弱电网情况下双馈风电机组改进虚拟感抗控制方法

当前弱电网条件下双馈风电机组的运行稳定性问题受到广泛关注。在同步旋转坐标系下建立了综合考虑锁相环、转子侧电流环和功率环控制器影响的双馈风电机组等效输入导纳模型。在此基础上,结合广义奈奎斯特稳定判据分析了增大转子侧电感对系统稳定性的提升作用,由此提出在控制器中引入虚拟感抗提高系统稳定性的方法。相对于传统的直接在转子侧电流环中引入虚拟感抗,在设计基于虚拟感抗的控制器时,充分考虑锁相环耦合弱电网扰动对双馈风电机组运行稳定性带来的不利影响,提出了改进的控制方法。通过广义奈奎斯特判据证明了该方法能有效提高弱电网条件下双馈风电机组的运行稳定性。在MATLAB/Simulink中搭建了1.5 MW的双馈风电机组详细模型,通过仿真验证了所提改进控制器对提高系统稳定性的有效性。

Control Method of Improved Virtual Inductance for DFIG Based Wind Turbine Under Weak Grid Condition

The operation stability of doubly-fed induction generator(DFIG)under weak grid condition has been a focus of research recently. The equivalent input admittance model of DFIG based wind turbine is built in synchronous reference frame. System dynamics, phase-locked loop(PLL)and rotor side controllers including power controller and current controller are considered in this model. The influence of rotor inductance on the system stability is investigated based on the generalized Nyquist criterion(GNC), which proves that the incensement of rotor inductance has a positive impact on the system stability. PLL is a critical component in the system, which may propagate the grid voltage perturbations to the control system and have an adverse impact on the stability of DFIG based wind turbine system. Compared with the conventional virtual inductance based control strategy, the improved control strategy takes the influence of PLL dynamics into consideration. GNC proves that the proposed method can effectively improve the operation stability of DFIG based wind turbine under the weak grid condition. An 1. 5 MW DFIG based wind turbine detailed model is built in MATLAB/Simulink and simulation results verify the validity of theoretical analysis.