Mixed Integer Optimization of IDMT Overcurrent Relays in the Presence of Wind Energy Farms Using PSO Algorithm

Abstract

This paper presents an optimal coordination of inverse definite minimum time (IDMT) directional overcurrent relays (DOCR) in the presence of Wind Energy Farms (WEF). Firstly, the impact of WEF on the relays coordination is focused, after that we search for the new relays setting to ensure an optimal coordination of the relays. The coordination problem is formulated as a constrained nonlinear mono-objective optimization problem. The objective function of this optimization problem is the minimization of the operation time of the associated relays. In terms of decision variables; two types of optimizations are considered in this paper, namely: real parameter optimization where, the time dial setting (TDS), and the pickup current setting (IP) are considered as the real decision variables of the optimization problem and the mixed integer optimization, where the IEC curve characteristic of each relay is added to the previous variables as an integer decision variable. The characteristics of the relays are always chosen arbitrary or by trial and error method. To solve this constrained non linear optimization problem, the particle swarm optimization method is used. The proposed method is validated on IEEE 8-bus power transmission test systems considering various scenarios.