电网电压跌落情况下双馈风力发电机电磁过渡过程及控制策略

Electromagnetic Transient Process and Control Strategy for Doubly-Fed Wind Power Generator Under Grid Voltage Dip

分析了电网电压跌落时,双馈风力发电机(DFIG)暂态电磁过渡过程中各分量的变化规律,通过求解时域下的微分方程,得到了定、转子电流不仅包含本身所应具有的分量而且还含有直流分量和转速频率的交流成分的结论。仿真频谱分析所得结果与理论分析一致,阐明了转子侧产生过电压、过电流的根本原因。在此基础之上,提出了基于考虑定子磁链暂态过渡过程的双馈发电机低电压穿越(LVRT)控制策略,并进行了仿真对比分析。结果表明,与传统的矢量控制方案相比,改进的控制策略可以有效抑制转子侧的冲击电流,提高了双馈发电机在电网电压跌落下的不间断运行能力。

This paper firstly analyses the electromagnetic transient process respective compo- nents change law of doubly-fed induction generator（DFIG） under the grid voltage dip. Through solving differential equations in time-domain, the results that the stator and rotor currents include not only the components of itself but also DC components and AC components of speed frequency （or are obtained, and simulation spectrum analysis is carried out. The conclusion is consistent between simulation spectrum analysis and theoretical analysis. It expounds the root cause of overvoltage and overcurrent in rotor side. And then, the DFIG low voltage ride-through（LVRT） control strategy based on considering electromagnetic transient process is proposed, improving traditional vector control algorithm. The simulation contrastive analysis shows that the improved control strategy can restrain the rotor current impact effectively, and increase the uninterrupted operation ability of DFIG under grid voltage dip.