Distributed optical fiber leakage detection method, device and system

Abstract

The invention relates to the technical field of pipeline monitoring, in particular to a distributed optical fiber leakage detection method, device and system, and the method comprises the steps: S1, building a space gridding sensing scheme according to the parameters of the length and diameter of a pipeline, laying sensing optical fibers into a grid shape according to a transverse plane and a longitudinal plane in sequence, and then covering the surface of the pipeline with the sensing optical fibers; s2, building an underground pipe network temperature and vibration distributed optical fiber detection system for collecting environment signals; s3, environment signal data are collected and analyzed, and an environment signal rule analysis model under the normal working condition is established; s4, optical fiber signal abnormal points are obtained in real time through a distributed optical fiber detection system, and the possible leakage position of the pipeline is calculated; and S5, analyzing the temperature and vibration indexes of the pipeline at the position where leakage possibly occurs, and judging whether leakage occurs or not. The problem that a sensor is difficult to detect a long-distance pipeline is solved, abnormal values are compared with normal values, sudden change points of temperature and vibration are determined, and therefore the leakage point of the pipe network is accurately positioned.

Description

Technical Field

[0001] The present invention relates to the technical field of pipeline monitoring, and in particular to a distributed optical fiber leakage detection method, device and system. Background Art

[0002] The underground pipe network is an important part of urban infrastructure. It undertakes the transportation functions of urban water supply, gas and electricity, and plays an important role in urban economic development. With the increase in the service life of underground pipe networks and the aging of their own materials, the leakage problem of pipe networks has become increasingly prominent, bringing huge challenges to related enterprises and society; the problem of pipeline leakage will not only cause huge economic losses to the pipe network management companies, but also waste a lot of valuable resources, and there are uncontrollable safety risks, such as causing road cavities, ground subsidence, gas explosions and other problems, which pose a serious threat to the safety of towns, the normal life of residents and traffic safety. Therefore, underground pipe network leakage detection is particularly important.

[0003] At present, there are two main conventional pipeline monitoring and protection methods: one is external monitoring and protection, such as pipeline inspection, early warning instrument detection monitoring, and pipeline corridor online monitoring system, and the other is a built-in safety protection system, such as pipeline flow and pressure monitoring. For example, the publication number CN112629701A provides a pipeline leakage monitoring system and leakage point positioning method based on distributed optical fiber temperature measurement technology. The optical fiber is wound on the surface of the pipeline to be tested in the form of a two-dimensional grid and connected to the temperature measurement host. The temperature change of the pipeline surface is monitored by the optical fiber in the form of a two-dimensional grid, and the leakage point range is determined by the area composed of the grid edges with abnormal temperature field. It is impossible to accurately determine the leakage point by only setting a two-dimensional grid temperature measurement scheme on the pipeline, and this method adopts a back-and-forth arrangement method in different regions, which improves the signal strength, but ignores the measurement uncertainty caused by the large number of arrangement points, resulting in errors in the results. Therefore, how to realize the health detection of urban underground pipelines, timely detect abnormalities, accurately locate, and accurately alarm is a problem that technicians in this field need to solve urgently. Summary of the invention

[0004] In order to solve the problems in the above-mentioned background technology, the present invention provides a distributed optical fiber leakage detection method, device and system, which can solve the problems of underground pipeline leakage detection and application limitations caused by inaccurate single detection data.

[0005] To achieve the above purpose, the technical solution provided by the present invention is as follows:

[0006] A distributed optical fiber leakage detection method comprises the following steps:

[0007] S1: Based on the parameters of pipeline length and diameter, a spatial grid-based sensing scheme is established. The sensing optical fiber is laid out in a grid shape along the horizontal and vertical planes, and then covered on the pipeline surface.

