Conventional Protection Approach for Microgrids Considering all types of Phase faults for both Grid Connected and Islanded Mode

Microgrids, now a days are attracting the Power system designer’s interest as they have capability to provide power in island mode by disconnecting from utility grid in case if any major fault occurs to utility. Fossil fuels utilization for power generation is harmful for environment while Microgrids are echo friendly as they encourage the use of Renewable Energy. During the planning of a Microgrids, the Protection design is major concern for their reliable operation. Due to presence of Distributed Energy Resources inside Microgrids the current flow direction doesn’t remain conventional (from utility to load), hence an intelligent protection scheme is required. After the transition from grid connected to island mode the fault currents magnitude drastically changes which affects the protection because the over current relays inside microgrid are set on high pickup current values. In this paper a robust low cost and efficient current controlled undervoltage protection scheme is introduced which use locally measured current and voltage and make tripping decision to ensure the protection under island as well as Grid-connected mode and don’t require any communication channel. This protection scheme is tested on 9-Bus Canadian Urban Benchmark Distribution System developed on ETAP Software.