Coordination of distance and directional overcurrent relays using a new algorithm: grey wolf optimizer

Abstract

Optimal relay coordination has important effects on the stability, security, and reliability of a network. Hence,in this article, a method for optimal coordination of distance (D) and directional overcurrent (DOC) relays is presented.Taking into account the pickup current of the overcurrent relays as an optimization variable, in addition to the timesetting multiplier (T SM ) and the various characteristics of these relays, optimum and suitable settings for overcurrentand distance relays are obtained. The grey wolf optimizer algorithm has been used as an optimization tool to findoptimum settings. The performance of this method has been investigated in 8-bus and 39-bus systems and comparedwith traditional GA and PSO algorithms. The results show that in the proposed method the operating times of therelays and the time interval between operating times of main and backup relays with respect to the coordination timeinterval have decreased