Optimal coordination of directional overcurrent relays in distribution systems with distributed generation based on a hybrid PSO-LP algorithm

This paper presents a new method for solving the problem of directional overcurrent relays (DOCR) coordination in distribution grids with high penetration of distributed generation (DG), using a hybrid particle swarm optimization (PSO) - linear programming (LP) algorithm. The purpose of the proposed technique is to calculate the values of pickup currents (PU) and time dial (TD) settings of each DOCR which minimize the sum of relays´ operating times subject to particular constraints. Moreover, the suggested implementation is able to handle the arising protection issues due to DG infeed and network topology changes and can be integrated into new adaptive protection schemes. Finally, the performance of the developed method will be evaluated on three test systems with varying configurations.