1. Power System Restoration with the Help of a Case-Based Expert System N. Chowdhury Power Systems Research Group University of Saskatchewan Saskatoon, Canada

2. INTRODUCTION Blackouts Rare in a modern power system Cause huge financial losses System Operators Do not gain enough working knowledge and experience on restoration Should be trained to restore their systems

3. INTRODUCTION  Restoration  Operator Training  Expert Systems  Rule-Based: if (Condition 1) Action 1; else if (Condition 2) Action 2; else Action 3;  Case-Based: Identify New Problem Consult Case Library Propose Solution  Why Case-Based Expert Systems ?

4. AN INTELLIGENT TRAINING AGENT

5. OBJECT-ORIENTED GUI

6. CASE-BASED REASONING SUBSYSTEM

7. FUNCTIONS OF THE CBR 'Analyzes and diagnoses the current situation 'Extracts the main features of the current situation 'Determines an index for the situation 'Searches for similar cases in the case library

8. FUNCTIONS OF THE CBR 'Recommends the best matched case 'The best matched case is modified to suit the need 'A restoration plan is suggested

9. SUBUNITS OF THE CBR 'Case Representation Unit 'Situation Recognition Unit 'Case Analyzer 'Case Adapter 'Case Executor 'Case Organizer

10. GRAPHICAL USER INTERFACE: DRAW OBJECT SELECT PASTE DRAG

11. GRAPHICAL USER INTERFACE: EDIT

12. IMPLEMENTATION: CASE LIBRARY

15. SIMULATION: TEST ISLAND FBlackstart: CC and ML units FNon Blackstart: LD unit

16. SIMULATION: STRATEGY  Path Selection n Restoration Power Source n Number of Switching Actions  Test Island n CASE 1: CC - ER - LD n CASE 2: CC - BR - NB - LD n CASE 3: CC - QE - NB - LD n CASE 4: QE - NB - LD n CASE 5: QE - CC - ER - LD

17. SIMULATION: OBJECTIVES  Scenarios Faulty Components  LINES E1L, C3B, Q1N and Q2N Total Blackout  Target n LD Plant Restoration

18. SIMULATION: BLACKOUT

19. SIMULATION: PROPOSAL

20. SIMULATION: RESTORATION

21. ACTION CHECKING

22. A CASE DESCRPTION FOR SASKPOWER

23. POSTDISTURBANCE CONDITIONS 'Nipawin #1 to #3 units off line 'Nipawin #401 to #403 breakers open 'E.B. Campbell #1 to #8 units off line 'E.B. Campbell #401 to #408 breakers open 'CE #916 and #917 breakers open 'Manitoba Hydro available

24. A SOLUTION PROPOSAL

25. CONCLUSIONS 'CBR based systems can be used to train and assist system operators 'GUI will enhance the learning of system operators 'A case library, the vital part of a CBR system, is system specific 'Seed cases have to be developed to initiate the recognition process 'NO RULES: Designing is simple and straightforward