Research on the direct current control method and simulation of flexible HVDC

Flexible HVDC technology has got widespread concern in the world and has a broad application space in the fields of large capacity clean energy connecting and power grids interconnection. In this paper, the application status and technical advantages of flexible HVDC technology were summarized, the system structure and control strategy of flexible HVDC were studied. The direct current control methods for two-terminal flexible HVDC in different application occasions were mainly researched. In general situations, converter A uses constant DC voltage control mode and reactive power compensation control mode. Converter B uses constant active power control mode and reactive power compensation control mode. When supplying for passive network, converter A uses constant DC voltage control mode and reactive power compensation control mode. The reference voltage value of DC bus should be set higher than general situations. Converter B uses constant AC voltage control mode. The specific control principles were analyzed, and the simulation models were established. Simulation results verified the correctness of the control method.