Optimal coordination of directional overcurrent relays using harmony search algorithm

Directional over current relays (DOR) are used to protection of interconnected networks and looped distribution systems. Several techniques and formulations have been proposed to solve the optimal coordination of DOR problem. In this paper, harmony search algorithm (HSA) is proposed for optimal coordination of DOR in a looped distribution system. Then this algorithm is developed to a new Improvised harmony search algorithm (IHSA) to solve the same problem. IHSA employs a new method that enhance fine tuning and convergence rate of HSA. The optimal setting of over current relays for a standard distribution network are obtained and comparison between the new methods and some other methods is made.