hume.ictas.vt

1. Smart Grid: Where Computation, Communication and Power Systems Meet Sandeep K. Shukla shukla@vt.edu with Hua Lin, Yi Deng, James Thorp, LamineMili This work was partially supported by NSF grant EFRI-0835879 & an NSF IUCRC - S2ERC Project http://www.hume.ictas.vt.edu

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4. Outline • Motivation • Need for Infrastructure Interdependence Study • Power System & Computing/communication – Smart Grid • Need for Co-Simulation • GECO – Our Co-simulator • Designing New Relaying Scheme with GECO • All PMU-State Estimator with GECO • Experimental Framework • Experimental Results and Interpretations • Conclusions

5. Infrastructure Interdependencies “Our nation’s infrastructures have become increasingly interconnected and interdependent … this creates an increased possibility that a rather minor and routine disturbance can cascade into a regional outage … it also creates new assurance challenges that can only be met by a partnership between owners and operators and government at all levels.” President’s Commission on Critical Infrastructure Protection 1997

6. Examples of Critical Infrastructures • Energy (electric power, oil, natural gas) • Telecommunications • Transportation • Water systems • Banking and finance • Emergency services • Government services • Agriculture • Others

7. * CMU SEI Study

8. What is “Power System”

9. Generation renewable coal natural gas nuclear

10. Transmission substation power tower substation power tower substation power tower substation substation power tower power pole power tower power pole substation substation

11. Distribution industrial residential residential industrial residential residential residential

12. What is “Smart Grid” http://www.elp.com/index/display/article-display/0045209435/articles/utility-products/volume-7/issue-7/product-focus/test-__measurement/measurement-tools.html

13. Smart Grid Vision • Generation: • Micro-grid • Renewable energy • Gas turbines • Transmission: • Wide area monitoring • Wide area protection and control • Real-time state estimation • Distribution Level: • Smart metering • Demand response • Self-healing distribution network

14. Communication Infrastructure

15. Communication Techniques • Communication Link • Telephone • Microwave • Co-axial • Fiber • Power line communication • Communication Network • LAN • WAN • MAN • WLAN

16. A Wide Area Measurement Scenario Control Center

17. Motivation • Smarter Grid entails more Cyber components • Wide area measurement and Control • Communication Infrastructure • New Cyber Security Vulnerabilities • Smart Grid is a Extremely Large Scale Cyber Physical System • ELCPS • Physical Dynamics controlled by Cyber Networked Control • Attack on the networked control can lead to disastrous Physical Dynamics • Need to Study ELCPS • Too large for Analytical Study • Scalable but Accurate Co-Simulation is needed • Need for co-simulation tools • Leveraging Existing Scalable Tools • Study Wide Area Control issues but Security is Extremely Important to Study

18. Co-Simulation for CPS To design a CPS system, engineers need tools to explore possible architectures, protocols, and configurations. Smart Grid engineers should be able to precisely model the power system and the communication network together so that the system behaviors can be suitably predicted. Power System Simulation Synchronization Cyber & Network Simulation

19. Other Power System/Cyber Co-Simulators • EPOCHS: PSLF + NS2 [Cornell] • DEVS method: adevs + NS2 [ORNL] • PowerWorld + RINSE [UIUC] • PowerWorld + OPNET [UIUC] • PowerWorld + NS3 [Ga Tech] • OPNET extension [JiaTong] [1] K. Hopkinson, X. Wang, R. Giovanini, J. Thorp, K. Birman, and D. Coury. Epochs: a platform for agent-based electric power and communication simulation built from commercial off-the-shelf components. [2] J. Nutaro, P. T. Kuruganti, L. Miller, S. Mullen, and M. Shankar. Integrated hybridsimulation of electric power and communications systems. In Proc. IEEE Power Engineering Society General Meeting, pages 1–8, 2007. [3] C. M. Davis, J. E. Tate, H. Okhravi, C. Grier, T. J. Overbye, and D. Nicol. Scadacybersecuritytestbed development. In Proc. 38th North American Power Symp. NAPS 2006, pages 483–488, 2006. [4] D. C. T. C. MalazMallouhi, Youssif Al-Nashif and S. Hariri. A testbed for analyzing security of scada control systems (tasscs). In Second IEEE PES Innovative Smart Grid Technologies Conference, 2011. [5] X. Tong. The co-simulation extending for wide-area communication networks in power system. In Proc. Asia-Pacific Power and Energy Engineering Conf. (APPEEC), pages 1–4, 2010.

20. Continuous Time System Simulation • Discretize differential equations and time

21. Power System Dynamic Simulation

22. Discrete Event System Simulation • Occurrence of events are not uniform • Event-Driven • Scheduler • Event Queue • Event Processing

23. Communication Network Simulation 3 1 2 4

24. Synchronization with errors in EPOCHS Power Communication

25. Global Event-Driven Synchronization Power Communication

26. Implementation of the Co-simulation Framework GECO • PSLF • Power system • Written in Java • Script: EPCL • NS2 • Communication network • Written in C++ • Script: OTcl

27. Co-Simulation Platform Structure

28. GECO To Study All PMU linear state estimator • Global Event-driven Co-simulation

29. Power System Protection • Relays protect power systems when faults happen • Over current • Over voltage • Directional • Distance (Impedance) • Differential • Pilot

30. Distance Relay Protection Zones • Primary: Zone 1 • Backup: Zone 2, Zone 3 • Time-delayed manner for backups: Zone 2(300ms), Zone 3(1s)

31. Problems with Backup Relays • Drawbacks • Long waiting time • Over sensitivity • Hidden failures • However, zone 3 is still needed [1] S. Protection and C. T. Force. Rationale for the use of local and remote (zone 3) protective relaying backup systems. Technical report, North American Electric Reliability Council, 2005.

32. Network-based Backup Relay Protection • Backup distance relays proactively communicate with other relays to obtain wider system visibility and make global protection decision • Software agents take control • Supervisory (master - slave) • Ad-hoc (peer - peer)

33. Supervisory Protection Scheme

34. Supervisory Scheme Operation (Slave)

35. Supervisory Scheme Operation (Master)

36. Ad-Hoc Protection Scheme

37. Ad-Hoc Scheme Operation (Peer)

38. Relay Searching • Find the responsible relay group

39. Searching Algorithm

40. Decision Making • Decision is made by “OR” manner voting • Upper and lower time threshold

41. Co-Simulation Settings • New England 39-bus system • Communication network share same topology with power system • 100Mbps bandwidth and 3ms latency for each communication link • Without background traffic

42. Supervisory Protection on 39-bus System (Case 1)

43. Robustness against primary failure AMS

44. Supervisory Protection on 39-bus System (Case 2)

45. Robustness against hidden failure AMS

46. Supervisory Protection Communication Delay Relay Agent ID

47. Supervisory Protection Communication Delay Analysis

48. Ad-hoc Protection Communication Delay Relay Agent ID

49. Supervisory Protection with Link Failure Relay Agent ID

50. Supervisory Protection Delay with Link Failure