基于有限元分析的双馈异步发电机定子绕组匝间短路故障诊断研究

Simulation on Inter-turn Short Circuit Faults of Stator Winding Via Finite-element Method for DFIG

笔者基于有限元分析软件Maxwell 2D建立了双馈异步发电机的仿真模型,通过改变模型中短路匝数和短路电阻的大小来模拟电机的不同短路情况,对不同情况下的电机进行仿真计算得出:定子发生匝间短路故障后,会在定子中产生负序电流,并随着故障严重程度的增加而增大,同时负序电流会受到电源不对称的影响,在用负序电流进行故障诊断时,需要补偿这些非电机故障因素的影响,同时负序电流也会受到电机负载情况的影响,且随着负载的增大负序电流有微弱增大。另外,定子发生匝间短路故障后,定子三相电流不再对称,故障相电流恒最大,而非故障两相的相位差偏离120°最大,且随着故障的加剧而明显增大。

We establish a doubly-fed induction generator（DFIG） model with the finite element analysis software Maxwell 2D to simulate different inter-turn short circuit faults of stator winding with varying＂ short circuit number and resistance. Simulations show that the inter-turn short circuit faults induce negative sequence current in DFIG stator, and the negative sequence current increases with the severity of inter-turn short circuit fault. Moreover, symmetric power source and load also influence the negative sequence current. So the impacts of these non-fault factors must be compensated when the negative sequence current is used in the fault diagnosis. In addition, as an inter-turn short circuit fault occurs, the stator＇s three-phase current is no longer symmetric, where the fault-phase current is always the biggest, but the phase separation of other two phases without fault gets the,maximum 120°.