Optimum Coordination of Directional Overcurrent Relay using Genetic Algorithm Technique

This paper presents genetic algorithm (GA) method for coordination of overcurrent (OC) relays for the protection of ring connected system from sudden built up of current occurring due to shunt faults. Overcurrent relays preeminently IDMT (Inverse Definite Minimum Time) relays are preferably used and are major protective device in the distribution system, these OC relay are usually operating as backup protection, but incase it could be the only protection provided. The OC relay coordination is a highly confined optimization problem, the intent is to find an optimum relay setting, so as to curtail the time of operation of relays and at the same instant to elude the malfunctioning of relays and hence, OC relay coordination in power distribution network is a major concern. The optimum coordination of OC relays can be obtained by different algorithm techniques for a mesh connected distribution system, here GA technique is used. For excellent conditions of selectivity and coordination of OC relays, by selecting the optimum values of time multiplier setting (TMS) and plug setting (PS) of OCRs for improving the feeder reliability indices in power distribution networks. In this paper, a case of 9 bus mesh system is considered, and optimum coordination is obtained using GA method.