基于超级电容蓄能的永磁同步海上风电低电压穿越研究

摘要

为避免电网电压跌落导致海上风电机组脱网运行,分析了直驱永磁同步海上风电系统的双PWM全功率变流器控制策略,提出了一种基于超级电容器蓄能的海上风电机组并网运行低电压穿越方案.在双向变流器的直流侧并联超级电容蓄能系统,利用超级电容来维持电网故障时的功率平衡,稳定直流侧母线电压.利用网侧变流器静止无功补偿运行模式控制无功电流输出,向电网提供无功功率支持.仿真结果表明了该方案在电网故障时,能有效抑制直流侧过电压,向电网提供无功功率,有利于电网故障恢复,提高了直驱永磁海上风电系统的低电压穿越能力.%In order to avoid offshore wind turbine off grid operation caused by grid voltage sag, the control strategy of dual PWM full power converter for direct drive permanent magnet synchronous with offshore wind power system is analyzed, a scheme of Low Voltage Ride Through (LVRT) for offshore wind turbines during grid-connected operation is presented based on Super-Capacitor Energy Storage System (SC_ESS). By paralleling super-capacitor energy storage system on the DC side of the bidirectional converter, this paper uses the super capacitor to stabilize the power balance during the grid fault and ensure the stability of the DC side voltage; it adopts static var compensation operation mode of grid-side converter to prior output reactive current and provide reactive power support to the grid. Simulation results show that under system fault, the presented scheme can efficiently restrain the DC side overvoltage, provide reactive power to the power system, speed up the restoration of power grid fault, and improve the LVRT capability of the offshore wind power system.