基于小波和高阶PDE的电缆局部放电去噪研究

Research on de-noising of cables partial discharge based on wavelet and high order PDE

局部放电(PD)试验是检测电力电缆绝缘性能的重要手段,由于试验现场电磁环境比较复杂,提取所得的PD信号已被噪声淹没。为得到较为真实的PD信号,提出了一种基于小波变换和高阶偏微分方程(PDE)相结合的去噪方法。利用小波变换提供较好的局部放电信号预处理和后处理平台,对低频子信号进行四阶PDE迭代去噪,同时采用效果评价指数信噪比(SNR)作为迭代终止条件。将该方法的去噪效果与传统的小波阀值去噪效果进行了比较,经过计算和仿真分析表明,文中方法能够较好的保留信号边缘与细节,比传统小波阀值去噪具有更优越的去噪性能。

Partial discharge(PD)test is an important means to detect the insulation performance of power cable.Because the electromagnetic environment of the test site is complicated,the extracted PD signal is submerged by noise.In order to get a more real PD signal,this paper proposes a de noising method based on wavelet transform and high order partial differential equation(PDE).It adopts wavelet transform to provide better pre processing and post processing platform of partial discharge signal,and utilizes the fourth order PDE to iterate the low frequency sub signal.At the same time,the signal to noise ratio(SNR)is used as the iteration termination condition.The de noising effect of this method is compared with the traditional wavelet threshold de noising effect.Finally,the experimental and simulation results show that this method can suppress noise effectively and keep the property of edge and detail.It has better de noising performance than traditional wavelet threshold de noising method.