Mitigating low fault current in microgrids through renewables-battery hybrid units

•An effective protection scheme for mitigating low fault current in microgrids during an islanded mode of operation.•An adaptive protection scheme that considers renewable energy resources, Battery Energy Storage System (BESS), hybrid units in microgrids.•An internal cooperation strategy between renewable energy resources and battery energy storage system to ensure reliable output power of energy sources.•A novel fault current zone formation that is based on the combination of power flow and fault current analysis.•An optimal residual capacity is determined for the BESS units to compensate for low fault current.