双馈异步发电机单相接地故障瞬态特性研究

Transient characteristic research of doubly-fed induction generator during single-phase grounding fault

为了便于研究DFIG在不对称电压跌落下低电压穿越运行的控制策略,有必要对不对称电压跌落时DFIG的瞬态特性进行研究。基于DFIG定、转子磁链的瞬态变化机理,对DFIG单相接地故障瞬态特性进行研究,推导出了DFIG在发生单相接地故障时的定、转子电流,电磁转矩,输出有功功率与无功功率的解析表达式,并分析得到影响单相接地故障时电磁过渡过程的主要因素。在Matlab/Simulink中搭建了1.5 MW双馈异步发电机单相接地故障仿真模型。仿真结果和解析计算结果高度吻合,证明了推导的解析表达式的正确性和有效性,为双馈异步发电机不对称LVRT控制策略提供了理论基础。

In order to research the control strategy of low voltage ride through （LVRT） of DFIG during the asymmetric voltage sag, it is necessary to research the transient characteristic of DFIG during the asymmetric voltage sag. This paper utilizes the transient change mechanism of DFIG stator and rotor flux in the case of single-phase grounding fault, deduces and obtains analytical expressions about stator transient current, electromagnetic torque, output active power and reactive power of DFIC~ On the basis of above, the main factors are got which affect single-phase grounding fault electromagnetic transient process. And simulation model of 1.5 MW DFIG during single-phase grounding fault is built on MATLAB/Simulink, the simulation results are closely consistent with the analytical calculation results, which shows the correctness and effectiveness of the analytical expressions derived. Analysis of this paper can provide theoretical basis for control strategy of asymmetric LVRT.