In order to prevent the wrong action of transformer differential protection,a new method to identify inrush current based on wavelet coefficient distribution is presented in this paper.This method is based on multi-resolution analysis in wavelet transform theory,after the wavelet transform the obtained two scales wavelet coefficients were extracted,calculate the variance changes,and set a reasonable threshold,to distinguish between inrush current and fault current.Application of MATLAB toolbox to build the transformer inrush current and fault current simulation model,simulation results show that this method can quickly and effectively identify the inrush current and fault current,to ensure the correct operation of differential protection.%为防止励磁涌流导致变压器的差动保护误动作,文章提出了一种以小波系数分布为判据的励磁涌流识别的新方法;该方法以小波变换中多分辨分析为理论依据,通过小波变换后对所得二尺度上的小波系数进行提取,计算其方差变化率来表示小波系数的变化情况,并设定合理的阀值,来对励磁涌流与故障电流进行区分;应用MATLAB工具箱搭建变压器励磁涌流与故障电流仿真模型,进行大量仿真,仿真试验结果表明,该方法能够快速有效的对励磁涌流与故障电流进行识别判断,克服了传统方法的不足,保证差动保护的正确动作,具有很高的应用前景.
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