Dual Setting Directional Overcurrent Protection Coordination for Microgrids Considering Single Outage Contingency

Distributed generation units (DGs) are essential components in microgrids (MGs) and modern distribution systems considering their important advantages. But, their presence in microgrids results in complicated protection coordination problems. This paper suggests a protection coordination scheme (PCS) in MGs, which is based on dual setting directional overcurrent relays (DOCRs) considering single outage contingency. In this paper, the conventional and dual setting DOCR-based PCSs are compared in two steps, without and with considering the single outage contingency, respectively. It is shown that in complex and practical cases, the advantages of the dual setting based PCS is more obvious. To reveal the validity of the proposed PCS, the simulation studies are conducted based on the modified version of the IEEE 30-bus test system. Using the short circuit currents obtained by DIgSILENT, the optimization problem is solved in MATLAB environment as a mixed integer non-linear programming problem. The results show the superiority of the Dual setting PCS over the conventional PCS.