Gas pipeline leakage analogue simulation platform and multi-field traceability positioning system

Abstract

The invention discloses a gas pipeline leakage analogue simulation platform and a multi-field traceability positioning system, and relates to the technical field of gas pipeline full-process monitoring and leakage early warning. The platform comprises a gas pipeline leakage similar physical simulation experiment platform, a suspended gas pipeline leakage multi-field traceability positioning system and a buried gas pipeline leakage multi-field traceability positioning system. The experiment platform reproduces real working conditions through an air source generating and conveying module, a multi-burial-depth adjustable inspection well vertical shunting structure and a complete air source processing system; the suspended system is based on strain field and sound wave field dual-field cooperative monitoring; the buried system is based on multi-field cooperative monitoring of a sound wave field, a geoelectric field, a strain field and a temperature field. According to the invention, through cooperative arrangement of multiple sensors, multi-field data fusion processing and traceability positioning, precise identification and high-precision positioning of gas leakage are realized, and the method is suitable for safety monitoring and intelligent early warning of gas pipelines under complex working conditions.

Description

Technical Field

[0001] This invention relates to the field of gas pipeline full-process monitoring and leakage early warning technology, and more specifically to a gas pipeline leakage simulation platform and a multi-field source tracing and positioning system. Background Technology

[0002] Currently, the aging and wear and tear of pipeline facilities and sudden failures under complex operating conditions have made the safety assessment, hidden danger investigation and precise maintenance of gas pipelines a major social problem that urgently needs to be solved in urban safety governance, which is directly related to urban public safety and sustainable development.

[0003] However, there are still significant shortcomings in the existing physical simulation experimental platforms for urban gas pipeline networks: most existing platforms are small-scale laboratory devices, generally less than 1 / 50 the size of actual pipeline networks, making it difficult to reproduce real operation and maintenance scenarios such as pressure gradients, airflow states, and multiple leakage points in long-distance pipeline networks; at the same time, the experimental conditions are designed in a single way, lacking simulation of actual influencing factors such as complex geological environments, extreme weather, and construction disturbances, resulting in a large deviation between experimental results and actual engineering, and failing to provide reliable data support for the research and development of leakage monitoring technology and the formulation of prevention and control solutions.

[0004] Different types of pipelines have significantly different structural characteristics and operating conditions. Existing monitoring systems lack targeted adaptation designs, making it difficult to form a closed-loop management system of "comprehensive perception, accurate early warning, and intelligent decision-making," and thus failing to meet the actual needs of safe operation and maintenance of urban gas pipelines.

[0005] Therefore, how to construct a gas pipeline leakage simulation platform that can reproduce real working conditions, and how to achieve accurate replication of leakage mechanisms, effective verification of monitoring technologies, and rapid and accurate location of leakage points are problems that urgently need to be solved by those skilled in the art. Summary of the Invention

[0006] In view of the above problems, the present invention is proposed to provide a gas pipeline leakage simulation platform and a multi-field source tracing and positioning system that overcomes or at least partially solves the above problems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A gas pipeline leakage simulation platform includes a gas source generation and collection module and a gas source transportation module, as well as a near-end manhole and a far-end manhole for simulating gas pipeline leakage experiments under different burial depth conditions.

[0008] The air source generation and collection module includes an air compressor, an air tank, a refrigerated dryer, and a filter, which are connected sequentially via pipelines and hoses.

[0009] The gas supply module includes a pressure reducing valve, an inlet pressure sensor, an inlet flow sensor, a manhole vertical diversion steel pipe, a manhole connecting steel pipe, a leak point test steel pipe, an outlet flow sensor, an outlet pressure sensor, and a venting valve; a leak point test steel pipe is installed between the two manhole connecting steel pipes, and a leak point solenoid ball valve assembly is installed on the leak point test steel pipe; the gas supply module is connected to the filter of the gas source generation and gas collection module through the pressure reducing valve; The pressure reducing valve, the air inlet pressure sensor, and the air inlet flow sensor are connected in sequence and then connected to the manhole vertical diversion steel pipe in the near end of the manhole via a quick-connect hose. The outlet flow sensor, outlet pressure sensor, and vent valve are connected in sequence and then connected to the manhole vertical diversion steel pipe in the far end manhole via a quick-connect hose.

[0010] Preferably, the vertical diversion steel pipe in the near-end or far-end manhole is provided with branch holes at intervals along the axial direction, and each branch hole is connected by a manhole connecting steel pipe.

[0011] This invention provides a multi-field source tracing and location system for gas pipeline leaks. Based on a gas pipeline leak simulation platform, the source tracing and location system includes a suspended gas pipeline area module and a buried gas pipeline area module, which are deployed on the gas pipeline leak simulation platform.

[0012] The suspended gas pipeline area module involves the suspended strain field and the suspended sound wave field, while the buried gas pipeline area module involves the buried sound wave field, the buried geoelectric field, and the buried strain-temperature field.

[0013] The suspended gas pipeline area module includes a suspended strain field monitoring unit, a suspended acoustic wave field monitoring unit, a suspended data processing unit, and a suspended spatial positioning unit.

[0014] The buried gas pipeline area module includes a buried acoustic field testing unit, a buried geoelectric field testing unit, a buried strain-temperature field testing unit, and a buried data collaborative processing unit.

[0015] Preferably, the specific content of the suspended gas pipeline area module is as follows: The suspended strain field monitoring unit uses fiber optic grating sensors, which are deployed on the test steel pipe at the leak point using a uniform or dense arrangement method to collect suspended strain field monitoring data. The suspended acoustic field monitoring unit uses a unidirectional or tridirectional accelerometer sensor, which is deployed at the same point as the fiber optic grating sensor for the suspended strain field to collect suspended acoustic field monitoring data. The suspended data processing unit preprocesses, extracts, and fuses features from suspended strain field monitoring data and suspended acoustic wave field monitoring data, and outputs the identification results of the suspended gas pipeline leak point. The suspended space positioning unit, based on the identification results of the suspended gas pipeline leak point output by the suspended data processing unit, performs accurate positioning through a time difference positioning algorithm and outputs the distance between the leak point location and the sensor location.

[0016] Preferably, the specific content of the buried gas pipeline area module is as follows: The buried acoustic field test unit uses low-frequency seismic wave detectors arranged in a cross-shaped array structure to collect buried acoustic field test data. The buried electric field testing unit uses non-polarized electrodes arranged in a high-density grid structure to collect buried electric field test data. The buried strain-temperature field testing unit uses tight-buffered and loose-buffered optical cables arranged in a three-dimensional sensor network structure to collect buried strain-temperature field test data within the monitoring range of buried acoustic wave field and buried geoelectric field. The buried data collaborative processing unit performs preprocessing, feature extraction, fusion analysis, and three-dimensional source tracing and positioning operations on buried acoustic field test data, buried geoelectric field test data, and buried strain-temperature field test data, and outputs the three-dimensional coordinates of the leak point.

[0017] Preferably, the sensitive axis of the unidirectional accelerometer in the suspended acoustic field monitoring unit is aligned with the axial direction of the steel pipe used for leak point testing, while the sensitive axis of the tridirectional accelerometer covers the axial, radial horizontal, and radial vertical directions of the steel pipe used for leak point testing.

[0018] Preferably, the suspended data processing unit includes a suspended strain data preprocessing module, a suspended acoustic wave data preprocessing module, a suspended feature extraction module, and a suspended feature fusion module; The suspended strain data preprocessing module performs temperature compensation and baseline correction on the suspended strain field monitoring data. The suspended acoustic wave data preprocessing module performs frequency band filtering, adaptive noise reduction, and signal normalization on the suspended acoustic wave field monitoring data. The suspended feature extraction module is used to extract the dynamic and spatial features of the preprocessed suspended strain field monitoring data, and to extract the time-domain, frequency-domain, and spatial propagation features of the preprocessed suspended acoustic wave field data. The suspended feature fusion module is used for spatiotemporal matching, weight assignment, and spatial fusion positioning of suspended strain field and suspended acoustic wave field to generate identification results of leak points in suspended gas pipelines.

