Optimum coordination of overcurrent relays in distribution system using genetic algorithm

This paper presents genetic algorithm (GA) method for coordination of overcurrent (OC) relays. The OC relays are the major protection devices in a distribution system. OC relay is usually employed as backup protection. But in some situations it may be the only protection provided. To reduce the power outages, mal-operation of the backup relays should be avoided, and therefore, OC relay coordination in power distribution network is a major concern of protection engineer. The OC relay coordination in ring fed distribution networks is a highly constrained optimization problem. The purpose is to find an optimum relay setting to minimize the time of operation of relays and at the same time, to avoid the mal-operation of relays. This paper presents GA technique for optimum coordination of OC relays in a ring fed distribution system. Constraints are incorporated in the fitness function making use of the penalty method. Computer programs (using MATLAB) have been developed for optimum coordination of OC relays using GA technique.