[0008] S2: According to the grid layout of optical fibers, a distributed optical fiber detection system for underground pipe network temperature and vibration is built to collect environmental signal data;

[0009] S3: Establishing an environmental signal law analysis model under normal working conditions;

[0010] S4: Real-time acquisition of environmental signal data through the distributed optical fiber leakage detection system, and calculation of possible pipeline leakage locations based on signal anomalies;

[0011] S5: Analyze the pipeline temperature and vibration signal data at the location where leakage may occur, compare the data of the abnormal signal point, and determine whether leakage occurs.

[0012] Preferably, the specific process of establishing the environmental signal law analysis model under normal working conditions in step S3 includes:

[0013] S31: Grid-shaped sensing optical fiber coverage on the detection pipeline;

[0014] S32: According to actual engineering cases, characteristic values ​​of temperature and vibration data of the pipeline under historical leakage conditions and characteristic values ​​of temperature and vibration data under normal conditions are obtained;

[0015] S33: The characteristic values ​​of the data under normal working conditions are compared with the characteristic values ​​of the comparative data under leakage working conditions, the data noise is eliminated, and an environmental signal law analysis model is established.

[0016] Specifically, the specific steps of calculating the possible leakage position of the pipeline in step S4 include:

[0017] S41: according to the temperature and vibration signal data under normal working conditions, the difference of the data characteristic values ​​under normal working conditions is calculated and stored in the historical working condition database;

[0018] S42: Obtaining the optical fiber detection signal in real time, comparing the data difference of the optical fiber detection point with the difference in the historical working condition database, if the comparison meets the standard of normal working condition, the sensor output result is normal, if the comparison does not meet the standard of normal working condition, calculating the abnormal value of the output signal, and determining the optical fiber detection signal corresponding to the abnormal value;

[0019] S43: According to the abnormal optical fiber detection signal, the mutation point of the temperature and vibration signal is determined, and then the actual position of the underground pipeline in the corresponding grid area is calculated through the grid points.

[0020] Furthermore, the specific process of step S5 includes:

[0021] S51: collecting abnormal optical fiber detection signal data of temperature and vibration of the pipeline that may leak and eliminating data noise;

[0022] S52: According to the database of historical working conditions, determine the leakage medium and accident model in the pipeline, model and simulate the pipeline leakage accident, and establish a leakage accident model data set;

[0023] S53: collecting and processing a pipeline leakage accident model data set, calculating the temperature-time and vibration frequency-time data of the pipeline and the surrounding space after the pipeline leakage accident occurs through finite element simulation, and determining the maximum value of the temperature and vibration changes around the pipeline;

[0024] S54: Analyze the environmental signal using the principal component analysis method to remove the environmental noise data in the maximum value;

[0025] S55: Compare the environmental characteristic information with the environmental signal law analysis model under normal working conditions to determine whether leakage occurs.

[0026] The hardware part of the distributed optical fiber leakage detection system includes a distributed optical fiber leakage detection device, that is, a distributed optical fiber temperature measurement host, a computer, a plurality of data amplifiers, a data analysis device, and a dynamic test device; the distributed optical fiber temperature measurement host is connected to the dynamic test device; the dynamic test device is connected to the data amplifier; the distributed optical fiber temperature and vibration detection device is used to collect temperature and vibration data on the optical fiber in the distributed optical fiber temperature measurement host.

[0027] Furthermore, the distributed optical fiber temperature measurement host is connected to a dynamic test device, which includes a test bracket and a test wiring; the test bracket is fixedly mounted on the outer wall of the pipeline to be tested, and the test wiring is mounted on the test bracket, and a plurality of S-shaped sleeves are wrapped around the distributed optical fiber temperature and vibration monitoring device; two adjacent S-shaped sleeves are connected by a fixing device; the sensing optical fiber in the distributed optical fiber leakage detection device is wired along the entire length of the pipeline, and the wiring form of the sensing optical fiber is as follows: the length and diameter parameters of the pipeline are obtained, and the sensing optical fiber is laid on the outermost layer of the pipeline according to the grid plane, covering the entire pipe wall surface, and the grid is laid at intervals of 0.2m*0.2m to set a square grid.

