Effect of fault location on optimal coordination of directional over current relay

The objective of optimal relay coordination in interconnected power system is to achieve selectivity without sacrificing sensitivity & fast fault clearance time. This paper presents the effect of fault location on the flow of current direction & optimal coordination of directional over current relay. In this coordination problem Time Dial Setting (TDS) & Pick up Current Setting (Ip) of all relays considered as optimal parameter & it will provide coordination for all kind of fault (LLL, LLG, LG). The problem is solved using optimization toolbox of MatLab for continuous value of TDS & Ip.