Control Strategy of Voltage Active Support and Fault Current Suppression in AC System of MMC

The application of fully controlled insulated gate bipolar transistors as commutation devices and the voltage source converters constituted by them in power systems has produced and promoted the development of flexible direct current transmission technology. Considering the fragility of power electronic devices, if a short-circuit fault occurs in the HVDC system, the resulting overcurrent may damage the power electronic devices. This paper proposes a control strategy for flexible DC operation, which can realize active support for AC voltage and suppress fault short-circuit current. Finally, a simulation verification platform is built based on PSCAD/EMTDC. The simulation results show that the control method proposed in this paper can effectively achieve the expected control objectives and ensure the stable operation of the system.