[0019] Preferably, the buried data collaborative processing unit includes a buried multi-field data preprocessing module, a buried feature extraction module, a buried fusion analysis module, and a buried three-dimensional tracing and positioning module; The buried multi-field data preprocessing module performs preprocessing operations such as synchronous correction, filtering and noise reduction, and signal normalization on buried acoustic field test data; polarization drift compensation, grounding resistance correction, background field subtraction, and resistivity conversion on buried geoelectric field test data; and coupling signal separation, spatial interpolation completion, and baseline update on buried strain-temperature field test data.

[0020] The buried feature extraction module is used to extract the time-domain, frequency-domain, and spatial features of the buried acoustic field, buried geoelectric field, and buried strain-temperature field.

[0021] The buried feature fusion analysis module, based on the fusion logic of spatiotemporal matching, weight adaptation, and conflict resolution, calculates the fusion confidence of the features output by the buried feature extraction module.

[0022] Leakage is determined based on the fusion confidence level and the preset leakage discrimination strategy, and a gas leakage judgment result is generated.

[0023] The buried 3D source tracing and positioning module combines the gas leak judgment results with buried acoustic wave field test data, buried geoelectric field test data, and buried strain-temperature field test data to output the 3D positioning coordinates of the buried gas pipeline leak point.

[0024] The preferred method for calculating fusion confidence is as follows: Fusion confidence = Σ (single-source anomaly probability × corresponding weight); Among them, the anomaly probability of a single source is the anomaly probability of any one of the physical fields among the buried acoustic field, the buried geoelectric field, and the strain-temperature field.

[0025] Preferably, the time difference positioning algorithm formula used in the suspended space positioning unit is: ; In the formula, and For different receiving times, and These are the coordinates of the point. For the speed of sound wave propagation, This refers to the distance between the output leak point location and the sensor location.

[0026] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a gas pipeline leakage simulation platform and a multi-field source tracing and positioning system. The beneficial effects of the above technical solutions provided by the embodiments of the present invention include at least the following: 1. The simulation platform has high fidelity and strong adaptability, breaking through the limitations of existing miniaturized experimental platforms, and can accurately replicate real operation and maintenance scenarios such as pressure gradient and airflow status of long-distance gas pipelines.

[0027] 2. The monitoring system is highly targeted and covers all dimensions. It can design adaptation schemes for the structural differences between suspended and buried pipelines, achieving full planar coverage and vertical layered three-dimensional perception around the leak point, and completely solving the problems of high false alarm rate and poor adaptability to complex environments of single monitoring dimensions.

[0028] 3. Integrating high positioning accuracy and reliability, innovative research and development of preprocessing, feature extraction, collaborative fusion, and precise source tracing data processing technologies, through spatiotemporal matching verification, weighted adaptive fusion, etc., effectively eliminates environmental interference and improves the accuracy of leak identification. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0030] Figure 1 This is a construction scheme for a physical simulation experimental platform for gas pipeline leakage provided in this embodiment of the invention; Figure 2 This is the layout scheme of the suspended gas pipeline sensing system provided in the embodiments of the present invention; Figure 3 This is the deployment scheme for the buried gas pipeline sensing system provided in this embodiment of the invention; Figure 4 The suspended gas pipeline provided in this embodiment of the invention does not leak its own frequency domain signal characteristics in each direction; Figure 5 The frequency domain signal response characteristics of the suspended gas pipeline sensor #1 provided in this embodiment of the invention; Figure 6 The frequency domain signal response characteristics of the suspended gas pipeline sensor #2 provided in this embodiment of the invention; Figure 7 The frequency domain signal response characteristics of the suspended gas pipeline sensor #3 provided in this embodiment of the invention; Figure 8 The suspended gas pipeline #4 provided in this embodiment of the invention z Characteristics of the sensor's frequency domain signal response; Figure 9 The suspended gas pipeline #5 provided in this embodiment of the invention zCharacteristics of the sensor's frequency domain signal response; Figure 10 The frequency domain signal response characteristics of the suspended gas pipeline 4#x sensor provided in this embodiment of the invention; Figure 11 The suspended gas pipeline #5 provided in this embodiment of the invention x Characteristics of the sensor's frequency domain signal response; Figure 12 The suspended gas pipeline #4 provided in this embodiment of the invention y Characteristics of the sensor's frequency domain signal response; Figure 13 The suspended gas pipeline #5 provided in this embodiment of the invention y Characteristics of the sensor's frequency domain signal response; Figure 14 This is a graph showing the wavelength change of a fiber optic grating during a 0.4MPa pressure leak in a suspended gas pipeline, as provided in an embodiment of the present invention.

[0031] Figure 1 In the middle, 1-air compressor, 2-air tank, 3-filter, 4-pipeline connecting hose, 5-pressure reducing valve, 6-refrigerated dryer, 7-inlet pressure sensor, 8-inlet flow sensor, 9-manhole quick-connect hose, 10-manhole vertical diversion steel pipe, 11-manhole connecting steel pipe, 12-leakage point electromagnetic ball valve assembly, 13-leakage point test steel pipe, 14-outlet flow sensor, 15-outlet pressure sensor, 16-venting valve. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] like Figure 1 As shown in the figure, this embodiment of the invention discloses a gas pipeline leakage simulation platform, including a gas source generation and gas collection module and a gas source transportation module, and also includes a near-end manhole and a far-end manhole for simulating gas pipeline leakage experiments under different burial depth conditions.

[0034] The air source generation and collection module includes an air compressor 1, an air tank 2, a refrigerated dryer 6, and a filter 3, which are connected sequentially via pipelines and hoses 4. The gas source delivery module includes a pressure reducing valve 5, an inlet pressure sensor 7, an inlet flow sensor 8, a manhole vertical diversion steel pipe 10, a manhole connecting steel pipe 11, a leak point testing steel pipe 13, an outlet flow sensor 14, an outlet pressure sensor 15, and a venting valve 16; a leak point testing steel pipe 13 is installed between the two manhole connecting steel pipes 11, and a leak point electromagnetic ball valve assembly 12 is installed on the leak point testing steel pipe 13; the gas source delivery module is connected to the filter 3 of the gas source generation and gas collection module through the pressure reducing valve 5; The pressure reducing valve 5, the air inlet pressure sensor 7, and the air inlet flow sensor 8 are connected in sequence and then connected to the manhole vertical diversion steel pipe 10 in the near end of the manhole through the manhole quick-connect hose 9. The outlet flow sensor 14, outlet pressure sensor 15, and vent valve 16 are connected in sequence and then connected to the manhole vertical diversion steel pipe 10 in the remote manhole through the manhole quick-connect hose 9.

[0035] Specifically, this invention provides specific requirements for a simulation platform, as follows: A gas storage tank uses 1m 3 The gas storage capacity is 0.8 MPa. The steel pipe buried in the soil is a seamless steel pipe with an outer diameter of 108 mm and an inner diameter of 100 mm. The manhole diameter is 800 mm, the manhole cover size is 700 mm, and the depth is 2.2 m. The sides and bottom are treated with brick and concrete structure. There are 4 branch holes at 0.5 m above the ground. The 4 branch holes are set vertically along the inner wall of the manhole's vertical diversion steel pipe from top to bottom with a spacing of 0.5 m. The manhole spacing is 8 m, and the reserved holes are symmetrically arranged to install a ladder to the manhole. The pipe connection between the two manhole covers is a quick-connect hose.

