Solving Optimal Coordination of Direction Overcurrent Relays Problem Using Grey Wolf Optimization (GWO) Algorithm

The optimal coordination of DOCRs becomes a very hard task as the power system becomes complex and larger. In this paper, the recent GWO technique is proposed to find the optimal settings for directional overcurrent relays (DOCR), minimize the total operation time for all primary relays, and maintain the relay coordination margin between relay pairs using GWO. The relay settings, pick up current (Ip) and time dial setting (TDS), are considered as decision variables. The operating time of a relay depends on these variables. The availability of the suggested technique is tested using fifteen bus network system using MATLAB. The results using GWO algorithm are compared with electromagnetic field optimization (EMF), Cuckoo Search Algorithm (CSA), and modified electromagnetic field optimization (MEFO). The results using GWO prove the viability of the proposed algorithms for solving DOCRs coordination problem compare with other optimization algorithms.

I. Introduction

One of the most complex systems that have been built by human civilization is the power system. The power grid system is growing larger and larger, and the complexity of power system operation also increasing [1], [2]. The important task for the protection relays is to identify and isolate faults quickly [3]. DOCRs are used in the protection of power distribution networks. Maintained the validity of the sequential operation between relays and o find suitable settings for the protective relays are the main objectives. In another word, backup relays should work after a time margin in case of primary relays fail to operate [4].