Optimal coordination of overcurrent relay using an enhanced discrete differential evolution algorithm in a distribution system with DG

Interconnecting a distributed generation (DG) to an existing distribution system causes an improved utilization of the local resources, prominently the renewable energy sources. Penetration of a DG into an existing distribution system has so many impacts on the system, despite the benefits a DG will provide; it has a negative impact on one of the most important aspects of the system, one of which is the power system protection. Installation of DG to the existing system will produce additional fault current which may disturb the previously coordinated relays and lead to miscoordination of overcurrent relays. In this paper, an enhanced discrete differential evolution is introduced to perform the overcurrent relay coordination required to protect the radial distribution network with distributed generators. The proposed DE generates quantized vectors and uses time varying scaling factors for enhanced operation. The case studies have been carried out to identify the effectiveness of the proposed algorithm. The results show that the optimized relay settings can improve the supply reliability especially in distributed generation cases.