Power System Restoration with the Help of a Case-Based Expert System N. Chowdhury Power Systems Research Group University of Saskatchewan Saskatoon, Canada
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
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 ?
AN INTELLIGENT TRAINING AGENT
OBJECT-ORIENTED GUI
CASE-BASED REASONING SUBSYSTEM
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
FUNCTIONS OF THE CBR 'Recommends the best matched case 'The best matched case is modified to suit the need 'A restoration plan is suggested
SUBUNITS OF THE CBR 'Case Representation Unit 'Situation Recognition Unit 'Case Analyzer 'Case Adapter 'Case Executor 'Case Organizer
GRAPHICAL USER INTERFACE: DRAW OBJECT SELECT PASTE DRAG
GRAPHICAL USER INTERFACE: EDIT
IMPLEMENTATION: CASE LIBRARY
SIMULATION: TEST ISLAND FBlackstart: CC and ML units FNon Blackstart: LD unit
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
SIMULATION: OBJECTIVES Scenarios Faulty Components LINES E1L, C3B, Q1N and Q2N Total Blackout Target n LD Plant Restoration
SIMULATION: BLACKOUT
SIMULATION: PROPOSAL
SIMULATION: RESTORATION
ACTION CHECKING
A CASE DESCRPTION FOR SASKPOWER
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
A SOLUTION PROPOSAL
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