一种可提取受波动干扰的电压暂降特征的信号处理方法

Signal Processing Method for Extracting the Voltage Sag Feature with Voltage Fluctuation Interference

电压暂降信号中混杂的噪声会模糊暂降起止时刻的检测,而电压波动的干扰则会影响暂降幅值深度的确定,对此设计了一种基于变分模态分解(variational mode decomposition,VMD)的消噪方法及结合小波变换定位的三阶导数普罗尼(third derivative method⁃Prony,TDM⁃Prony)算法。首先将信号进行VMD分解,得到数个有限带宽的固有模态分量(band⁃limited intrinsic mode functions,BLIMFs),对获得的高频BLIMFs进行SURE阈值去噪,然后与低频分量进行重构。然后,对重构信号进行小波变换,定位电压波动及电压暂降的起止时刻,并利用TDM⁃Prony算法对波动信号段进行拟合以获取其信息,实现波动与暂降的分离;最后,对获得的干净暂降信号进行希尔伯特(Hilbert)变换可得其暂降幅值及持续时间。仿真结果表明,文中设计算法可有效地提取受波动信号的干扰的电压暂降特征。

The noise mixed in the voltage sag signal will obscure the start and end time of the voltage sag in detec⁃tion,and the interference of the voltage fluctuation will affect the determination of the of the voltage sag depth.This paper proposes a denoising method based on the variational mode decomposition(VMD),and designs a TDM(third derivative method)⁃Prony algorithm combined with wavelet transform.First,the signal is decomposed via VMD to ob⁃tain several band⁃limited intrinsic modal components(BLIMFs),and the acquired high⁃frequency BLIMFs are de⁃noised by SURE threshold then reconstructed with the low⁃frequency components.Then,wavelet transform is per⁃formed on the reconstructed signal to locate the start and end time of voltage fluctuation and voltage sag,and TDM⁃prony algorithm is used to fit the fluctuation signal segment to obtain its information,so as to achieve the separation of fluctuation and sag.Finally,Hilbert transform is performed on the clean sag signal to obtain the amplitude and dura⁃tion of voltage sag.Simulation results show that the designed algorithm can effectively extract the feature of voltage sag interfered by fluctuating signals.