Analysis Method Of Infrasonic Wave Signal Of Pipeline Leakage

With the rapid development of urbanization in China,the water supply system plays an important role in ensuring normal operation of the city,and water pipeline is an important part of the whole system.Due to the influence of various factors,pipeline leakage accident occurs occasionally,causing a lot of water resources waste.Therefore,it is necessary to do research on the water pipeline leakage detection.Water pipeline leakage would generate infrasonic wave signal,and the frequency is less than 20 Hz.Based on the analysis of leakage infrasonic wave signal,extracting the characteristic variables which can be used to judge the condition of water pipeline.In this thesis,the research on the analysis method of infrasonic wave signal of water pipeline leakage includes three aspects: research on denoising method of infrasonic wave signal,research on feature extraction method of infrasonic wave signal and analysis of actual infrasonic wave signal of water pipeline leakage.(1)Research on denoising method of infrasonic wave signal.On the basis of the theory analysis of adaptive filtering and EMD,simulate adaptive noise cancellation based on LMS,RLS algorithm and EMD infrasonic wave signal denoising.According to the effect of infrasonic wave signal denoising based on EMD denoising is not ideal,in this thesis,the combination of adaptive noise cancellation and EMD denoising is used to improve EMD denoising.The simulation result shows that denoising effect is improved obviously with improved EMD.(2)Research on feature extraction method of infrasonic wave signal.Through theoretical and simulation comparison of Short-time Fourier transform,Wavelet transform and HHT,this thesis chooses HHT to extract feature of infrasonic wave signal.EMD,as a part of HHT,would produce pseudo component after decomposition,influencing feature extraction accuracy of infrasonic wave signal.In this thesis,an improvement measure of HHT is adding pseudo component and later low order component as a new component.The simulation result shows that the accuracy of improved HHT feature extraction accuracy is improved obviously.(3)Analysis of actual infrasonic wave signal of water pipeline leakage.Collect infrasonic wave signal of four conditions(normal operation,leakage start,continuous leakage,leakage end)of tap-water pipeline through experiment and use the method of this thesis sum up to complete infrasonic wave signal denoising and feature extraction,obtaining feature of infrasonic wave signal of different stages of pipelineleakage.In this thesis,the analysis object is infrasonic wave signal of water pipeline leakage.Research on denoising and feature extraction of infrasonic wave signal and obtain infrasonic wave signal's feature of different stages of pipeline leakage finally.It is expected that the research result of this thesis can provide some reference for the future water pipeline leakage detection.