Analysis of An Abnormal Overcurrent Phenomenon of Fault Ride-Through of Virtual Synchronous Generator

Fault ride-through (FRT) prevents the virtual synchronous generator (VSG) from being burnt by the fault current. Mode switching control (MSC) is one of the most classic FRT control strategies for VSGs. However, a new abnormal overcurrent phenomenon of the VSG which uses an existing MSC is discovered in this paper. Firstly, the overcurrent phenomenon is presented. Then, characteristics of the output current of the VSG which uses different parameters are compared and analyzed. Then, an improved MSC is proposed based on the above analysis. Finally, a simulation based on the PSCAD/EMTDC is proposed to verify the effectiveness of the proposed method. The problem is described that the abnormal overcurrent occurs on the grid-connected inverter which uses traditional MSC under nonideal grid frequency. The effectiveness of the proposed method for solving this problem is verified.