Bereket Demissie2026-03-092024-10-19https://etd.hu.edu.et/handle/123456789/1207Coordination of protective device in power distribution system has vital importance for the smooth operation of power system in term of selectivity, avoiding mal-operation of protective relays thereby minimizing unnecessary power loss. Yirgalem distribution system contains several problems in term of its primary and secondary protection schemes. This includes short circuits, overloading and overlapping. Since protective devices in Yirgalem distribution system is missing proper coordination, there is unnecessary tripping, removal of healthy part of system, equipment damage due to protective relays are not sensing fault and power loss occurs. Therefore, to reduce such kind of problems, some mitigation methods are needed to be implemented. These are selecting proper setting of relays, selection of appropriate overcurrent protective device, optimal coordination of protective devices. This thesis presents optimal coordination of protective devices for Yirgalem distribution system by minimizing the operating time of relays in primary as well as back up protection. In this research we have utilized Electrical Transient Analyzer Program (ETAP) software to coordinate protective devices and observed that protective devices get coordinated but it missed the objective of the thesis that is, minimizing the operating time of relays. Therefore, to obtain the minimum operating time of relay we have used Nature-based algorithm called Antlion Optimization techniques and particle swarm optimization (PSO) techniques. Power system in distribution area mostly comprises of protection devices like fuse, circuit breakers, re closers and protective relays. For the sake of optimal operation of these devices, system design engineer should take care of weather the devices are operating in coordinated manner or not. Optimization is the process of obtaining optimal solution (minimum or maximum) from the set of possible solutions (a given search space). Therefore, based on Ant Lion optimization technique and particle swarm optimization (PSO), the distribution system protection system is coordinated and minimum operating time of relay is obtained for respective feeders at Yirgalem distribution system. Antlion optimization(ALO) is better since the obtained minimum operating time of relay by it is more less than that obtained from Particle swarm optimization (PSOenAnt Lion Optimization (ALO)Particle swarm optimization (PSO)Electric Transient Analyzer Program (ETAP) Protective devicesProtective device coordinationSelectivityThesis