CN-121977176-A - Pipeline leakage point identification and positioning method based on optical fiber vibration signal characteristics

CN121977176ACN 121977176 ACN121977176 ACN 121977176ACN-121977176-A

Abstract

The invention relates to the technical field of optical fiber sensing and pipeline safety monitoring, and particularly discloses a pipeline leakage point identification and positioning method based on optical fiber vibration signal characteristics, which comprises the steps of locking a suspected leakage section based on energy abnormality characteristics and intercepting a two-channel signal to be analyzed by collecting vibration signals along a pipeline; the method comprises the steps of carrying out frequency dispersion characteristic analysis on a two-channel signal, judging the type of a geological layer of a suspected section through a cross-power spectrum phase-frequency relation, extracting an instantaneous frequency main ridge line through time-frequency rearrangement conversion aiming at a non-uniform geological layer signal, adopting a dynamic time warping algorithm to realize nonlinear alignment of characteristic curves, reconstructing distortion correction signals and extracting time delay differences, combining a reference wave speed and a hyperbolic positioning method of dynamic calibration to calculate the spatial position of a leakage point, judging the leakage type based on an accumulated distance threshold value and a regular path characteristic, and solving the problems of signal frequency dispersion distortion, large positioning deviation and indistinguishable leakage types under the non-uniform geological layer.

Inventors

XU LULIANG
JIN XIAOFEI
SHI HAIREN
WU YINGCHUN

Assignees

安徽复盛信息科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260403

Claims (10)

