A hypothesis of VSC-HVDC ring-network and its control strategy for china's power grid

The reverse distribution of energy, as well as the requirement for utilizing renewable power, determines the pattern of the long-distance and bulk power delivery in China, which brings about new problems in power systems. This paper addresses on this issue and proposes a six-terminal voltage source converter based high voltage direct current (VSC-HVDC) ring-network for China's power grid. A coordinate control strategy consists of droop controls and an additional control for restraining wind power fluctuation cross-regionally among the ring-network is presented, which is well applicable to China's power grid. The hydro power with fast adjusting speed and sufficient peak load regulating capacity can be effectively used to minimize the frequency deviation caused by wind fluctuation. The technical feasibility is validated by simulation cases on realtime digital simulator (RTDS), based on the planning data and load demands of Year 2020 for China's power grid. Simulation results show that the six-terminal VSC-HVDC ring-network with the proposed control method is of great potential and feasibility.