Optimal Over-Current Relay Coordination Using Improved Harmony Search Method.

This paper presents optimal coordination of over-current relays by using improved harmony search method (IHS). The objective function of the relay coordination problem is to minimize the operation time of associated relays for given fault conditions in the protection system. The control variables used in this paper are the pickup current and the time dial setting of the relays. The proposed method was tested with 5-bus, WSCC 9-bus and standard IEEE 14-bus test systems. For benchmarking, sequential quadratic programming (SQP) and genetic algorithm (GA) were employed to solve this optimal relay coordination problem. The results showed that the IHS is capable to minimize the operation time of relays in the entire system. As a result, all search algorithms can solve optimal coordination relay which the improved harmony search method gives the best solutions for optimal coordination relay setting. [ABSTRACT FROM AUTHOR]