1. A method for identifying and positioning a pipeline leakage point based on optical fiber vibration signal characteristics is characterized by comprising the following steps: Collecting vibration signals along the pipeline through a distributed optical fiber vibration sensing system, identifying a suspected leakage section based on energy abnormal characteristics, and intercepting time domain signals of two adjacent sensing channels in the suspected leakage section as signals to be analyzed of double channels; performing frequency dispersion characteristic analysis on the two-channel signal to be analyzed, and judging whether the geological layer type of the suspected leakage section is a non-uniform geological layer or not through linear analysis on a cross power spectrum phase-frequency curve; If yes, carrying out time-frequency rearrangement conversion on the two-channel signal to be analyzed, extracting a high-resolution time spectrum, and acquiring a frequency component connecting line with the maximum energy along a time axis to form an instantaneous frequency main ridge line; Taking one channel main ridge line as a reference, adopting a dynamic time warping algorithm to carry out nonlinear alignment on the other channel main ridge line to obtain an optimal warping path and an accumulated distance, reconstructing an original time domain signal according to the optimal warping path, and extracting an effective time delay difference; And calculating the spatial position of the leakage point by a hyperbolic positioning method by combining the dynamically calibrated reference wave speed and the effective time delay difference, and identifying the leakage type according to the accumulated distance and the local expansion and contraction characteristics of the optimal regular path.
2. The method for identifying and locating the leakage point of the pipeline based on the characteristics of the optical fiber vibration signal according to claim 1, wherein the method comprises the following steps: The suspected leakage section is identified in the following way: dividing the distributed optical fiber into a plurality of continuous measuring point groups along the axial direction of the pipeline, wherein each group is a sensing channel, selecting an upstream adjacent channel and a downstream adjacent channel, and calibrating channel coordinates; The distributed optical fiber vibration sensing system continuously collects vibration signals of all measuring points along the pipeline at a fixed sampling frequency, and outputs original time domain data in the form of time stamp-measuring point position-vibration amplitude; Band-pass filtering is carried out on the original time domain data, extremely low frequency drift and high frequency electromagnetic interference are filtered, a frequency band related to leakage is reserved, a sliding time window mean value of a filtered signal in unit time is calculated to serve as a background baseline, the background baseline is subtracted from the original time domain data, the signal baseline drift is eliminated, and a corrected signal is obtained; Calculating short-time energy accumulation values of the corrected signals according to space segments, and judging the corrected signals as suspected leakage sections if the energy values of more than 3 continuous time windows of a certain section meet the requirements; and intercepting time domain signals of two sensing channels in the suspected leakage section to be used as signals to be analyzed.
3. The method for identifying and locating the leakage point of the pipeline based on the characteristics of the optical fiber vibration signal according to claim 1, wherein the method comprises the following steps: The judging mode of whether the geological layer type of the suspected leakage section is a non-uniform geological layer is as follows: Performing fast Fourier transform on the two-channel signal to be analyzed, and converting the time domain signal into a frequency domain signal to obtain the amplitude and the phase of each frequency component; Calculating the cross power spectrum of the two-channel signal to be analyzed, and extracting the phase value of the cross power spectrum to obtain a phase-frequency curve; And (3) performing linear fitting on the phase-frequency curve, calculating the fitting goodness, and if the fitting goodness meets the requirement, determining that the phase-frequency curve is a uniform geological layer, and otherwise, determining that the phase-frequency curve is a non-uniform geological layer.
4. The method for identifying and locating the leakage point of the pipeline based on the characteristics of the optical fiber vibration signal according to claim 1, wherein the method comprises the following steps: the time-frequency rearrangement conversion process comprises the following steps: Respectively carrying out short-time Fourier transform on the two-channel signals to be analyzed, wherein a window function is a Hanning window, the window length and the step length are set, and the amplitude and the phase corresponding to each time point-frequency point are output to form a preliminary time spectrum; and calculating local instantaneous frequency and group delay of each time-frequency point in the short-time Fourier transform result, and reallocating the spectrum energy to the real time-frequency position to obtain a high-resolution rearranged time spectrum.
5. The method for identifying and locating a pipeline leakage point based on the characteristics of an optical fiber vibration signal according to claim 4, wherein the method comprises the following steps: The instantaneous frequency main ridge line is formed in the following way: And extracting frequency components with maximum energy from the time spectrum after the time-frequency rearrangement conversion time by time along a time axis, and connecting the frequency points in time sequence to form an instantaneous frequency main ridge line.
6. The method for identifying and locating the leakage point of the pipeline based on the characteristics of the optical fiber vibration signal according to claim 1, wherein the method comprises the following steps: the nonlinear alignment process comprises the following steps: For suspected leak sections: Setting the instantaneous frequency main ridge line of one channel as a reference sequence, marking the corresponding channel as a reference channel, setting the instantaneous frequency main ridge line of the other channel as a test sequence, and marking the corresponding channel as a test channel; constructing a distance matrix of the reference sequence and the test sequence by adopting Euclidean distance, and calculating a frequency difference value of a corresponding time point; and searching a path with the smallest accumulated distance from the distance matrix by adopting a dynamic time warping algorithm, namely an optimal regular path, and outputting the optimal regular path and the accumulated distance of the time mapping relation.
7. The method for identifying and locating a pipeline leakage point based on the characteristics of an optical fiber vibration signal according to claim 6, wherein the method comprises the following steps: The method for reconstructing the original time domain signal comprises the following steps: extracting a time mapping relation of the optimal regular path, namely, a time point of each time point of the test channel corresponding to the reference channel, and for each time point of the reference channel and the test channel in the optimal regular path: if the time point of the test channel is less than the time point of the reference channel, the signal of the test channel is lagged, and the signal compression is carried out on the test channel, namely the amplitude values of the adjacent time points are combined; if the test channel time point is greater than the reference channel time point, the test channel signal is advanced, and the test channel is subjected to signal stretching, namely the difference value is supplemented with amplitude; and outputting a distortion correction reconstruction signal of the test channel, and accurately aligning the distortion correction reconstruction signal with the original signal of the reference channel on a time axis.
8. The method for identifying and locating a pipeline leakage point based on the characteristics of an optical fiber vibration signal according to claim 7, wherein the method comprises the following steps: the extraction mode of the effective time delay difference is as follows: Performing cross-correlation operation on the original signal of the reference channel and the reconstructed signal of the test channel to obtain a cross-correlation function curve; extracting a time difference corresponding to the peak value of the curve, namely, a time delay difference of a leakage signal transmitted from a leakage point to a reference channel and a test channel; if a plurality of peaks exist in the cross-correlation curve, a peak with the largest amplitude and the narrowest width is selected as an effective peak.
9. The method for identifying and locating the leakage point of the pipeline based on the characteristics of the optical fiber vibration signal according to claim 1, wherein the method comprises the following steps: The calculation mode of the leakage point space position is as follows: Taking the wave speed given by the geological survey report as an initial value, and dynamically calibrating the reference wave speed by combining the pipeline operating pressure and the soil moisture content; And calculating the distance difference from the double channels to the leakage points according to the effective time delay difference, and solving the space coordinates of the leakage points by a hyperbolic positioning method by combining the channel coordinates and the GIS data of the pipeline.
10. The method for identifying and locating a pipeline leakage point based on the characteristics of an optical fiber vibration signal according to claim 9, wherein the method comprises the following steps: the identification mode of the leakage type is as follows: Setting a first cumulative distance threshold and a second cumulative distance threshold based on the historical leakage data; If the accumulated distance is smaller than the first threshold value of the accumulated distance and the local extension of the regular path is smaller than the set value, judging that the holes leak; If the accumulated distance is greater than the accumulated distance second threshold value and the local expansion and contraction of the regular path is greater than the set value, judging that the crack leaks; if the accumulated distance is between the first accumulated distance threshold and the second accumulated distance threshold, the micro leakage or suspected leakage is judged.

