Grid requires that wind farm or wind turbine should have low voltage ride-through capability, which includes that wind farm should provide reactive power support during grid fault. However, in order to achieve self-protection of the rotor-side converter of DFIG, Crowbar will be triggered, which leads to lose the ability to control power. For this issue, a mathematical model of grid-side converter (GSC) is established and the basic principle of STATCOM is analyzed, then a reactive power support strategy is proposed in this paper. The power support strategy means that both STATCOM and the grid-side converter provide reactive support to the grid during grid voltage dips and support grid voltage recovery. Simulation analysis is achieved in the Matlab/Simulink. Simulation results show that the reactive support strategy can effectively support grid voltage recovery and improve the low voltage ride through capability of wind power system based on DFIG.%电网要求风电场/风电机组具有低电压穿越能力,其中包括风电场在电网故障期间应该提供无功支持,但是双馈风机转子侧变流器（RSC）为了实现自我保护会触发Crowbar而被旁路,失去对风机的功率控制。针对这个问题,建立了风机网侧变流器（GSC）的数学模型,分析了STATCOM的基本原理;提出一种无功支持策略,即电网电压跌落期间STATCOM与风机网侧变流器共同向电网提供无功功率,支持电网电压恢复。基于Matlab/Simulink平台进行仿真验证,结果表明,该无功支持策略能有效支持电网电压恢复,提高双馈风电系统的低电压穿越能力。
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