Sensitivity analysis on inverse characteristics of directional over current relays using differential evolution algorithm

Abstract

Protection relays in a power system makeup to pairs, one as main protection relay and the other as a backup protection relay. Directional over current relays (DOCR) have been using for backup protection mainly in distribution system. Coordination of these DOCRs is an optimization problem that is being solved using various types of optimizing algorithms by the researchers in the field. This paper attempts this problem in different direction which analyzes different inverse characteristics of DOCR and their sensitivities to different faults. Optimal values for time dial and plug settings for the DOCRs are obtained by using a recently developed algorithm: Opposition based chaotic differential evolution algorithms. IEEE 4-bus system has been taken as a test model and the algorithms are implemented in it for different types of characteristics based on the degree of inversion i.e., normally inverse, very inverse, extremely inverse and long-time inverse characteristics. © 2014, The Society for Reliability Engineering, Quality and Operations Management (SREQOM), India and The Division of Operation and Maintenance, Lulea University of Technology, Sweden.