Optimal Coordination of Protective Devices for Power Distribution System using Teaching Learning Based Optimization (Case Study: Dilla Power Distribution System)

Abstract

A protective device coordination study can maximize power system selectivity, avoid mal operation of the relay and remove unnecessary power loss in the power system protection. In Dilla power distribution system, various problems arise in the primary and secondary protection systems. These are overloading, overlapping and short circuit problems. In this case, the overcurrent relay cannot sense such fault which causes protective devices to miss coordination and sympathetic tripping. To reduce such problems, proper setting and selection of protective devices have to be done on the existing distribution system. This thesis presents optimal coordination of protective devices for Dilla power distribution system through minimizing the total operating time of relays in the primary and secondary protection systems. To minimize the total operating time of the relay, existing and optimized system results have been compared. Before optimization, the total operating time of the relay in the primary and secondary protection system has been determined using Electrical Transient Analyser Program (ETAP). Then after optimization, the total operating time of the relay in the primary and secondary protection system has been determined using Teach Learning Based Optimization (TLBO) algorithm and Particle Swarm Optimization (PSO) algorithm. Thus, the total operating time of the relay in the primary and secondary protection systems have been minimized by 89% and 89.3% respectively using TLBO. Similarly, the total operating time of the relay in the primary and secondary protection system has been minimized by 87.7% and 87.39% respectively using PSO. It is seen that the performance of both algorithms are suitable, but TLBO gives better results of minimizing the total operating time of the relay in primary and secondary protection system