电网电压跌落下双馈风力发电系统强励控制

为增强电网故障下双馈风力发电系统(DFIG)的低电压穿越(LVRT)运行能力，提出一种DFIG转子侧变换器(RSC)强励控制策略。在基于定子磁链定向的矢量控制策略中增加多频比例谐振控制器(MFPR)，当电网故障造成发电机定子电压跌落时，多频比例谐振控制器能够对转子侧变换器(RSC)的输出励磁电压进行补偿，抑制转子故障电流，实现DFIG的低电压穿越运行。分析了转子电压等级与DFIG的低电压穿越运行区间的关系，为DFIG转子侧变换器的电压等级设计标准提供了参考依据。控制系统结构简单，保证了系统的响应速度，可同时对电网对称跌落和不对称跌落产生的故障电流进行抑制。通过对1.5 MW双馈风力发电机组进行仿真研究，验证了理论分析的正确性和所提控制策略的可行性。

Forced excitation control of wind power system with DFIG during grid voltage dips

In order to enhance low-voltage ride through (LVRT) ability of wind power system with doubly-fed induction generator (DFIG) under grid faults, a forced excitation control strategy for DFIG rotor side converter (RSC) is proposed. A forced excitation multi-frequency proportional resonant (MFPR) controller is added to stator flux vector based control strategy. In case of stator voltage dips caused by grid faults, forced excitation resonant controller is able to compensate output voltage of the rotor side converter. Fault current in the rotor is suppressed and LVRT for DFIG is realized. Also, the relationship between rotor voltage class and LVRT region of DFIG is analyzed, providing design reference of voltage class for DFIG rotor side converter. The control system is simple and has fast response. It can be used to suppress fault current induced by symmetric and asymmetric voltage dips. Simulations on 1.5 MW wind power system are performed to verify the correctness of theoretical analysis and the feasibility of the proposed control strategy.