A Protection Scheme for Microgrids Based on Active Power Variation Coefficient

Due to the characteristics of bidirectional power flow and smaller fault currents, traditional relay protection schemes are difficult to apply to microgrids. In this paper, a microgrid protection scheme based on the active power variation coefficient of the zone is proposed. Firstly, the impedance angle variation characteristic on the zone bus during the internal and external faults is analyzed. Then, the protection criterion is formed based on the difference between the active power variation coefficient in the internal fault and the external fault. Finally, a typical microgrid simulation model was built in MATLAB/SIMULINK to verify the proposed scheme. The results show that the protection scheme can effectively distinguish internal and external faults and realize fault detection and location.