Adaptive Droop Control Strategy for Offshore Wind Power Through VSC-HVDC System Considering DC Voltage Limitation

In order to realize the reasonable distribution of the disturbance power of the offshore wind power through the VSC-HVDC system between different sending-end converter stations, this paper proposes an adaptive droop control strategy for the converter station of offshore wind power VSC-HVDC transmission system considering DC voltage stability. Firstly, the complete transmission mechanism of the power disturbance signal of the offshore wind power through the VSC-HVDC system is established. Through the droop relationship between the DC voltage and the frequency of the island system, the DC voltage fluctuation caused by the power disturbance of the receiving power grid is converted into the frequency fluctuation of the island system. The offshore wind farm adjusts its own active output by sensing the frequency change, and realizes the active support without communication to the receiving power grid. Furthermore, the sending-end converter station adaptively adjusts the droop coefficient in real time by detecting the wind power output margin and DC voltage deviation, reasonably distributes the disturbance power of the receiving-end grid, and reduces the fluctuation of DC voltage. Finally, in PowerFactory / Digsilnet, the simulation analysis is carried out based on the four-terminal VSC-MTDC system to verify the effectiveness and superiority of the proposed control strategy.