基于电流协同优化的柔直输电系统受端换流站故障穿越控制方法OA

When an AC fault occurs at the receiving-end grid of modular multilevel converter based high voltage direct current(MMC-HVDC),it should have fault ride-through(FRT)capability.However,no FRT standards have been established for MMC-HVDC yet.Existing studies mostly reference the national standards for integrating onshore wind farms into power system,which involve proportionally generating reactive current to elevate the point of common coupling(PCC)voltage at the receiving-end converter station,reducing the active power output.When a high level of active power is injected into the sending-end converter station,active power accumulation results in significant DC overvoltage in MMC-HVDC systems.To address this issue,this paper derives an analytical expression for the active power output and reactive current of receiving-end converter.On this basis,a receiving-end FRT control method for MMC-HVDC is proposed,based on current coordinated optimization.This approach minimizes active power accumulation by balancing and adjusting the ratio of reactive and active current,while ensuring voltage safety at the PCC.Simulation results show that compared with existing projects,the proposed method greatly reduces the rate of DC voltage rise during the initial stage of a fault-by up to 100％-enhancing the FRT capability of the MMC-HVDC receiving-end converter station.