Method and system for suppressing asymmetric fault current of GFM-VSC grid-connected system

The invention provides a method and system for suppressing asymmetric fault current of a GFM-VSC grid-connected system, and the method comprises the steps: carrying out the phase shift of the port voltage and internal potential of each phase in the GFM-VSC system, building a virtual coordinate system, and generating a virtual port voltage and a virtual internal potential; judging the relative position of the virtual internal potential of each phase of the GFM-VSC system and the virtual port voltage under the large disturbance in a split-phase manner to determine whether to compensate or not, calculating the amplitude-phase compensation value of the internal potential of each phase, and changing the internal potential of each phase of the GFM-VSM system based on the amplitude-phase compensation value of the internal potential of each phase. Therefore, it is ensured that the system current always meets the maximum current constraint allowed by the equipment, and then fault current suppression of the GFM-VSC sys