[0036] This invention provides a multi-field source tracing and location system for leaks in suspended gas pipelines based on the aforementioned simulation platform. The system includes a suspended gas pipeline area module and a buried gas pipeline area module, both deployed on the gas pipeline leak simulation platform. The suspended gas pipeline area module involves suspended strain and suspended acoustic fields, while the buried gas pipeline area module involves buried acoustic fields, buried geoelectric fields, and buried strain-temperature fields. The suspended gas pipeline area module includes a suspended strain field monitoring unit, a suspended acoustic field monitoring unit, a suspended data processing unit, and a suspended spatial positioning unit. The buried gas pipeline area module includes a buried acoustic field testing unit, a buried geoelectric field testing unit, a buried strain-temperature field testing unit, and a buried data collaborative processing unit.

[0037] like Figure 2 As shown, it specifically includes: a suspended strain field monitoring unit using fiber optic grating sensors and a suspended acoustic wave field monitoring unit using unidirectional / tridirectional accelerometers.

[0038] Since the core requirement of the suspended strain field monitoring unit is to capture minute strain changes and achieve long-term stable monitoring, the fiber optic grating sensor has ultra-high strain measurement accuracy and can accurately respond to the minute deformation of the test object. The fiber optic grating sensor is resistant to electromagnetic interference, has a wide temperature range, can adapt to complex test environments, avoids the impact of external interference on data accuracy, and supports distributed measurement, which can simultaneously acquire strain information from multiple test points and improve test efficiency.

[0039] Since the suspended acoustic wave field monitoring unit needs to capture vibration response signals in different directions, the unidirectional accelerometer is designed for the sound wave propagation path in a specific direction, with high sensitivity and wide frequency response range, and can accurately collect single-dimensional acoustic wave vibration data; the triaxial accelerometer can simultaneously acquire vibration information in three orthogonal directions of X, Y and Z, adapting to the full-space distribution testing requirements of complex acoustic wave fields, realizing all-round characterization of sound wave propagation direction and intensity, and making up for the dimensional limitations of the unidirectional sensor.

[0040] Furthermore, the construction of a multi-site source tracing and location system for leaks in suspended gas pipelines specifically includes the following: The suspended strain field monitoring unit, equipped with fiber optic grating sensors, is deployed along the entire axial length of the gas pipeline, using a uniform deployment plus key densification mode: in ordinary pipe sections, individual fiber optic grating sensors are deployed at intervals of 5 to 10 meters, forming a distributed strain monitoring chain in series; in high-risk pipe sections involving pipe joints, welds, historically corroded sections, buried-to-overhead / crossing sections, or within 3 meters on both sides of valves, the fiber optic grating sensors are deployed at intervals of 1 to 2 meters, and at least two orthogonal fiber optic grating sensors are deployed at each high-risk point to capture the dual strain of radial expansion and axial tension caused by leakage.

[0041] Furthermore, the fiber optic grating sensor is installed using a minimally invasive bonding method. Specifically, the coating on the pipe surface is cleaned, and the bare grating section of the sensor is bonded to the surface of the gas pipe using a high-temperature resistant and gas corrosion resistant epoxy adhesive. The outside is covered with a stainless steel protective sheet with a thickness of ≤1mm to avoid damage from soil friction and external impact, while ensuring efficient transmission of strain signals.

[0042] Furthermore, the gas pipeline is divided into monitoring zones every 1-2 km. Each zone is equipped with a fiber optic grating sensor string. Zones are connected through fiber optic fusion splices. The terminal is connected to a fiber optic grating demodulator with a demodulation accuracy of ≤1 pm to complete the initial positioning of strain anomaly points within ±1 m.

[0043] Furthermore, the suspended acoustic field monitoring unit is equipped with unidirectional / tridirectional accelerometers. The unidirectional accelerometers are mainly deployed along the axial direction of the gas pipeline, at the same locations as the fiber optic grating sensors. Ordinary gas pipeline sections correspond one-to-one with the fiber optic grating sensors in the suspended strain field monitoring unit. High-risk gas pipeline sections are also densified with the suspended strain field fiber optic grating sensors to 1-2m. The sensitive axis of the unidirectional accelerometer is consistent with the axial direction of the gas pipeline, accurately capturing the propagation signal of the leakage sound wave along the pipeline axis. The tridirectional accelerometers are deployed at key nodes of the gas pipeline, such as valve wells, pressure reducing valve groups, pipeline bends, buried / overhead transition sections, and midpoints of long-distance pipeline sections. One tridirectional accelerometer is deployed at each node. The sensitive axis of the tridirectional accelerometer covers three directions: the X-axis parallel to the pipeline, the Y-axis perpendicular to the pipeline in the horizontal plane, and the Z-axis perpendicular to the pipeline in the vertical plane. This is used to capture the multidirectional propagation components of the leakage sound wave under complex terrain, compensating for the directional limitations of the unidirectional accelerometer.

[0044] Furthermore, the unidirectional / tridirectional accelerometer adopts a magnetic design, which can automatically couple with ferrous gas pipelines; for non-ferrous gas pipelines, the sensor base is fastened to the surface of the gas pipeline by an arc-shaped metal clamp, and the gap between the unidirectional / tridirectional accelerometer and the surface of the gas pipeline is ≤0.1mm. It is coupled with the gas pipeline by mechanical clamping and sealing protection.

[0045] By deploying fiber optic grating sensors and unidirectional accelerometers in the same direction along the gas pipeline axis, a dual-feature monitoring point of suspended strain field and suspended acoustic wave field is formed. When both strain anomaly and acoustic wave anomaly are detected at a certain point, the location algorithm is triggered, improving the accuracy of leak point identification.

[0046] The data preprocessing process for the multi-site source tracing and location system for leaks in suspended gas pipelines includes the following: The preprocessing of strain data from fiber Bragg grating sensors includes temperature compensation and baseline correction.

[0047] Temperature compensation: The dual-grating differential method is adopted, which utilizes the wavelength difference between the temperature-sensitive grating and the strain-sensitive grating packaged at the same location to eliminate temperature drift interference within the operating temperature range of 40℃~80℃. Baseline correction: Based on the pipeline's leak-free steady-state condition, establish the strain baseline value of each sensing unit, and subtract the baseline value from the real-time data to eliminate static strain interferences such as the pipeline's thermal expansion and contraction and long-term creep.

[0048] The preprocessing of acoustic wave data from unidirectional / tridirectional accelerometers includes frequency band filtering, adaptive noise reduction, and signal normalization.

[0049] Frequency band selection: Extract effective acoustic frequency band data through a 10Hz~10kHz bandpass filter.

[0050] Adaptive noise reduction: The wavelet threshold noise reduction algorithm is used to identify and eliminate instantaneous pulse interference such as valve switching vibration and vehicle passing, while preserving the continuous vibration characteristics of the leakage sound wave.

[0051] Signal normalization: The output voltage signals of unidirectional / tridirectional accelerometers with different sensitivities are uniformly converted into vibration acceleration values, eliminating the data magnitude deviation caused by individual differences in unidirectional / tridirectional accelerometers, and laying the foundation for cross-point comparison.

[0052] The feature extraction process in the multi-site source tracing and localization system for leaks in suspended gas pipelines includes the following: The features extraction of suspended strain fields includes dynamic feature extraction and spatial feature extraction.

[0053] Dynamic feature extraction: Extract the three-dimensional features of strain data: "abrupt amplitude-duration-rate of change". The strain anomalies caused by feature extraction leakage must meet the following requirements: axial strain abrupt change amplitude ≥ ±5με, circumferential strain abrupt change amplitude ≥ ±3με, and anomaly duration ≥ 10s, strain change rate ≥ 0.5με / s.

[0054] Spatial feature extraction: Identify continuous distribution segments of strain anomalies, with leak points corresponding to "localized concentrated anomalies" rather than uniform strain changes along the entire pipeline length, while also recording the axial position of the anomaly segment.

