Moth-Flame Optimization Technique for Optimal Coordination of Directional Overcurrent Relay System

Abstract

The protection devices have an important role in modern power system. The operation of electric power system network majorly depends on combinatorial working of relays, circuit breakers and other protection devices. The power system reliability is improved majorly by installing two types of relays i.e., primary and backup relays. Initially, the primary relay operates for any faulty condition to give fast response. For any condition primary relay fails to trip, then backup relays perform same task after some time interval. The coordinated operation of primary and backup relay is important to prevent any malfunctioning due to time gap. The coordination between primary and backup relay is a nonlinear optimization problem. In this dissertation work, optimal coordination of directional over current relay is achieved using moth-flame optimization algorithm. The moth-flame optimization is population-based technique applied for calculating optimal settings of the relay with faster convergence for primary relay and better performance coordination with backup relays. Relays setting configurations includes time multiplier settings, plug settings multiplier and pickup current settings. Relay coordination is done using continuous decision variables i.e., time multiplier settings and pickup current. The technique is implemented on IEEE 8-bus test system without external grid and results are compared to other techniques results.