弱电网下双馈风电机组电网电压扰动补偿控制策略

针对弱电网下双馈风电并网系统的稳定性问题,文中提出了一种基于电网电压扰动补偿的双馈风电机组补偿控制策略。首先,在同步旋转坐标系下建立双馈风电机组,包括转子侧变换器和网侧变换器的统一阻抗模型。然后,基于所建立的阻抗模型分析了并网点电压扰动到控制器输出的传递关系,分别在转子侧电流环和网侧电流环引入了电压扰动补偿对变换器进行改进控制,并通过广义奈奎斯特判据证明了该方法能有效提高双馈风电机组在弱电网下的并网稳定性。理论分析表明,基于并网点电压扰动补偿的转子侧和网侧补偿控制能很好地改善双馈风电机组的输出阻抗特性,从而提高其在弱电网下的稳定性。最后,通过仿真分析验证了该补偿控制方法的有效性。

Control Strategy of Disturbance Compensation for Grid Voltage of DFIG Based Wind Turbine in Weak Grid

A compensation control strategy for doubly-fed induction generator (DFIG) based wind turbine is proposed based on disturbance compensation of grid voltage, which can solve the stability problem of grid-connected in weak grid. Firstly, a unified impedance model of DFIG based wind turbine is established in the synchronous reference frame including rotor side converter (RSC) and grid side converter (GSC). Then, based on the established impedance model, the transfer relationship between the voltage disturbance at point of common coupling and the controller output is analyzed, the voltage disturbance compensation is introduced into the current loop of RSC and GSC respectively to improve the converter control. The generalized Nyquist criterion (GNC) proves that the proposed method can effectively improve the grid-connected stability of DFIG based wind turbine in weak grid. Theoretical analysis shows that the compensation control of RSC and GSC based on the voltage disturbance compensation at point of common coupling can improve the impedance characteristics of DFIG so as to improve their stability under weak grid condition. Finally, the effectiveness of the proposed compensation control method is verified by simulation analysis.