[0055] The features extraction of suspended acoustic wave fields include time-domain feature extraction, frequency-domain feature extraction, and spatial propagation feature extraction.

[0056] Temporal feature extraction: Extract the peak acceleration (≥0.01g during leakage, much higher than ≤0.002g of environmental vibration) and pulse period of the acoustic signal (the leakage acoustic wave is a continuous vibration with a period of ≤0.1s, which is different from the single pulse of valve switching).

[0057] Frequency domain feature extraction: The time domain signal is converted into a frequency domain spectrum by fast Fourier transform, and the main frequency peak is extracted (the main frequency of gas leakage sound wave is concentrated in 200Hz~5kHz, and there are 2~3 harmonics). At the same time, the proportion of frequency band energy between 100Hz~1kHz is calculated. When the frequency band energy proportion is ≥60%, it is suspected to be a leak.

[0058] Spatial propagation feature extraction: The time difference of abnormal sound waves received by accelerometers at different locations with an accuracy of ≤1ms is recorded. Combined with the propagation speed of sound waves in steel gas pipelines, the spatial range of suspected leak points is preliminarily calculated.

[0059] The process of fusing suspended features in a multi-field source tracing and localization system for leaks in suspended gas pipelines includes the following: The content of suspended feature fusion includes spatiotemporal matching and weighted fusion of suspended strain field and suspended acoustic wave field.

[0060] Spatiotemporal matching: When a fiber optic grating in a certain area detects an abnormal strain, that is, meets the threshold of "abrupt amplitude - duration", and a unidirectional accelerometer within ±1m of that area simultaneously detects an acoustic signal that meets the characteristics of "dominant frequency - peak acceleration", it is judged as "suspected leakage" to avoid misjudgment of single-field data.

[0061] Weighting: Based on training with historical leakage cases, the strain field anomaly is assigned a weight of 0.6 and the acoustic field anomaly a weight of 0.4. When the combined weight of the strain field anomaly and the acoustic field anomaly is ≥0.5, a leakage alarm is triggered.

[0062] Spatial fusion positioning: First, a coarse positioning is performed using the fiber optic strain field anomaly segment as the initial positioning range, excluding acoustic interference areas without strain anomalies. Then, the time difference between the leakage acoustic waves received by three or more accelerometers within the anomaly segment is used and substituted into the time difference positioning algorithm formula: ; In the formula, and For different receiving times, and These are the coordinates of the point. For the speed of sound wave propagation, This refers to the distance between the output leak point location and the sensor location. Combined with the spatial constraints of the abnormal strain field segment, the leak point location accuracy is ultimately maintained within ±0.5m.

[0063] In another specific embodiment, the present invention provides a multi-site source tracing and location system for buried gas pipeline leaks, specifically comprising: like Figure 3 As shown in (a), (b), and (c), there are buried acoustic field testing units using low-frequency seismic detectors, buried geoelectric field testing units using non-polarized electrodes, and buried strain-temperature field testing units using distributed tight-buffered and loose-buffered optical cables.

[0064] The specific sensor deployment method for each test unit is as follows: The buried acoustic field test unit for low-frequency seismic detectors is equipped with 12 low-frequency seismic detectors along the pipeline and 12 low-frequency seismic detectors perpendicular to the pipeline, forming a total of 24 detectors to form a cross-shaped monitoring array that covers the core area around the leak.

[0065] Furthermore, the spacing between all low-frequency seismic detectors is uniformly 0.2m, the coverage area of ​​the 12 detectors in the north-south direction is 2.2m, the coverage area of ​​the 12 detectors in the east-west direction is 2.2m, and the core area of ​​the overall monitoring array is 2.2m×2.2m.

[0066] Among them, the sixth and seventh low-frequency seismic detectors, which run north-south and east-west respectively, are symmetrically distributed on both sides of the center of the leak outlet to ensure the initial capture of the leak acoustic signal and the acquisition of bidirectional propagation characteristics.

[0067] Furthermore, the low-frequency seismic detector is installed by burying it at a depth of 0.1m, with fine sand laid at the bottom to level it, ensuring that the detector is tightly coupled with the soil medium and improving the transmission efficiency of low-frequency sound waves.

[0068] Furthermore, the buried geoelectric field test unit with non-polarized electrodes has four geoelectric field measurement lines arranged parallel to the pipeline, with a line spacing of 0.2m and a total coverage width of 0.6m, which overlaps with the core area of ​​the buried acoustic wave field test unit array.

[0069] Furthermore, 16 non-polarized electrodes are evenly arranged along each measuring line, with an electrode spacing of 0.1m and a single measuring line coverage length of 1.5m. A total of 64 electrodes are arranged along the four measuring lines, forming a high-density buried geoelectric field monitoring grid.

[0070] Furthermore, the second and third measuring lines are symmetrically distributed on both sides of the center of the leak, ensuring that the underground geoelectric field anomaly caused by the leak is accurately presented in the core measuring lines.

[0071] Furthermore, the non-polarized electrode is vertically buried at a depth of 0.2m, ensuring that the bottom of the non-polarized electrode is in full contact with the soil and that the grounding resistance is ≤5kΩ, thus guaranteeing the effective acquisition of weak potential difference signals.

[0072] Furthermore, the electrodes of the four survey lines are arranged according to the "point-by-point numbering" rule, such as survey line 1-electrode 1 to survey line 4-electrode 16, to facilitate the spatial coordinate positioning of buried geoelectric field anomaly points.

[0073] Furthermore, a multi-channel ground electric field acquisition instrument with ≥64 channels and ≤0.1μV resolution is adopted, which directly matches the low output impedance of the non-polarized electrode, eliminating the need for an additional impedance conversion module.

[0074] The buried strain-temperature field detection unit for tight-buffered / unbuffered distributed optical cable deployment mainly adopts a "three-layer three-dimensional + dual optical cable synchronous" design. The three layers are deployed at the following positions: the first layer is 0.15m below the leak point, the second layer is 0.1m above the leak point, and the third layer is 0.2m above the leak point, covering a vertical range of 0.35m from the leak point.

[0075] Furthermore, each layer is simultaneously equipped with one tight-buffered optical cable for buried strain testing and one loose-buffered optical cable for buried temperature measurement. The two optical cables are laid in a cross pattern along the north-south and east-west directions, completely overlapping with the monitoring range of buried acoustic wave field and buried geoelectric field, forming a three-dimensional sensing network.

[0076] Furthermore, the optical cable laying spacing is 0.1m, and the coverage area of ​​each layer is consistent with that of the buried acoustic field monitoring array, ensuring that the spatial resolution of the buried strain signal and the buried temperature signal can match that of other field sources.

[0077] The tight-buffered optical cable of the buried strain-temperature field detection unit is fixed by bonding with the soil or pipeline surface through epoxy adhesive, with a strain transfer coefficient ≥0.95; the loose-buffered optical cable of the buried strain-temperature field detection unit is laid loosely to ensure that a small space is reserved for movement and to avoid strain interference with temperature measurement.

[0078] Furthermore, the tight-buffered optical cables of all strain-temperature field detection units are connected in series to the BOTDA distributed strain demodulator, which has a resolution of ≤1m and a strain accuracy of ±1με. The loose-buffered optical cables of all strain-temperature field detection units are connected in series to the DTS distributed temperature measuring instrument, which has a spatial resolution of ≤1m and a temperature measuring accuracy of ±0.5℃.

[0079] Furthermore, the two distributed demodulators are linked with the buried acoustic field and buried geoelectric field acquisition systems through a time synchronization module with a synchronization error of ≤1ms, to achieve synchronous acquisition and storage of data from the four fields, providing time-consistent raw data for multi-field fusion analysis.

