基于小波理论的变压器保护算法

Power Transformer Protection Algorithm Based on Wavelet Transform

正确区分电力变压器励磁涌流和内部故障电流是变压器保护中一个尚未得到完善解决的问题.本文利用仿真软件Saber,综合考虑电路、磁路2个方面,建立了考虑磁滞效应和饱和效应的变压器仿真模型,可以实现对励磁涌流和包括匝间短路的多种故障情况进行全面系统的仿真计算.提出一种基于小波变换来正确区分励磁涌流和内部故障,以及区分内外部故障的算法,在大量的仿真基础上,提出了该算法的整定值,并对该算法的灵敏度以及其所需的采样频率进行验证.从理论角度得出CT饱和不影响该算法的结论.

How to distinguish the inrush current and internal fault current is a problem that isn＇t resolve well. A - former model considering the hysteresis effect and the saturation is presented first and magnetic inrushes and short-circuit faults are simulated with this model. This paper proposes a new wavelet-based method to identify an internal fault and distinguish it from an inrush current or an external fault. Under the large quantity simulation, the threshold and the frequency satisfy to the algorithm is presented and tested. The paper draws a conclusion the CT＇s saturation does not affect the algorithm.