Optimized settings of directional overcurrent relays in meshed power networks using stochastic fractal search algorithm

Abstract

Summary This paper presents a novel application of the stochastic fractal search algorithm to solve the optimal relay coordination problem of meshed power networks. The optimization problem has 3 design variables, which are the time dial, the pickup current, and the tripping characteristic of each relay and subjects to set of coordination constraints. The objective function is adapted to minimize the total operating time of the primary and backup relays while maintaining the validity of coordination within acceptable limits. Three interconnected power systems with various topologies and fault scenarios are demonstrated. Among these 3 test cases, it is worthy emphasizing that the third power system is highly penetrated with 6 distributed generators, which tangle the optimization problems with numerous relay pair scenarios. The validity and the effectiveness of the proposed method are confirmed using the simulation results, in addition to necessary subsequent comparisons to other competing approaches. The simulated numerical results and the performance measures indicate that the stochastic fractal search algorithm is viable and able to generate competitive optimal settings for overcurrent relays and lie in an acceptable elapsed time.