Acoustic Emission Coherent Localization Method for Fluid Pipeline Leakage Based on Empirical Mode Decomposition

Abstract

The invention relates to a coherent positioning method for fluid pipeline leakage acoustic emission based on empirical mode decomposition, and belongs to the field of pipe inspecting. The coherent positioning method for fluid pipeline leakage acoustic emission based on empirical mode decomposition adopts empirical mode decomposition to perform eigen mode decomposition on a leakage acoustic emission signal, performs coherence analysis on two route leakage signals to extract a coherent frequency band of the leakage signal, and meanwhile, performs coherence analysis on the eigen mode. The eigen mode is selected by the coherent frequency band, thereby the coherent frequency band of the eigen mode within the coherent frequency band of the leakage signal is a valid eigen mode. A new leakage signal is reconstructed from the valid eigen mode for correlation time delay estimation and estimation. At the same time, a propagation velocity of the leakage signal is determined according to the coherent frequency band, so that the location of a leakage point is determined on the bases of the correlation time delay estimation, the propagation velocity and the distance between two sensors. The coherent positioning method for fluid pipeline leakage acoustic emission based on empirical mode decomposition can improve the correlation and signal-to-noise ratio of the leakage signal and reduce the tine delay estimation error, thereby reducing the leakage positioning error.

Description

technical field [0001] The invention belongs to the field of pipeline detection and relates to an acoustic emission coherent location method for fluid pipeline leakage based on empirical mode decomposition. Background technique [0002] As an efficient and convenient fluid transportation method, pipeline has been widely used in the transportation of natural gas, oil and other fluids. Due to natural or man-made reasons: pipeline aging, corrosion, geological subsidence, third-party damage, etc., pipeline leakage occurs from time to time. Leakage of fluid pipelines causes waste of resources, environmental pollution, and even vicious accidents such as explosions and poisonings, posing a serious threat to people's lives and property. Therefore, the detection and location technology of fluid pipeline leakage is very necessary to effectively reduce or avoid the harm caused by pipeline leakage. [0003] Acoustic emission technology, as a real-time online non-destructive testing me...

AI Technical Summary

Problems solved by technology

This method overcomes the problem of large positioning errors caused by the dispersion of leaked acoustic emission signals. It essentially uses a time-frequency positioning method based on the cross-correlation function of a single dominant mode signal, but the actual leaked acoustic emission signal is multiple Modal signals (bending mode, torsional mode, longitudinal mode, and fluid-dominant mode), which will lead to weak correlation of the leakage signals collected at both ends of the leak when performing cross-correlation analysis, resulting in large cross-time-frequency positioning errors

Chinese patent (CN105627107A) discloses a single-sensor modal acoustic emission location method for fluid pipeline leakage. The method uses time-frequency analysis to extract the time difference of arrival of pipeline leakage acoustic emission multimodal signals. According to different modal signals of the same frequency component The location of the leakage point can be determined by the speed difference and arrival time difference, which can effectively solve the problem of large positioning errors caused by the multi-mode and dispersion characteristics of the leakage signal. However, this method has high requirements on the signal-to-noise ratio and the pipeline leakage detection distance is limited.

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