Research on Microgrid Relay Protection Scheme

The access of the distributed power source makes the microgrid have the characteristics of complex topology and two-way flow of the power flow, and the fault output current of the power electronic interface power supply is different from the traditional synchronous power supply, which makes it difficult for the conventional distribution network relay protection to operate reliably and quickly. In this paper, the equivalent output model of different types of power supplies in microgrid under normal operation and fault conditions is analyzed. According to the difference of electrical quantity characteristics before and after the fault, a microgrid relay protection scheme including multiple principles is formed, which can occur in different lines. It has a good practicability to accurately determine the occurrence of faults and identify faults inside and outside the line segment when different types of faults occur. Finally, the effectiveness of the proposed method is verified by PSCAD/EMTDC simulation.