双馈电机低电压穿越特性分析

Analysis of low voltage ride through characteristics of DFIG

双馈电机低电压穿越研究多集中于改进励磁控制策略,而针对故障穿越期间的功率转矩等特性分析较少。为揭示双馈电机控制策略的本质,本文推导了双馈电机转子侧电压电流在故障期间的暂态特性,分析表明低电压穿越困难的根源在于转子侧感应电动势过大,影响了变流器对转子电流的控制。本文对比不同的改进励磁策略,得出上述控制策略的本质是通过漏感压降抵消部分转子感应电动势,从而维持变流器可控运行。

The research on low voltage ride through of DFIG mostly focuses on improving the excitation control strategy,but less on the analysis of characteristics such as power and torque during fault ride through.In order to reveal the essence of the DFIG control strategy,this paper deduces the transient characteristics of the DFIG rotor-side voltage and current during faults.The analysis shows that the root of the difficulty of low voltage ride through is that the induced electromotive force on the rotor side is too large,which affects the control of the rotor current by the converter.This paper compares different improved excitation strategies,and concludes that the essence of the above control strategy is to offset part of the rotor induced electromotive force through the leakage inductance voltage drop,so as to maintain the controllable operation of the converter.