光伏电站经柔性直流集电送出系统的低电压穿越协调控制策略

摘要

Large-scale PV stations integrated with VSC-HVDC should equip with the fault ride-through capability when the AC grid trips.A novel coordinated low voltage ride-through control strategy is proposed between VSC-HVDC and PV stations,which does not rely on communications and can maintain the balance of active power transmission quickly.In case of grid fault,the control modes of HVDC converters can be switched according to the DC voltage variation level.The sending end converter can lower down its output voltage,which will cause the PV stations decrease their output power.Hence the proposed method can stabilize the DC voltage and improve the fault ride through capability of the whole system even when the AC fault occurs in the sending grid.Simulation model with 1000 MW PV stations and VSC-HVDC is developed in Matlab/Simulink to prove the validity of the proposed control strategy.%光伏电站经柔性直流集电送出系统在交流电网发生故障扰动时应该具备低电压穿越的能力.针对受端和送端交流电网发生故障扰动的情况,提出了一种不依靠通信的光伏电站与VSC-HVDC的低电压穿越协调控制策略.交流电网故障情况下,VSC-HVDC送、受端换流器可依据直流电压的变化量切换控制模式.送端换流器根据VSC-HVDC直流电压的变化量调节光伏电站出口的电压幅值,使光伏电站感受到电压变化并减小有功功率输出,从而迅速维持VSC-HVDC系统的功率传输平衡,提升系统故障穿越能力,而且可以实现直流电压的稳态无差控制.应用Matlab/Simulink仿真软件搭建了1000MW光伏电站与VSC-HVDC系统的仿真模型,验证了所提协调控制策略的有效性.