EXPERT SYSTEM FOR A CONTINGENCY HANDLING OPERATION

Abstract

Power systems are often subject to supply interruptions and disturbances. Operating under a highly constrained environment, they can pose a serious threat to for system security. Correct, timely detection and diagnosis of these outages, called as " contingency handling operations " is a. very significant problem in electric power industry. The outage of a. line or generator produces single or multiple contingencies which require the modification of operating conditions. These modifications include change of transmission line loading and generation. Multiple contingencies produce more significant problems which can be solved by rearranging the system. This requires the experts' knowledge. The project aims at developing an expert system to aid operators in case of single or multiple transmission line or generator outages. Outage studies have been conducted for certain credible cases and their results analysed and presented. In addition, corrective procedures required to maintain system security ha.ve also been clearly spelt out. In extreme cases of multiple level contingencies, analytical studies fail to present a solution and hence human expertise plays a crucial role in handling such contingencies. Expert engineers use their familiarity and experience with the system in order to come with a heuristic method of recovery. But even then handling a multiple contingency could be time consuming and most importantly, the unavailability of an expert when needed. Therefore this system tries to overcome this obstacle by extracting and capturing the knowledge of expert engineers and combining it with the results of analytical studies into a knowledge based system in which the heuristic approach of the experts are coded as rules and conditions. Consequently this expert system will advice the operator on the course of action to be taken in the event of the occurrence of such contingency. It educates him by explaining the underlying logic and reason behind every decision made in arriving at a solution. This system is developed in PDSS MProlog and implemented on the SUN Microsystems workstation. The loadflow program is written in Fortran using Newton-Raphson technique and was successfully interfaced with the Prolog program via an external C-Shell Script file. It has been operated on test systems such as IEEE6 and IEEE30 bus systems and a large scale 131 bus practical system, the Singapore transmission line network. Case studies have been presented for all three systems which clearly demonstrates its competence in handling system contingencies.