Research And Application Of Leakage Location Algorithm For Water Supply Pipeline Based On VMD

Water supply pipeline leakage has become an important problem in the world,so it is particularly important to find and locate the leakage in time and repair it in time.Using pressure signal and vibration signal to detect and locate the leakage of water supply pipeline is a popular solution in recent years.When the pipeline leaks,the pressure signal and vibration signal carry a lot of pipeline leakage information,but usually,due to the existence of channel noise,the signal will produce distortion in the transmission process,these changes often cover up the information carried by the signal.For example,a large amount of noise will be added in the process of signal propagation,and the size of noise is related to the channel environment.In signal processing,we not only need to avoid signal distortion as much as possible,obtain complete information from the signal,but also need to enhance the robustness of signal processing.Therefore,a good signal processing method is very important.Traditional signal decomposition methods,such as empirical mode decomposition(EMD),wavelet decomposition,empirical wavelet transform(EWT)and variational mode decomposition(VMD)are used to decompose the signal into different modes.By exploring the statistical characteristics and frequency characteristics of the modes,the mode of the leakage signal is found and the signal is reconstructed to achieve the purpose of signal denoising.Although these signal decomposition algorithms improve the detection accuracy of leakage location to a certain extent,there are still large positioning errors.The main reasons can be summarized as follows: 1.It can not accurately identify the mode of leakage signal,and some correlated interference will seriously affect the judgment of leakage components to a great extent;2.The quality of signal decomposition can not be guaranteed.After the signal is decomposed,there will be mode aliasing or excessive decomposition,which may cause the leakage signal to carry too much noise or cause signal distortion,thus affecting the accuracy of leakage location.Therefore,this paper has done a lot of research from these two angles to further improve the accuracy of leakage location.In order to solve these problems,an improved adaptive variational mode decomposition(IAVMD)algorithm is proposed.Since the leakage signal is a kind of multi-modal non-stationary random signal,the influence of the bandwidth of each mode on the signal decomposition should be considered in the signal decomposition.Therefore,a quadratic penalty term α is added to the bandwidth of each signal mode,which is updated with the iteration.Finally,this method can adaptively determine the quadratic penalty term α of each band limited intrinsic mode functions(BLIMF)according to the frequency characteristics of the signal.At the same time,the energy loss coefficient and the correlation between the adjacent modes is used as the evaluation index to determine the optimal number of modes K.Compared with the traditional EMD and VMD algorithm,the proposed method can get higher signal fidelity,thus improving the accuracy of leak location detection.In the research of leakage location of water supply pipeline,the estimation error of leakage location depends on the noise level of the signal.The traditional method of noise reduction usually needs to estimate the parameters of the noise model first.This kind of method is only limited to random noise,and does not consider whether there is periodic noise and some components that are not related to leakage.In this paper,an adaptive denoising algorithm based on IAVMD is proposed.This method does not need to know the background noise of the signal,it can adaptively select the signal mode related to leakage,and finally reconstruct all signal modes to achieve the purpose of denoising.