基于小波变换的变压器励磁涌流的新判据

New Judgment of Transformer Inrush Current Based on Wavelet Transform

针对识别变压器励磁涌流和内部故障电流的问题,提出一种利用小波分解识别两种电流的新判据。在PSCAD/EMTDC软件中搭建三相变压器的仿真模型,得到励磁涌流和内部故障电流的波形,通过MATLAB小波包对电流波形信号进行尺度的分析,提取4尺度波形的特征,利用差值法得到新判据。理论分析与仿真实验结果表明,该判据能准确、可靠地识别变压器励磁涌流和内部故障电流。

Aiming at the problem of identify the inrush current and internal fault current of transformer,a new judgment to identify two kinds of current by wavelet decomposition is put forward.The simulation model of three-phase transformer in PSCAD/EMTDC software,and the waveform of inrush current and internal fault current is obtained.The MATLAB wavelet packet is used to analyze the current waveform signal,and a new judgment is obtained by the difference method form the extracting characteristics of the4scale waveform.Theoretical analysis and simulation results show that this judgment can identify the inrush current and internal fault current correctly and reliably.