Power System Restoration with Power System Restoration with the Help of a Case-Based the Help of a Case-Based

Expert SystemExpert System

N. Chowdhury Power Systems Research Group

University of SaskatchewanSaskatoon, Canada

INTRODUCTIONBlackouts

Rare in a modern power systemCause huge financial losses

System OperatorsDo not gain enough working knowledge and experience on restorationShould be trained to restore their systems

INTRODUCTIONINTRODUCTION 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 Graphical User

CBR Subsystem Action Checker

Interface

OBJECT-ORIENTED GUI

CASE-BASED REASONING SUBSYSTEM

Library Retriever

Ranking Modification

Ranked Case Case

Case Match/ Case

Cases Adaptor

Solution

Case

SituationNew

Plan

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:GRAPHICAL USER INTERFACE: DRAWDRAW

OBJECT

SELECT

PASTE

DRAG

GRAPHICAL USER INTERFACE:GRAPHICAL USER INTERFACE: EDITEDIT

IMPLEMENTATION:IMPLEMENTATION: CASE LIBRARYCASE LIBRARY

SIMULATION:SIMULATION: TEST ISLANDTEST ISLAND

Blackstart: CC and ML units Non Blackstart: LD unit

SIMULATION:SIMULATION: STRATEGYSTRATEGY

Path Selection Restoration Power Source Number of Switching Actions

Test Island CASE 1: CC - ER - LD CASE 2: CC - BR - NB - LD CASE 3: CC - QE - NB - LD CASE 4: QE - NB - LD CASE 5: QE - CC - ER - LD

SIMULATION:SIMULATION: OBJECTIVESOBJECTIVES

Scenarios Faulty Components

LINES E1L, C3B, Q1N and Q2N

Total Blackout

Target LD Plant Restoration

SIMULATION:SIMULATION: BLACKOUTBLACKOUT

SIMULATION:SIMULATION: PROPOSALPROPOSAL

SIMULATION:SIMULATION: RESTORATIONRESTORATION

ACTION CHECKINGACTION 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