[0028] A distributed optical fiber leakage detection system comprises a historical operating condition database, a sensing optical fiber, a signal preprocessor, a sensing signal database, and a solution module; the signal preprocessor is used to preprocess the collected environmental signals, temperature and vibration signals; the solution module is used to solve and analyze the preprocessed signals with the accident data in the historical operating condition database to obtain the accident result; the working process of the system is as follows: the environmental signals, temperature and vibration signals collected by the distributed optical fiber detection system are preprocessed by the signal preprocessor, and then compared with the signals in the sensing signal database in the solution module to determine the accident characteristics and output the results; the working process of the system is as follows:

[0029] S101: collecting optical fiber temperature and vibration data through a distributed optical fiber leakage detection system and preprocessing the data;

[0030] S102: Identify the pipeline environment signal status, if abnormal, then go to S103; if normal, then return to S101 to continue running the system;

[0031] S103: Determine the spatial scope and location of the accident impact by comparing the data in the historical operating condition database with the data in the sensor signal database;

[0032] S104: Based on the result of S103, identify the pipeline in the abnormal area and determine whether leakage occurs.

[0033] Furthermore, the specific process of identifying the pipeline environment status in step S102 includes:

[0034] S1021: Calculate the temperature change value at each position of the optical fiber, process signal characteristics, analyze the vibration spectrum, and analyze the environmental signal at the same time, so as to obtain a feature vector data set of the optical fiber temperature and vibration signal in the area, and calculate it;

[0035] S1022: Obtain the ambient temperature T' and vibration frequency V' in the pipeline environmental state; obtain the real temperature T and vibration frequency V data of the accident data; calculate the difference under the environment, compare it with the temperature and vibration difference under historical working conditions, and determine the abnormal signal A = (A1, A2, ..., An).

[0036] Furthermore, the process of obtaining the feature vector data set in S1021 includes establishing a multidimensional feature vector set: storing the data set obtained during the optical fiber temperature measurement and detection process in a sensor signal database, processing it in combination with the system data obtained by the optical fiber leakage detection system, and performing matrix representation to obtain a multidimensional feature vector set.

[0037] Furthermore, the position of the abnormal signal A is determined in S1022; the area (A1, A2, ..., Am) where the abnormal signal A is located in the multidimensional feature vector set is determined, by calculating the abnormal point Amin'=minA', where A' represents the multidimensional feature vector set, Amin' is the smallest signal feature vector of the abnormal area A, and the signal feature vector minA' is the location of the leakage point.

[0038] The present invention has the following beneficial effects:

[0039] 1. In the leakage detection and positioning of underground pipe networks, the operating temperature and vibration frequency index changes of the pipe network are monitored to solve the problem that sensors are difficult to detect long-distance pipes. By using dynamic testing equipment, the temperature and vibration signal strength problems are solved, and the detection accuracy and safety are improved;

[0040] 2. By collecting the temperature signal and vibration frequency signal when there is no leakage on the pipeline surface, the signal when there is no leakage is determined as the normal value signal; the temperature and vibration frequency signals when there is leakage are changed into abnormal signal values; the abnormal values ​​are compared with the normal values ​​to determine the mutation points of temperature and vibration, so as to accurately locate the leakage points of the pipeline network;

[0041] 3. Use a distributed fiber optic detection system for real-time monitoring, and combine fiber optic equipment and dynamic testing equipment to identify hazardous sources and realize real-time early warning of temperature and vibration data in the pipeline; and use dynamic testing equipment to analyze and warn of the location, hazard level, historical data, etc. of hazardous sources along the pipeline network, thereby realizing dynamic testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a one-dimensional plane development diagram of the grid-like laying of sensing optical fibers in an embodiment of the present invention;

[0043] Figure 2 is a primary template diagram of a detection signal in an embodiment of the present invention;

[0044] Figure 3 is a final template diagram of the detection signal in an embodiment of the present invention;

[0045] Figure 4 is a signal diagram of a straight-line laying detection of optical fiber in an embodiment of the present invention;

[0046] Figure 5 is a signal diagram of optical fiber U-shaped laying detection in an embodiment of the present invention;

[0047] Figure 6 It is a diagram of the optical fiber grid-shaped laying detection signal in an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The technical solutions in the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. The components of the present invention generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0049] It needs to be explained that the environmental signals in this patent include those collected by other sensors or monitoring equipment through manual inspection or automatic detection, and the environmental information around the pipeline includes physical parameter data information such as pressure, humidity, concentration of harmful gases, light intensity, etc., which are used as the different environments of different sections of the pipeline.

