电网对称故障下无刷双馈电机低压穿越分析

Low-voltage Ride-through Analysis of Brushless Doubly-fed Machine Under Grid Symmetrical Fault

通过控制电机转子磁场定向得到同步坐标系下的仿射非线性状态空间模型,针对无刷双馈发电机组机侧控制器应用反馈线性化解耦控制方法。在电网电压三相对称跌落下,分析控制电机定子电流和控制电机定子反电动势的暂态响应。推导得出BDFM稳定运行时,控制电机转子磁链与功率电机定子电压满足线性比例关系,在低压穿越模式下来改善系统控制性能和稳定性,提高机组低压穿越能力。仿真结果证明了理论分析的正确性和有效性。

In this paper,an affine nonlinear state model is obtained by controlling the rotor field orientation in a synchronous reference frame.Feedback linearization decoupling control method is implemented on the controller of a brushless doubly-fed machine(BDFM).During a three-phase symmetrical grid voltage dip,the transient responses of the control machine’s stator current and stator counter-electromotive potential are analyzed.According to the expressions,it is shown that when BDFM is operating stably,there is a linear proportional relationship between the control machine’s rotor flux linkage and the power machine’s stator voltage;moreover,a low-voltage ride-though mode is presented to improve the control performance and stability of the system,and guarantee the capability of LVRT of machines.Simulation results validate the accuracy and effectiveness of the theoretical analysis.