基于小波迹方法的局部放电信号消噪研究

在检测电力系统变压器稳定性时,通常会发现变压器放电信号存在各种各样的干扰,尤其是噪声干扰。文章提出一种基于传统小波迹方法的平稳小波迹阈值消噪方法,有效消除了信号采样中的噪音。通过重新定义小波迹字典的方法,改进了传统小波方法中的不足。对所要处理的放电信号进行循环平移,有效消除小波基的平移依赖性,提高小波变换在奇异点附近的特殊性,从而达到消除随机振荡的目的。通过与传统小波包消噪和传统小波消噪的比较,选取阈值、小波基和分解层数,得到了信号消噪的最佳值,进而构建一个适用于局部放电信号研究的平稳小波迹阈值消噪方法。结合MATLAB仿真实验信号和部分某变电站变压器局部放电实际信号验证,该方法能有效抑制局部放电噪声干扰,提取有效信号,消噪效果优于传统小波和小波包方法,可以达到识别的需求。

Research on Denoising of partial discharge signal based on wavelet trace method

In the detection of power system transformer stability, it is usually found that the transformer discharge signal has a variety of interference, especially noise. Aiming at the noise interference of transformer discharge signal, this paper presents a noise reduction method based on wavelet trace method. In this method, the traditional wavelet denoising algorithm has been improved. Based on the traditional wavelet transform, the wavelet trace dictionary is redefined, and the discharge signal to be processed is circularly translated. This method can effectively eliminate the translational dependence of wavelet basis and improve the particularity of wavelet transform in the vicinity of singularity so as to eliminate the random oscillation. By comparing with traditional wavelet packet de-noising and traditional wavelet denoising, threshold, wavelet base and decomposition layer number are selected, and the best value of signal denoising is obtained. Then a stationary wavelet trace threshold de-noising method suitable for the study of partial discharge signal is constructed. Combined with MATLAB simulation experiment signal and partial transformer partial discharge actual signal verification, this method can effectively restrain the noise of partial discharge and extract the effective signal. The noise elimination effect is better than the traditional wavelet and wavelet packet method, which can meet the needs of identification.