A Calculation Method of Asymmetric Faults Current in Three-Phase Four-Wire Synchronverter

Three-phase four-wire virtual synchronous generator (TPFW-VSG) provides a zero-sequence current path by introducing a neutral line. However, it will generate an inrush current under asymmetric faults, which will damage the power electronic devices. Therefore, it is of great value to analyze TPFW-VSG's fault current characteristics. In this paper, the calculation method of instantaneous inrush current of TPFW-VSG under asymmetric faults is proposed by simplifying equivalent models, and the main influencing factors of asymmetric faults current are analyzed. The analysis shows that the fault current is mainly composed of the periodic component and the free component. Moreover, the main influencing factors include control loop and asymmetric faults type. Finally, PSCAD simulation and MATLAB calculation results verify the correctness of the above analysis.