[0080] The data preprocessing process for the multi-site source tracing and location system for buried gas pipeline leaks includes the following: The preprocessing of acoustic wave data from low-frequency seismic detectors includes synchronization correction, filtering and noise reduction, and signal normalization.

[0081] Synchronization correction: Using the trigger record of the time synchronization module, the data from the 24 low-frequency seismic detectors are time-aligned to correct the acquisition time difference of up to ±1ms, ensuring the accuracy of the sound wave propagation time difference calculation.

[0082] Filtering and denoising: A bandpass filter matching the working frequency band of the low-frequency seismic detector, involving 1Hz~1000Hz, is used to filter out low-frequency interference from soil settlement and high-frequency electromagnetic noise. Combined with wavelet thresholding algorithm, instantaneous pulse interference such as vehicle passing and mechanical vibration is eliminated. The signal-to-noise ratio after denoising is ≥25dB.

[0083] Signal normalization: The output signals of the 24 low-frequency seismic detectors are uniformly converted into vibration velocity values, eliminating amplitude deviations caused by individual sensor differences and adapting to the spatial comparison requirements of the cross array.

[0084] The feature extraction process in the multi-site source tracing and location system for buried gas pipeline leaks includes the following: The features extracted from buried acoustic fields include time-domain features, spatiotemporal propagation features, and array response features.

[0085] Temporal feature extraction: The peak vibration velocity of 24 low-frequency seismic detectors was extracted, mainly ≥0.001m / s during leakage, which is far greater than ≤0.0002m / s of environmental noise. The extracted signal duration was ≥5s, which distinguishes it from transient interference.

[0086] Spatiotemporal propagation characteristics: The arrival time difference of the acoustic waves of the north-south and east-west low-frequency seismic detector arrays is calculated to be ≤0.1ms. Combined with the low-frequency electronic detector spacing of 0.2m, the acoustic wave propagation direction and attenuation law are fitted to pinpoint the initial region of the leaked acoustic wave.

[0087] Array response characteristics: Extract the percentage of abnormal channels in the cross array. For example, if ≥30% of the channels are detected as abnormal during leakage, that is, ≥7 detectors, this can be used as a preliminary basis for leakage judgment.

[0088] The buried gas pipeline leak multi-site source tracing and location system includes the following buried fusion analysis process: The buried fusion analysis innovatively designs a three-layer fusion logic of "spatiotemporal matching - weight adaptation - conflict adjudication" to achieve deep collaboration of multi-source data and improve the accuracy of leakage identification. Spatiotemporal matching: This includes time matching and spatial matching. It is the premise and foundation of feature fusion. The purpose is to unify buried features from different sources, different collection times, and different spatial locations into the same spatiotemporal coordinate system, ensuring that the features participating in the fusion are valid data for the same monitoring object and the same spatiotemporal range.

[0089] Time matching: When an abnormal feature is detected by a certain field source, the synchronous verification of the other three field sources is triggered. The time difference of the abnormal signal is required to be ≤0.5s, that is, it matches the multi-field synchronous response characteristics caused by leakage. Otherwise, it is judged as a single environmental interference.

[0090] Spatial matching: Based on the anomalous region of the buried acoustic field cross array, the anomalous grid of the buried geoelectric field high-density grid, and the layered anomalous range of the buried strain-temperature field, the spatial overlap rate of the three is required to be ≥70% to lock the core influence area of ​​the leak.

[0091] Adaptive weighting: This is the core weighting step in feature fusion. The key is to dynamically allocate fusion weights based on the real-time credibility of features from different sources, avoiding fusion bias caused by a fixed weight that is applied in a "one-size-fits-all" manner.

[0092] Fusion confidence calculation: Fusion confidence = Σ (single source anomaly probability × corresponding weight); Among them, the anomaly probability of a single source is the anomaly probability of any one of the physical fields among the buried acoustic field, the buried geoelectric field, and the strain-temperature field.

[0093] A confidence level ≥ 0.7 indicates a confirmed leak, a confidence level between 0.5 and 0.7 indicates a suspected leak, and a confidence level < 0.5 indicates an interference signal. The identification accuracy is ≥ 98%.

[0094] When an anomaly is detected by one or two field sources and the remaining field sources do not respond, a 30-second delay review is initiated, and historical data is compared to rule out occasional interference.

[0095] Conflict resolution: This is the correction and safeguard step for feature fusion, used to resolve contradictions or inconsistencies between multi-source features. When the anomaly spaces of multiple sources do not overlap, the fusion confidence is recalculated using a distance weighting method that assigns higher weights to those closer to the leak point, thus avoiding misjudgments of non-leakage anomalies.

[0096] The buried three-dimensional source tracing and location process in the multi-site source tracing and location system for buried gas pipeline leaks includes the following: The buried three-dimensional tracing and positioning technology includes planar positioning algorithms and vertical depth constraints.

[0097] Planar positioning algorithms also include buried acoustic time difference positioning algorithm, buried geoelectric field dual-parameter positioning algorithm, and buried planar fusion positioning algorithm.

[0098] Buried acoustic time difference positioning algorithm: Based on the time difference of arrival of acoustic waves from a cross-shaped array of 24 low-frequency seismic detectors, and substituting the propagation speed of acoustic waves in the soil, a multi-source time difference iterative algorithm is used to initially lock the plane positioning error within ±0.1m.

[0099] The buried geoelectric field dual-parameter positioning algorithm utilizes the resistivity extrema and current density distribution center of the high-density electrode grid, combined with the symmetrical characteristics of the second and third survey lines, to correct the planar positioning results with errors within ±0.08m.

[0100] Buried Plane Fusion Positioning Algorithm: The results of the buried acoustic time difference positioning algorithm and the buried geoelectric field dual-parameter positioning algorithm are weighted and fused in a 1:1 ratio, and the final output is the buried plane positioning accuracy within the range of ±0.05m.

[0101] Vertical depth constraint: Based on the strain-temperature anomaly characteristics of the three-layer optical cable, the peak position of the anomaly amplitude of each layer is extracted: the strain amplitude is ≥ ±7με and the temperature amplitude is ≥ ±1.2℃ at 0.15m below the leak. The anomaly amplitude of the two upper layers decreases with increasing distance, forming the peak characteristics of the bottom layer.

[0102] Furthermore, a mapping model between vertical depth and abnormal amplitude was established. By using the attenuation coefficients of the three-layer abnormal amplitude, the vertical depth of the leak was calculated, with a positioning accuracy within ±0.03m.

[0103] Finally, a three-dimensional source tracing output is performed. By integrating the X-axis and Y-axis planar positioning coordinates with the Z-axis vertical depth, the three-dimensional coordinates of the leak point with an accuracy within ±0.05m are output. At the same time, a multi-source fusion confidence score of ≥0.7 is marked to provide accurate basis for subsequent handling.

[0104] This invention also provides a simulation experimental platform for a multi-field source tracing and location system for gas pipeline leaks, taking suspended gas pipelines as an example, as well as a simulation experiment of a multi-field source tracing and location system for leaks in suspended gas pipelines.

[0105] The physical simulation experimental platform for a multi-field source tracing and location system for gas pipeline leaks is shown below. Figure 4 As shown, this system fills a gap in the study of gas pipeline leakage property characteristics under large-scale conditions. It mainly consists of two modules: a gas source generation and collection module, and a gas source delivery module. The main instrument parameters are shown in Table 1. Table 1. Physical components and parameters of the similar physical simulation experimental platform for gas pipeline leakage.

[0106] A simulation experiment of a multi-field source tracing and location system for leaks in suspended gas pipelines was conducted. This involved opening a leak in the middle of an existing pipeline on an experimental platform and controlling the opening and closing of the leak point with a solenoid valve. The experiment was conducted as follows: the leak diameter was 10 mm, and the gas pressure inside the pipe increased from 0.1 MPa to 1.0 MPa in increments of 0.1 MPa, for a total of 10 sets of experiments. The changes in the pipe's strain field and acoustic field were detected under different pressure conditions, from no leak to leak. Fiber Bragg gratings were selected as the sensing unit for the suspended strain field test, and unidirectional and tridirectional accelerometers were used as the sensing units for the suspended acoustic field test. Sensor types are as follows: Figure 5 As shown.

