The main protection challenges in the microgrid are the bi-directional power flow, protection blinding, sympathetic tripping, change in short-circuit level due to different modes of operation, and limited fault current contribution by converter-interfaced sources. Microgrids help leverage these DERs to keep the power on when the normal supply is unavailable (e., due to faults or equipment outages). These systems, however, present unique protection challenges to detect and respond to faults. This report describes some challenges and potential solutions for. The design of both systems must consider the system topology, what generation and/or storage resources can be connected, and microgrid operational states (including grid-connected, islanded, and transitions between the two). This report was prepared as an account of work sponsored by an agency of the United States Government. 22 of CIGRE defines microgrids as “electricity distribution systems containing loads and distributed energy resources (such as distributed generators, storage devices, or controllable loads), that can be operated in a controlled, coordinated way either while connected to the main power. A microgrid is a local network including renewable and non-renewable energy sources as well as distributed loads.
