Comparative Study of Relay Coordination in a Microgrid with the Determination of Common Optimal Settings Based on Different Objective Functions

This study aims to analyze the optimal settings of directional overcurrent relays (DOCRs) for protection an alternating current (AC) microgrid in both islanded and grid-connected operation modes. In this context, two different types objective functions are used comparing total operating time all primary DOCRs. The obtained either mode due variable magnitude fault currents. proposed coordination scheme is formulated as a mixed-integer non-linear programming problem, using various optimization techniques such firefly algorithm, simulated annealing genetic algorithm. results show that common modes robust no miscoordination occurs any