[0107] Regarding the characteristics of the suspended acoustic field, due to the large amount of data, only a leak diameter of 10mm and an internal pressure of 0.4MPa were selected for comparative analysis of the changes in the acoustic field before and after pipeline leakage. For example... Figure 2 It can be seen that the dynamic signals measured by the three unidirectional sensors and the two tridirectional sensors along the Z-axis are in the same direction, therefore they can be classified into one type of analysis, which uses sensors #1, #2, #3, and #4 respectively. z To the sensor and #5 z Mark the sensors; use #4 for the X-axis direction of the two triaxial sensors respectively. x To the sensor and #5 x Mark the sensor, Y-axis with #4y To the sensor and #5 y Label the sensors. Here, we'll label sensors #1, #2, #3, and #4. z To the sensor and #5 z The direction of the sensor test signal is defined as perpendicular to the pipe axis (Z-axis); #4 x To the sensor and #5 x The direction of the sensor test signal is defined as parallel to the pipe axis (X-axis); #4 y To the sensor and #5 y The direction of the sensor test signal is defined as parallel to the radial direction of the pipe (Y-axis).

[0108] like Figure 4 The frequency domain response characteristics of the acoustic field in each direction of the pipeline under an internal pressure of 0.4 MPa and without leakage. When the pipeline is leak-free, the... Figure 4 (a) Frequency domain signal characteristics of the vertical pipe along the axial direction (Z-axis). It can be seen that the natural frequencies of the vertical pipe along the axial direction are mainly distributed in four frequency bands: 12Hz, 24Hz, 48Hz, and 146Hz. Figure 4 (b) Frequency domain signal characteristics (X-axis) of parallel pipe axial direction. It can be seen that the natural frequencies of the parallel pipe axial direction are mainly distributed in four frequency bands: 24Hz, 48Hz, 97Hz, and 146Hz. Figure 4 (c) Radial frequency domain signal characteristics (Y-axis) of parallel pipes: It can be seen that the natural frequencies of the parallel pipes are mainly distributed in four frequency bands: 12Hz, 48Hz, 146Hz, and 256Hz. As can be seen from the time domain signal characteristics of the three figures, the signal is relatively stable when there is no leakage, and the external interference is small.

[0109] The attached figures below show the frequency domain signal response characteristics of the acoustic field in various directions during leakage under an internal pressure of 0.4 MPa. Figure 5 Frequency domain signal response characteristics of sensor #1 Figure 6 Frequency domain signal response characteristics of sensor #2 Figure 7 Frequency domain signal response characteristics of sensor #3 Figure 8 #4 z To the frequency domain signal response characteristics of the sensor, Figure 9 #5 z The frequency domain signal response characteristics of the sensors are all perpendicular to the pipe axis, i.e., the Z-axis. Sensors #1 and #3 are symmetrically located upstream and downstream of the leak, with a spacing of 4m. Sensor #4... z To the sensor and #5 z The sensors are also symmetrically positioned upstream and downstream of the leak, with a spacing of 0.6m. Sensor #2 is located at the leak outlet. Frequency domain signals show that sensors #2 and #4... z To the sensor, #5 zThe signal characteristics of the three sensors are basically the same, with four main frequency bands during leakage: 3.5 kHz, 4.7 kHz, 5.9 kHz, and 7.0 kHz. The signal characteristics of sensors #1 and #3 are also quite similar. Sensor #1 has four main frequencies: 2.0 kHz, 3.5 kHz, 4.7 kHz, and 5.9 kHz, while sensor #3 has three main frequencies: 3.5 kHz, 4.7 kHz, and 5.9 kHz. Figure 10 The frequency domain signal response characteristics of sensor #4x and Figure 11 #5 x The dominant frequencies of the frequency domain signal response characteristics of the sensors are relatively consistent. Sensor #4 has four dominant frequencies: 2.0 kHz, 3.5 kHz, 4.7 kHz, and 5.9 kHz. Sensor #5... x The sensor has five main frequencies: 2.0 kHz, 3.5 kHz, 4.7 kHz, 5.9 kHz, and 7.0 kHz; among them, Figure 12 #4 y To the frequency domain signal response characteristics of the sensor and Figure 13 #5 y The frequency domain signal response characteristics of the sensors are relatively consistent, #4 y The sensor has six main frequencies: 720 Hz, 2.0 kHz, 3.5 kHz, 4.7 kHz, 5.9 kHz, and 9.4 kHz. (5#) y The sensor has six main frequencies: 720 Hz, 2.0 kHz, 3.5 kHz, 4.7 kHz, 5.9 kHz, and 7.0 kHz. It is evident that during pipeline leakage, the frequency domain signal response in all directions exhibits the 3.5 kHz, 4.7 kHz, and 5.9 kHz frequency bands, which are its common main frequencies.

[0110] In summary, based on the differences in the vibration signals of suspended acoustic fields, the frequency domain signal distribution characteristics of suspended gas pipelines before and after leakage can be effectively captured. Before leakage, the pipeline's inherent frequencies are mainly low-frequency signals such as 12 Hz, 24 Hz, 48 Hz, 97 Hz, 146 Hz, and 256 Hz. During leakage, higher frequency signals are generated, mainly including 2.0 kHz, 3.5 kHz, 4.7 kHz, 5.9 kHz, 7.0 kHz, and 9.4 kHz, among which the 3.5 kHz, 4.7 kHz, and 5.9 kHz frequency bands are common dominant frequencies.

[0111] Regarding the strain field characteristics, circumferential fiber optic grating sensors are symmetrically arranged upstream and downstream of the leak, with a spacing of 4m. The two upstream sensors are defined as sensor #1 and sensor #2 grating points, and the two downstream sensors are defined as sensor #3 and sensor #4 grating points.

[0112] Furthermore, when the leak diameter is 3mm and 5mm, the instrument's accuracy is insufficient to capture the circumferential strain of the pipeline under small-diameter leaks due to the small leak diameter. Here, we only select a 10mm leak diameter and a 0.4MPa leak condition to study the circumferential strain variation of the pipeline. Figure 14 This is a dynamic change diagram of the fiber Bragg grating wavelength at the grating points of sensors #1, #2, #3, and #4 on the pipeline during a pipeline leak under a pressure of 0.4 MPa. Figure 14 (a) Wavelength variation diagram upstream of the leak outlet and Figure 14 (b) The circumferential wavelength variation diagram downstream of the leak shows that the wavelengths of all four grating points decrease at the instant the leak occurs. The fiber gratings located upstream and downstream of the leak both decrease to 0.001 nm, corresponding to a decrease in tube strain of -0.845 με at the time of the leak, indicating that both are under pressure.

[0113] Furthermore, by monitoring the circumferential strain of a suspended pipeline before and after a leak, it can be seen that when the pressure inside the pipe changes, the circumferential strain of the outer wall of the pipe also changes accordingly, and the two are directly proportional. When a pipeline leaks, the fluid at the leak point rapidly flows out, the pressure drops, and the gas on both sides of the leak point replenishes the leak point due to the pressure difference. This process is transmitted upstream and downstream sequentially, equivalent to the generation of a negative pressure wave propagating at a certain speed at the leak point. As the negative pressure wave propagates along the pipeline, it will cause a momentary decrease in pipeline pressure. Pipeline leakage is a short-term event, and the pipe wall thickness can be considered constant at the moment of leakage. The pressure change inside the pipeline will cause a change in the circumferential strain of the outer wall of the pipe. Therefore, the presence of a pipeline leak can be detected by monitoring the change in the circumferential strain of the pipeline.

