基于改进经验小波变换及互谱相位差谱的供水管道泄漏声振动定位方法

Leak location based on the improved EWT and cross-power phase difference spectrum of vibro-acoustic signal in water-supply pipelines

针对供水管道泄漏声振动信号的信噪比较低导致用于时延估计泄漏定位误差大的问题,提出基于改进经验小波变换及互谱相位差谱的供水管道泄漏定位方法。首先采用小波包分解得到不同尺度的信号能量谱,根据小波包能量谱局部极小值的分布自适应确定频带分割区间,解决了传统经验小波变换中频谱划分问题;然后基于频带分割区间构建正交小波滤波器组对信号进行经验小波变换分解得到多个分量,根据相关系数选取有效分量,同时利用有效分量的互谱相位差谱呈水平变化的频带对有效分量信号进行带通滤波,滤除干扰噪声;最后对滤波后的信号进行互相关时延估计来确定泄漏位置。仿真及实验结果表明,该方法能够有效的实现供水管道泄漏定位,并与互相关、VMD与互谱分析相结合的泄漏定位方法相比,平均相对定位误差分别减少6.7倍和1.5倍。

The low signal-to-noise ratio of leakage vibration signal in water-supply pipelines(WSP)may result in the large leak location error.To address this problem,a leak location method based on the improved empirical wavelet transform(EWT)and cross-power phase difference spectrum is proposed.Firstly,the local minimum of wavelet packet energy spectrum is used to segment the signal spectrum.The signal energy bands of different scales are achieved through wavelet packet decomposition.The distribution of energy value is used to determine spectrum segmentation interval,which solves the spectrum division problem of EWT.Then,the leakage vibro-acoustic signal is decomposed into multiple components by EWT according to the spectrum segmentation interval.Effective components can be selected according to the correlation coefficients,and the effective components are band-pass filtered using the frequency band with horizontal variation of the cross-power phase difference spectrum of the effective components.Finally,the leakage can be determined by cross-correlation time-delay estimation of the filtered effective component signal.Compared with cross-correlation,variational mode decomposition and cross-spectrum analysis,simulation and experimental results show that the proposed method can effectively locate the leak point,and the average relative location error is reduced by 6.7 times and 1.5 times respectively.