistic electrical dynamic simulations

16 16 Methodologies Deterministic electrical dynamic simulations Only outages due to electrical protection systems are considered Protection systems are considered as perfectly reliable E.g. Pegase Project ( D6.3: deterministic dynamic simulations of cascading outages to train system operators (2012)

17 17 Methodologies Deterministic electrical dynamic simulations Deterministic electrical & thermal dynamic simulations Probabilistic electrical dynamic simulations

18 18 Methodologies Deterministic electrical & thermal dynamic simulations Importance of thermal failures in past cascading outages (especially in the beginning) Need to include this cascading mechanism in a simulation OSU & UVM developed an ad-hoc simulator, COSMIC (

19 19 Methodologies Deterministic electrical dynamic simulations Deterministic electrical & thermal dynamic simulations Probabilistic electrical dynamic simulations

20 20 Methodologies Probabilistic electrical dynamic simulations Protection systems do not always act as expected (e.g. hidden failures) Need to include stochastic behaviors of protection systems in the dynamic simulation probabilistic dynamic simulation Probabilistic dynamic simulations initially developed at Iowa State University for operational defense of cascading events (see Q. Chen, The probability, identification, and prevention of rare events in power systems, PhD thesis, 2003) Probabilistic dynamic simulator under development by Tractebel Engineering, based on the deterministic simulator Eurostag (

21 21 Methodologies Example of a deterministic electrical & thermal dynamic simulation (COSMIC) Polish test system Events after a N-2 contingency J. Song, E. Cotilla-Sanchez, G. Ghanavati and P. Hines, Dynamic Modeling of Cascading Failure in Power Systems, IEEE Transactions on Power Systems, Accepted for publication (IEEE Xplore - Early access, DOI: /TPWRS ).

22 22 Methodologies Example of a deterministic electrical & thermal dynamic simulation (COSMIC) Polish test system Risks induced by N-2 contingencies for different load models J. Song, E. Cotilla-Sanchez, G. Ghanavati and P. Hines, Dynamic Modeling of Cascading Failure in Power Systems, IEEE Transactions on Power Systems, Accepted for publication (IEEE Xplore - Early access, DOI: /TPWRS ).

23 23 Methodologies Example of a probabilistic electrical dynamic simulations (Eurostag) Reliability Test System Consideration of protection system misoperations (measurement errors, circuit breaker failures, timer failures ) P. Henneaux, P.-E. Labeau, J.-C. Maun and L. Haarla, A two-level Probabilistic Risk Assessment of cascading outages, IEEE Transactions on Power Systems, Accepted for publication.

24 24 Agenda Introduction The need for dynamic PRA Methodologies Misoperation of protection systems Commercial/research grade software Conclusions

25 25 Misoperation of protection systems Protection systems not perfectly reliable Missing trips/unwanted trips Importance to consider these misoperations in dynamic simulation of cascading outages? For a specific initiating event in precise precontingency steady state, obviously important If all protections act as expected, one unique outcome If possible failures, different outcomes But impact on the global risk?

26 26 Misoperation of protection systems Impact of misoperations on a small system Adaptation of Kundur s two-area test system, Monte Carlo simulation (sampling of thresholds & failures)

27 27 Misoperation of protection systems Impact of misoperations on a large system Polish test case (2383-bus test system), idem

28 28 Agenda Introduction The need for dynamic PRA Methodologies Misoperation of protection systems Commercial/research grade software Conclusions

29 29 Commercial/research-grade software Commercial software Pros Available models for a large number of modern power systems components Optimized numerical efficiency Cons Black box, difficult to adapt Difficult to integrate in a HPC cluster Cost Example Eurostag ( Research-grade tool In-depth access to the source code, and allows precise tuning of modeling/control assumptions Easy to integrate in a HPC cluster Cost Models not always available for each power system component (e.g. HVDC, wind farms ) Weaker numerical efficiency COSMIC (

30 30 Agenda Introduction The need for dynamic PRA Methodologies Misoperation of protection systems Commercial/research grade software Conclusions

31 31 Conclusions Importance of dynamic mechanisms in cascading outages Especially in the latter stage Different degrees of complexity in existing models Methodologies still under development (HRs needed!) Importance of misoperation of protection systems? Not yet clear