电能质量信号的改进S变换降噪方法

Power quality signal denoising using modified S-transform

利用改进S变换提出了一种电能质量信号的降噪方法。首先提出了能量聚集度概念以此确定改进S变换的时频分辨率;接着利用白噪声在改进S变换域的分布特性检测电能质量有用信号能量在改进S变换时频面的区域;然后采用硬阈值方法修正信号的改进S变换值,即保留其中的有用信号部分而其余部分置零;最后通过改进S反变换得到降噪后的信号。通过几种电能质量信号降噪处理的仿真实验以及和小波方法进行降噪性能比较的结果,验证了所提方法的有效性。

This paper presents a new approach of power quality disturbance denoising using modified S-transform. The concept of energy congregation level is defined for determining the optimal time-frequency resolution. The distribution property of white noise in modified S-transform domain is employed to detect the useful power quality region in time-frequency plane. Hard threshold algorithm is used to verify the value of the modified S-transform matrix elements. Inverse modified S-transform is adopted to get the denoised waveform. In the end of the paper simulation results are used to illustrate the validity of the proposed method and the result comparison with wavelet-based method is given.