[0114] For the acoustic wave field source tracing and location method, the suspended acoustic wave field location relies on the frequency domain characteristics difference of the vibration signals before and after the pipeline leak and the signal response law of the spatial distribution of the sensor. The leak point is located through three steps: "feature recognition - location determination - accuracy optimization".

[0115] ① Preliminary Leakage Characteristic Assessment: Leakage Identification Based on Dominant Frequency Distribution A leakage state identification model is constructed by utilizing the differences in the frequency domain characteristics of the acoustic field observed in the experiment: Leakage-free determination: When the main frequency of the vibration signal collected by the sensors in all directions is concentrated in the low frequency range such as 12 Hz, 24 Hz, 48 Hz, 97 Hz, 146 Hz, and 256 Hz, the pipeline is determined to be in a leak-free state. Leakage detection: When high-frequency bands such as 2.0K Hz, 3.5K Hz, 4.7K Hz, and 5.9K Hz appear in the signal, and 3.5K Hz, 4.7K Hz, and 5.9K Hz are common main frequencies, it is determined that the pipeline has leaked. This step can be automated by setting a frequency threshold algorithm to identify and exclude invalid location calculations in the absence of leakage. ② Coarse Leakage Location: Based on the difference in signal response from the spatial distribution of sensors Based on the sensor placement and signal characteristics observed in the experiment, sensors were symmetrically deployed at the leak point and upstream and downstream, with a spacing of 4m / 0.6m. A correlation was established between "sensor group signal matching degree - distance to leak point": Within 0.6m of the leak point: When #4 z To the sensor, #5 z The sensors were symmetrically arranged 0.6m upstream and downstream of the leak. When the signal characteristics of the sensors were highly consistent with those of the No. 2 sensor at the leak, i.e., when the main frequencies of 3.5K Hz, 4.7K Hz, 5.9K Hz and 7.0K Hz appeared, it was determined that the leak point was located within the coverage area of ​​the sensor group within 0.6m. Locating the leak point within 4m of the far zone: When sensors #1 and #3 are symmetrically deployed 4m upstream and downstream of the leak point and only 3.5KHz, 4.7KHz, and 5.9KHz are observed, with a 7.0KHz main frequency missing, the leak point is determined to be located within the 4m coverage area of ​​that set of sensors. Directional dimension-assisted positioning: parallel to the pipe radial (Y-axis, 4#) y To the sensor, #5 y A unique 720 Hz main frequency appeared in the sensor, parallel to the pipe axis (X-axis, sensor #4, sensor #5). x The sensor exhibits a fundamental frequency of 2.0 kHz, which, combined with directional characteristics, can further narrow the radial / axial range of the leak point. ③ Positioning accuracy optimization: Precise calculation based on vibration wave propagation time difference Utilizing the propagation speed of vibration signals in pipelines (the propagation speed of elastic waves in gas pipelines is approximately...) v =5000 (6000m / s), combined with the time difference Δ between the leakage characteristic signals collected by upstream and downstream sensors. t The distance between the leak point and the sensor is calculated using a formula:

[0116] in, LThis represents the distance from the leak point to the midpoint between the upstream and downstream sensors. If the sensors are asymmetrically arranged, a sensor spacing correction formula needs to be used. In the experiment, the distance between sensors #1 and #3 was 4m. This method can improve the positioning accuracy from "interval level" to "meter level".

[0117] Regarding the strain field source tracing and location method, strain field location is based on the circumferential strain change of the pipeline caused by the propagation of negative pressure waves. Combined with the strain monitoring data of fiber optic gratings, the source tracing is achieved through "strain mutation identification - negative pressure wave propagation time difference calculation - leak point location". At the same time, improvement strategies are proposed to address the monitoring shortcomings of small-diameter leaks.

[0118] ① Leakage strain characteristic identification: Abrupt detection based on fiber optic grating wavelength variation In the experiment, under a 10mm leak diameter and 0.4MPa pressure, the wavelength of each fiber optic grating point (sensor #1-sensor #4) decreased by 0.001nm at the instant of leakage, corresponding to a decrease in circumferential strain. 0.845 με (under pressure). Based on this, a strain abrupt change judgment rule is constructed: Baseline establishment: Collect fiber optic grating wavelength data during stable pipeline operation to serve as the strain baseline under leak-free conditions. Mutation identification: When a sudden decrease in wavelength is detected and the change reaches 0.001 nm, the corresponding strain... At 0.845 με, the strain mutation was determined to be caused by leakage. Supplement for small-diameter leaks: To address the difficulty in detecting leaks in 3mm and 5mm diameters, replace with a high-precision fiber optic grating sensor (accuracy ≤0.0001nm) or use differential grating technology to amplify minute strain signals and achieve strain monitoring of small-diameter leaks. ② Leakage point location: Based on the time difference algorithm of negative pressure wave propagation The negative pressure wave generated when a pipeline leaks travels at a constant speed. (The propagation speed of negative pressure waves in gas pipelines is approximately 300 km / h) The strain propagation speed is 400 m / s along the axial direction of the pipeline, combined with the time difference of strain change at the upstream and downstream fiber optic grating points. Calculate the location of the leak:

[0119] in, The spacing between the upstream and downstream gate points is 4m in the experiment. This represents the distance from the leak point to the upstream gate point.

[0120] In the experiment, the upstream sensor #1 and sensor #2 grid points and the downstream sensor #3 and sensor #4 grid points were symmetrically arranged (4m apart). If the upstream grid point detected a sudden change in strain first, it indicates that the leak point is close to the upstream; if the downstream grid point detected it first, it is close to the downstream; if they were detected simultaneously, it indicates that the leak point is located at the midpoint of the grid points (i.e., the leak outlet in the experiment).

[0121] ③ Error correction for strain field positioning Changes in pipeline pressure result in a direct proportional relationship between circumferential strain and pressure, necessitating the inclusion of a pressure compensation coefficient in the positioning calculations. The baseline values ​​of the circumferential strain of the pipeline under different internal pressures (0.1MPa~1.0MPa) were pre-calibrated experimentally, and a pressure-strain calibration curve was established. During location, the threshold for strain mutation is corrected based on real-time internal pressure data to eliminate the interference of pressure fluctuations on leak detection.

[0122] 5) Optimization of source tracing and localization through multi-field fusion of strain field and acoustic field Single-field acoustic or strain field localization has limitations: acoustic fields are easily affected by environmental vibrations, and strain fields have very low sensitivity to small-diameter leaks. Multi-field fusion can achieve complementary advantages, improving both localization accuracy and reliability. ① Integrated positioning logic State coordination determination: When the acoustic field detects high-frequency dominant frequency characteristics and the strain field detects strain abrupt change, the leak location process is triggered together to eliminate false alarms from a single sensor (such as abnormal acoustic signals caused by environmental vibration or strain changes caused by pressure fluctuations). Location cross-verification: The distance results from the acoustic field positioning are cross-compared with the distance results from the strain field positioning, and the intersection of the two is taken as the final leakage point range; if the result deviation exceeds the threshold (e.g., 0.5m), a second monitoring verification is initiated. ② Implementation of Fusion Positioning Algorithm A weighted fusion algorithm is used to assign weights based on the sensor accuracy in different scenarios: For large-diameter leaks (≥10mm), the strain field signal is clear, giving weight to the strain field localization results. =0.6, sound wave field weight =0.4; When the leakage is small (<10mm), the characteristics of the sound wave field are more obvious, giving the sound wave field a weight. =0.7, strain field weight =0.3; Final positioning result, ,in To determine the distance for the strain field, To determine the distance of the sound wave field.

