Cohen类时频分布比较及其在局部放电信号处理中的应用

系统地以参函数的角度介绍了6种典型的Cohen类时频分布。从理论和应用效果上分析了各分布的交叉干扰项衰减和时频分辨率性能。针对局部放电信号的非平稳性,展现了各分布在处理仿真和实际脉冲信号的应用效果。试验结果表明,平滑伪Choi-Williams分布(SPCWD)对局放脉冲非平稳信号引发的短时变化具有高度的敏感性,更为适合表征局放脉冲信号的时变信息。据此,可提取单个脉冲波形的时频特征参数、分析多个连续放电脉冲的时频变化,从而用于放电类型的模式识别以及深入研究绝缘系统中的局部放电机理。

Comparison of Cohen Class Time-frequency Distribution and Application on PD Singal Processing

Based on parameterization functions,this paper introduces six typical time-frequency energy distributions known as the Cohen′s class.From a theoretical point of view and application,the interference cross-terms attenuation and time-frequency resolution of those distributions have been discussed respectively.According to the characteristic of non-stationary partial discharge(PD) signals,these distributions have been applied to simulation PD signals and the real ones.The results show that the smoothing-pseudo Choi-Williams distribution(SPCWD) provides a high sensitivity to variation in short duration of the non-stationary PD signal, which is available to extract the time-varying information.This distribution provides a powerful tool to evaluate parameters for single PD pulse shape and analyze time-frequency variation of PD sequence,which can be used to PD pattern recognition and in-depth study of PD mechanism in the electrical insulation system.