电网故障下双馈风机电磁暂态分析

Electromagnetic Transient Analysis of Doubly Fed Wind Turbines Under Grid Faults

为实现双馈风机的低电压过渡,分析双馈风机在电网故障时定、转子电流的变化趋势及其与磁链的关系,从双馈风机的基本方程出发,对双馈风机的故障电流、电磁暂态、谐波及冲击电流进行理论推导,分析了有功、无功指令值,电压跌落程度与冲击电流最大值之间的关系,认为定子磁链中激发的暂态直流分量和负序分量是引起定、转子过电流的根本原因。仿真和实测结果证明了上述理论分析的正确性,得出的结论对设计双馈风机的控制策略、实现低电压过渡具有实际意义。

In order to realize the low voltage ride through(LVRT)of the doubly fed in duction generator(DFIG),starting from the basic equation of DFIG,the fault current,electromagnetic transient,harmonic and impulse current of DFIG are theoretically deduced,and the relationship among active and reactive command value,drop depth and the maximum impulse current is analyzed.It is considered that the transient DC component and negative sequence component excited in stator flux are the fundamental cause of stator and rotor overcurrent.The simulation and measured results show that the above theoretical analysis is correct,and the conclusions are meaningful to realize the LVRT function in the design of the new control strategy of doubly fed induction generator.