[0123] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0124] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A gas pipeline leakage simulation platform, characterized in that, It includes a gas source generation and collection module and a gas source delivery module, as well as a near-end manhole and a far-end manhole for simulating gas pipeline leakage experiments under different burial depth conditions; The gas source generation and gas collection module includes an air compressor (1), a gas storage tank (2), a refrigerated dryer (6), and a filter (3), which are connected in sequence through pipeline connecting hoses (4); The gas source delivery module includes a pressure reducing valve (5), an inlet pressure sensor (7), an inlet flow sensor (8), a manhole vertical diversion steel pipe (10), a manhole connecting steel pipe (11), a leak point test steel pipe (13), an outlet flow sensor (14), an outlet pressure sensor (15), and a venting valve (16); a leak point test steel pipe (13) is set between the two manhole connecting steel pipes (11), and a leak point electromagnetic ball valve assembly (12) is installed on the leak point test steel pipe (13); the gas source delivery module is connected to the filter (3) of the gas source generation and gas collection module through the pressure reducing valve (5); The pressure reducing valve (5), the air inlet pressure sensor (7) and the air inlet flow sensor (8) are connected in sequence and then connected to the manhole vertical diversion steel pipe (10) in the near end manhole through the manhole quick-connect hose (9). The outlet flow sensor (14), outlet pressure sensor (15), and vent valve (16) are connected in sequence and then connected to the manhole vertical diversion steel pipe (10) in the far end manhole through the manhole quick-connect hose (9).

2. The gas pipeline leakage simulation platform according to claim 1, characterized in that, The manhole vertical diversion steel pipe (10) in the near end manhole or the far end manhole is provided with branch holes at intervals along the axial direction, and each branch hole is connected by a manhole connecting steel pipe (11).

3. A multi-site source tracing and location system for gas pipeline leaks, characterized in that, The gas pipeline leakage simulation platform according to any one of claims 1-2, wherein the source tracing and positioning system includes a suspended gas pipeline area module and a buried gas pipeline area module, and the suspended gas pipeline area module and the buried gas pipeline area module are deployed on the gas pipeline leakage simulation platform. The suspended gas pipeline area module involves a suspended strain field and a suspended sound wave field, while the buried gas pipeline area module involves a buried sound wave field, a buried geoelectric field, and a buried strain-temperature field. The suspended gas pipeline area module includes a suspended strain field monitoring unit, a suspended acoustic wave field monitoring unit, a suspended data processing unit, and a suspended space positioning unit. The buried gas pipeline area module includes a buried acoustic field testing unit, a buried geoelectric field testing unit, a buried strain-temperature field testing unit, and a buried data collaborative processing unit.

4. A multi-site source tracing and location system for gas pipeline leaks according to claim 3, characterized in that, The specific contents of the suspended gas pipeline area module are as follows: The suspended strain field monitoring unit uses fiber optic grating sensors, which are deployed on the test steel pipe (13) at the leakage point using a uniform or dense arrangement method to collect suspended strain field monitoring data. The suspended acoustic wave field monitoring unit uses a unidirectional or tridirectional accelerometer sensor to collect suspended acoustic wave field monitoring data. The suspended acoustic wave field is deployed at the same point as the fiber optic grating sensor of the suspended strain field. The suspended data processing unit performs preprocessing, feature extraction, and feature fusion on the suspended strain field monitoring data and the suspended acoustic wave field monitoring data, and outputs the identification result of the suspended gas pipeline leak point. The suspended space positioning unit, based on the identification results of the suspended gas pipeline leak point output by the suspended data processing unit, performs accurate positioning through a time difference positioning algorithm and outputs the distance between the leak point location and the sensor location.

5. A multi-site source tracing and location system for gas pipeline leaks according to claim 3, characterized in that, The specific contents of the buried gas pipeline area module are as follows: The buried acoustic field test unit uses a low-frequency seismic wave detector arranged in a cross-shaped array structure to collect buried acoustic field test data. The buried electric field testing unit uses non-polarized electrodes arranged in a high-density grid structure to collect buried electric field test data. The buried strain-temperature field testing unit uses tight-buffered and loose-buffered optical cables arranged in a three-dimensional sensor network structure to collect buried strain-temperature field test data within the monitoring range of buried acoustic wave field and buried geoelectric field. The buried data collaborative processing unit performs preprocessing, feature extraction, fusion analysis, and three-dimensional source tracing and positioning operations on the buried acoustic field test data, the buried geoelectric field test data, and the buried strain-temperature field test data, and outputs the three-dimensional coordinates of the leak point.

6. A multi-site source tracing and location system for gas pipeline leaks according to claim 4, characterized in that, The sensitive axis of the unidirectional acceleration sensor in the suspended acoustic field monitoring unit is aligned with the axial direction of the leak point test steel pipe (13), and the sensitive axis of the tridirectional acceleration sensor covers the axial, radial horizontal and radial vertical directions of the leak point test steel pipe (13).

7. A multi-site source tracing and location system for gas pipeline leaks according to claim 4, characterized in that, The suspended data processing unit includes a suspended strain data preprocessing module, a suspended acoustic wave data preprocessing module, a suspended feature extraction module, and a suspended feature fusion module. The suspended strain data preprocessing module performs temperature compensation and baseline correction on the suspended strain field monitoring data. The suspended acoustic wave data preprocessing module performs frequency band filtering, adaptive noise reduction, and signal normalization on the suspended acoustic wave field monitoring data. The suspended feature extraction module is used to extract the dynamic and spatial features of the preprocessed suspended strain field monitoring data, and to extract the time domain features, frequency domain features, and spatial propagation features of the preprocessed suspended acoustic wave field data. The suspended feature fusion module is used for spatiotemporal matching, weight assignment, and spatial fusion positioning of the suspended strain field and the suspended acoustic wave field to generate the identification result of the leak point of the suspended gas pipeline.

8. A multi-site source tracing and location system for gas pipeline leaks according to claim 5, characterized in that, The buried data collaborative processing unit includes a buried multi-field data preprocessing module, a buried feature extraction module, a buried fusion analysis module, and a buried three-dimensional tracing and positioning module; The buried multi-field data preprocessing module performs preprocessing operations such as synchronous correction, filtering and noise reduction, and signal normalization on the buried acoustic field test data; performs preprocessing operations such as polarization drift compensation, grounding resistance correction, background field subtraction, and resistivity conversion on the buried geoelectric field test data; and performs preprocessing operations such as coupling signal separation, spatial interpolation completion, and baseline update on the buried strain-temperature field test data. The buried feature extraction module is used to extract the time-domain, frequency-domain, and spatial features of the buried acoustic field, the buried geoelectric field, and the buried strain-temperature field. The buried fusion analysis module, based on the fusion logic of spatiotemporal matching-weight adaptation-conflict adjudication, calculates the fusion confidence of the features output by the buried feature extraction module; Based on the fusion confidence level and the preset leak detection strategy, a leak detection result is generated for gas leak detection. The buried three-dimensional tracing and positioning module, based on the gas leak judgment result and the buried acoustic field test data, buried geoelectric field test data, and buried strain-temperature field test data, outputs the three-dimensional positioning coordinates of the buried gas pipeline leak point.

9. A multi-site source tracing and location system for gas pipeline leaks according to claim 8, characterized in that, The method for calculating the fusion confidence level is as follows: Fusion confidence = Σ (single-source anomaly probability × corresponding weight); Among them, the single-source anomaly probability is the anomaly probability of any one of the physical fields, namely the buried acoustic wave field, the buried geoelectric field, and the strain-temperature field.

10. A multi-site source tracing and location system for gas pipeline leaks according to claim 4, characterized in that, The time difference positioning algorithm formula used in the suspended space positioning unit is: ； In the formula, and For different receiving times, and These are the coordinates of the point. For the speed of sound wave propagation, This refers to the distance between the output leak point location and the sensor location.

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