A Novel Protection Coordination Scheme for Regionalized Microgrid at Islanded Mode

Modern microgrids are becoming very complex due to the growing penetration levels of renewable distributed generations (RDGs). The integration of RDGs in power systems can lead to changes in fault current levels and network topologies, which in turn cause overcurrent and relay coordination issues. Design and selection of a proper protection scheme is very important for reliable and safe operation of a microgrid. In this paper, the effect of different penetration levels of renewable DGs and loads is considered for an adaptive protection coordination scheme of a regionalized microgrid. The main focus of this paper is the use of an optimization algorithm to obtain maximum current along each line, from which proper pick-up current settings can be determined for each overcurrent protection. Case studies performed across different ranges of RDG penetration and load demands show the strength of the proposed algorithm for maintaining the reliability and security of grids with high penetration of renewable generation.