Optimal directional relay placement in microgrids considering coordination constraints

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This paper is concerned with the optimal placement of protection devices in a microgrid (MG) using genetic algorithms. The occurrence of power outages in distribution networks is higher than that of other parts of the grid. This phenomenon may impose substantial damage on customers with sensitive loads. The new concepts of distributed generation (DG) and microgrid (MG) in modern distribution systems can reduce the number of outages and associated damages by supplying a feeder from multiple sources. However, microgrids and distribution networks with DG require significant effort for the coordination of DGs and their protection devices. Therefore, the placement of protective equipment in order to limit the scope of the fault is one of the important issues which power engineers face. Adding DGs to a distribution system creates different sets of operating conditions such as reverse power flow and increased fault levels. In this paper, using the graph theory, various branches of a feeder are identified and the constraints for using genetic algorithm to optimize the location of protective equipment are derived. In the proposed algorithm, the location, type and direction of relays are optimized simultaneously. The results of implementing the proposed approach on a 33-bus test network confirm the performance and accuracy of this method.