Optimal over Current Relay Coordination of IEEE 9 Bus System using Mipower

Abstract

The protective system plays a major role which has great effect on the power system operation. The modern interconnected power system consists of large numbers of protective relays and circuit breakers which constitute an integral part of the protective scheme. The main function of the relay is to sense and locate the fault and sends a command to the breaker to isolate the faulty element. The objective of the relay coordination is to provide primary as well as backup protection from any fault that is likely to occur in the power system. In this paper, overcurrent relay coordination is implemented on an IEEE 9 Bus test system using MiPower software for phase and earth faults. The Load flow analysis and the short circuit analysis on the IEEE 9 Bus test system is initially done followed by relay coordination. Fault MVA and Fault current data obtained from short circuit analysis enables us to obtain operating time of the relays used in the test system. The calculated value of operating time gives the coordinated operation of all the relays. The MiPower software has unique feature which is very useful in proper coordination of overcurrent relays.