接于弱电网的双馈感应发电机在定子故障情况下的无功功率控制策略

针对双馈感应发电机(DFIG)发生定子绕组匝间短路(SWITSC)故障后对弱电网并网点电压稳定性的影响问题,构建了含SWITSC故障DFIG的弱电网模型。通过仿真分析和理论分析得到如下结论:DFIG发生SWITSC故障后输出无功、有功功率将变化进而导致弱电网并网点电压降落,而不同的输电线路阻抗比、电网强弱程度以及DFIG的SWITSC故障严重程度均会影响DFIG的输出无功、有功功率。针对上述影响,基于维持并网点电压稳定的目的,提出了一种改进的DFIG输出无功功率控制策略。仿真结果表明,该控制策略充分发挥了DFIG的无功功率调节能力,在SWITSC故障情况下可以有效遏制并网点电压的降落,在正常情况下则与常规控制策略等效。

Reactive power control strategy of DFIG connected to weak network with stator fault

The weak network model of DFIG(Doubly-Fed Induction Generator) with SWITSC(Stator Winding Inter-Turn Short Circuit) fault is established for investigating the influence of SWITSC fault on the voltage stability at the PCC(Point of Common Coupling). By the theoretical analysis and simulation, it is concluded that the reactive and active power output of DFIG will change after the SWITSC fault occurs, which causes the voltage drop at the PCC, and different impedance ratios of transmission line, strength levels of grid and severity degree of SWITSC fault all have influences on the reactive and active power output of DFIG. In order to maintain the voltage stability of PCC, an improved control strategy for DFIG reactive power output is proposed considering the above influences. Simulative results show that the improved control strategy is equivalent to the conventional control strategy in normal conditions and can fully exploit the reactive power regulation capability of DFIG to reduce the voltage drop of PCC effectively when SWITSC fault occurs.