能量变换器内部单相接地故障建模与分析

Modeling and analysis of internal single phase-to-ground fault in Powerformers

为了研究能量变换器(Powerformer)定子绕组内部短路故障,以直接相量法为基础建立了能量变换器定子绕组内部单相接地故障分析的数学模型,并给出了基于Matlab/Simulink的仿真模型。该模型不仅可以对能量变换器中性点经高阻接地和经消弧线圈接地情况进行仿真,还能对沿绕组内部不同位置处发生的故障进行仿真。对一台130kW/5kV的能量变换器仿真结果表明,中性点经消弧线圈接地的接地电流很容易达到安全电流以下;而且与同容量的常规发电机相比,能量变换器的故障电流远小于常规发电机。

In order to study internal single phase-to-ground faults in Powerformers, a mathematical model of Powerformer, which can analyze internal single phase-to-ground fault in stator windings, is proposed on the basis of a direct phase representation. A simulate model is built on Matlab/Simulink. The models not only simulate a single phase-to-ground fault when the generator neutral point is either high resistance ground or arc-suppression coil ground, but also perform when a single phase-to-ground fault occurs at different locations along the winding. The result based on a 130 kW/5 kV Powerformer shows that the grounding current is less than safe current when arc-suppression coil grounding. And compared to the same capacity conventional generator, the fault current of Powerformer is much smaller than the conventional generator.