基于小波变换抑制局部放电监测中平稳性干扰的滤波器的研究

根据局部放电（ＰＤ）信号的非平稳统计特性，提出了一种用于抑制窄带干扰和测试设备产生的随机性干扰的新方法。该方法将多分辨分析和硬阈值结合起来构成一种基一皮变换的平稳－非平稳滤波器（ＷＴＳＴ－ＮＳＴ），用于提取局部放电信号。实验结果表明，该方法能有效地实现局部放电信号和器材怕信号的分离，并具有计算时间短、提取出的ＰＤ信号波形畸变小等优点，有用于局部放电的在线检测中。

STUDY ON WTST-NST FILTER USED FOR SUPPRESSION OF STATIONARY NOISES IN PD MONITORING

Partial Discharge(PD) on line monitoring has been extensively used for evaluation of the insulation condition of electrical equipment in service. However, its sensitivity and reliability are affected by strong noises, such as communication signals and random noises produced by detection system itself. In this paper, a novel method for suppressing stationary noises is presented based on the nonstationary of PD. The proposed algorithm combines multiresolution analysis with hard threshold in order to construct a wavelet transform based stationary nonstationary filter (WTST NST). The experimental results indicate that this method can extract the PD signal from noises effectively. Compared to other methods adopted to extract PD signals, WTST NST filter performs more accurately and with less computation time. It has been used in PD on line monitoring system successfully.