基于VMD的电力电缆局部放电信号自适应阈值降噪方法

局部放电(Partial Discharge, PD)用于高压电缆在线监测时,采集到的信号包含多种噪声,白噪声是最常见、影响最广泛的一种。为了抑制白噪声的影响,提出了一种基于变分模态分解(Variational Mode Decomposition, VMD)的局部放电信号降噪方法。采用变分模态分解对含噪局部放电信号进行分解,得到频率从低到高的模态分量后,计算各个变分模态分量的峭度值,选取脉冲特征分量进行重构,利用小波自适应阈值对重构信号再次降噪。与小波变换阈值法对比在不同噪声环境下的降噪结果,结果从均方误差、波形相似系数定量优于小波标准软阈值降噪法和小波全局硬阈值降噪法。仿真和现场实验结果表明,该方法可以有效去除噪声信号,能够较为完整地保留原始信号波形。

An adaptive threshold value noise suppression method for detecting partial discharge of power cables based on variational mode decomposition

When partial discharge (PD) measurement is used to monitor the power cables and analyze the insulation conditions, the collected signals often contains a variety of noises, in which white noise is the most common and most influential type. In order to suppress the influence of white noise, a white noise reduction method for PD signal based on Variational Mode Decomposition (VMD) is proposed. Firstly, the PD signal is decomposed by VMD, which obtains Intrinsic Mode Functions (IMFs) with low to high frequency. Then the kurtosis value of each IMF is calculated respectively. The corresponding IMFs are selected to be reconstructed. And the reconstructed signal is de-noised again by the wavelet unbiased estimation using adaptive threshold. Compared with different noise environments and de-noising methods, the results show that the de-noising effect about errors of mean square and quantity of waveform similarity coefficient based on VMD is better than that of wavelet standard soft threshold de-noising method or global hard threshold method. The simulation calculations and monitoring experiments show that this method can not only effectively remove the noise signal, but also preserve the original signal waveform completely. This work is supported by Science and Technology Support Xinjiang Project of Xinjiang Uygur Autonomous Region (No. 2018E02073), Henan Science and Technology Key Project (No. 182102310936), and Project of the Quality and Technological Supervision of Henan Province (No. 2018ZJ52).