Description

Pipeline leakage point identification and positioning method based on optical fiber vibration signal characteristics Technical Field The invention relates to the technical field of optical fiber sensing and pipeline safety monitoring, in particular to a pipeline leakage point identification and positioning method based on optical fiber vibration signal characteristics. Background With the acceleration of the urban process and the rapid development of industry, the pipeline is used as a core infrastructure for water resource transportation and energy transmission, and the safe and stable operation of the pipeline is very important. However, the pipeline is affected by factors such as geological sedimentation, corrosion, external impact and the like in the long-term use process. At present, the pipeline leakage monitoring technology based on optical fiber vibration sensing is widely applied due to the advantages of high sensitivity, long-distance monitoring, electromagnetic interference resistance and the like. However, in actual engineering scenes, particularly in non-uniform geological layers (such as clay-sand interlayers and miscellaneous earth filling areas), the technology faces a plurality of challenges, namely that firstly, the propagation speeds of vibration waves with different frequencies in the non-uniform geological layers are different, so that a signal has a dispersion effect, a phase-frequency relationship is nonlinear, a conventional monitoring method does not process the problem, so that signal characteristics are extracted and distorted, secondly, the non-uniform geological layers cause a two-channel signal to generate nonlinear time distortion and waveform dislocation, the time delay difference error extracted by directly adopting cross-correlation analysis is large, the positioning accuracy of leakage points is low, thirdly, the hole leakage, crack leakage and micro leakage are difficult to distinguish by the conventional method, a targeted repair basis cannot be provided for operation and maintenance, and fourthly, the energy anomaly threshold and the accumulated distance threshold are set to lack of suitability with the actual working conditions on site, and false alarm and missing alarm are easy to occur. Therefore, the invention provides a method for identifying and positioning the pipeline leakage point based on the characteristics of the optical fiber vibration signal. Disclosure of Invention The invention aims to provide a method for identifying and positioning a pipeline leakage point based on optical fiber vibration signal characteristics so as to solve the background problem. The invention aims at realizing the technical scheme that the method for identifying and positioning the pipeline leakage point based on the characteristics of the optical fiber vibration signal comprises the following steps: Collecting vibration signals along the pipeline through a distributed optical fiber vibration sensing system, identifying a suspected leakage section based on energy abnormal characteristics, and intercepting time domain signals of two adjacent sensing channels in the suspected leakage section as signals to be analyzed of double channels; performing frequency dispersion characteristic analysis on the two-channel signal to be analyzed, and judging whether the geological layer type of the suspected leakage section is a non-uniform geological layer or not through linear analysis on a cross power spectrum phase-frequency curve; If yes, carrying out time-frequency rearrangement conversion on the two-channel signal to be analyzed, extracting a high-resolution time spectrum, and acquiring a frequency component connecting line with the maximum energy along a time axis to form an instantaneous frequency main ridge line; Taking one channel main ridge line as a reference, adopting a dynamic time warping algorithm to carry out nonlinear alignment on the other channel main ridge line to obtain an optimal warping path and an accumulated distance, reconstructing an original time domain signal according to the optimal warping path, and extracting an effective time delay difference; And calculating the spatial position of the leakage point by a hyperbolic positioning method by combining the dynamically calibrated reference wave speed and the effective time delay difference, and identifying the leakage type according to the accumulated distance and the local expansion and contraction characteristics of the optimal regular path. Further, the suspected leakage section is identified in the following manner: dividing the distributed optical fiber into a plurality of continuous measuring point groups along the axial direction of the pipeline, wherein each group is a sensing channel, selecting an upstream adjacent channel and a downstream adjacent channel, and calibrating channel coordinates; The distributed optical fiber vibration sensing system continuously collects vibration signals of all measuring points