Optimal coordination of overcurrent relays using a modified particle swarm optimization

In this paper, a new problem formulation is proposed to calculate the optimal relay settings of directional overcurrent relays in power systems. The proposed coordination problem is formulated as a mixed integer nonlinear problem to take into account the discrete values for the pickup current settings. A modified particle swarm optimization (PSO) algorithm is proposed to calculate the optimal relay settings. A comparison between the original particle swarm optimization based method, the proposed PSO algorithm and the GAMS solver is presented.