小波变换的二抽取环节对行波测距精度的影响

在利用小波变换模极大值表征行波波头到达时刻方法的基础上,详细分析了带有二抽取环节的小波变换行波测距算法引起的测距误差,由于二抽取环节在某些条件下会把代表行波波头到达时刻的小波变换模极大值抽取掉,导致提取的行波波头到达时刻偏移,从而引入测距误差。并进一步提出了通过平滑处理故障首尾数据的优化方法提高行波波头提取的可靠性。理论分析和EMTP结果表明,无二抽取环节的小波变换行波测距算法能够有效提高测距精度。

Influence of down- sampling by two in wavelet transform on precision of traveling wave fault locating

Based on the method that indicates the arriving time of the traveling wave head using the maximum module of the wavelet transform,the fault locating error caused by the wavelet transform with down-sampling by two is analyzed in detail.Under some conditions,the maximum module of wavelet transform may be missed because of down-sampling by two.An optimization method is proposed to improve the reliability of getting the traveling wave head,smoothing both beginning and ending data.The theoretical analysis and EMTP(ElectroMagnetic Transient Program) simulations show that,the precision of the traveling wave fault locating can be improved without down-sampling by two.