Small Signal Modeling and Decoupling Control of VSC-MTDC

In this paper, VSC-MTDC(Voltage Source Converter based Multi-Terminal Direct Current) is taken as the research object. Based on the small signal model, the coupling mechanism between the converter stations and the AC / DC side of the converter station in the VSC-MTDC is revealed, and the decoupling control strategy is studied to weaken the interaction between the converter stations. Firstly, the small signal model of VSC-MTDC is constructed from three parts: AC network, controller and DC network. Based on the small signal analysis method, the coupling mechanism of VSC-MTDC is revealed, and then a local DC voltage feedback decoupling control strategy is proposed to restrain the coupling between converter stations. The simulation results show that the decoupling control strategy can effectively reduce the mutual interference between converter stations and improve the stability of the whole system.