[0050] In order to solve the problems of underground pipeline leakage detection and application limitations caused by inaccurate single detection data, the present invention provides a distributed optical fiber leakage detection method, device, and system, wherein the device includes a distributed optical fiber temperature measurement host, a computer, a plurality of data amplifiers, a data analysis device, and a dynamic testing device; the distributed optical fiber temperature measurement host is connected to the dynamic testing device; the dynamic testing device is connected to the data amplifier; and the distributed optical fiber temperature and vibration detection device is used to collect temperature and vibration data on the optical fiber in the distributed optical fiber temperature measurement host.

[0051] The distributed optical fiber temperature measurement host is connected to the dynamic test equipment, which includes a test bracket and a test wiring. The test bracket is fixedly installed on the outer wall of the pipeline to be tested, and the test wiring is installed on the test bracket and is surrounded by a plurality of S-shaped sleeves on the distributed optical fiber temperature and vibration monitoring device. Two adjacent S-shaped sleeves buried underground are connected by a fixing device. The distributed optical fiber temperature and vibration detection device is wired along the entire length of the pipeline through the sensing optical fiber. Please refer to Figure 1 The one-dimensional plane expansion diagram of the sensor optical fiber network format is shown in Figure 1. i is the horizontal coordinate of the sensing optical fiber after it is flattened into one dimension in a grid shape, Y i is the longitudinal coordinate of the sensing fiber grid after it is flattened into one dimension, L i is the equally spaced interval of the square grid, Figure 1 L 2 ~L 7 It is used to indicate the arrangement sequence of the sensing optical fiber, that is, the sensing optical fiber is arranged along L 2至 L 7The wiring of the sensing optical fiber is carried out according to the trend. The wiring form of the sensing optical fiber is as follows: the length and diameter parameters of the pipeline are obtained, and the sensing optical fiber is laid on the outermost layer of the pipeline according to the grid plane, covering the entire surface of the pipe wall. The grid is laid at intervals of 0.2m*0.2m to set a square grid, so that the coordinate position of each optical fiber detection point on the pipeline can be determined to determine the leakage detection point.

[0052] See also Figure 2 The primary template diagram of the detection signal and Figure 3 The ultimate template diagram of the detection signal, in this embodiment, a distributed optical fiber sensing system is used to simulate a small-scale optical fiber grid measurement of a water pipe leakage monitoring experiment. In the small-scale pipeline leakage simulation experiment, the selected optical fiber length is 180m; the tap water pipe adopts a DN300 steel pipe, the water temperature in the pipe is controlled at 18°C, and the external environment temperature is controlled at 23C; the leakage of the pipe is artificially controlled by a valve, which is set 3.2 meters above the test pipe.

[0053] Before the pipeline leakage detection experiment begins, take 50 groups of non-leaking signals and divide them into early signals (10 groups), mid-term signals (10 groups) and late signals (30 groups). Please refer to Figure 2 First, the initial signal is preprocessed, and then the primary template is determined by comparing the correlation coefficient with the mid-term signal; please refer to Figure 3 , and then calculate the difference coefficients between the 30 groups of late signals and the primary template signals respectively. After eliminating the large difference values, the remaining signals are accumulated and averaged and normalized to determine the final template signal.

[0054] It includes a historical operating condition database, a sensing optical fiber, a signal preprocessor, a sensing signal database, and a solution module; the signal preprocessor is used to preprocess the collected environmental signals, temperature and vibration signals; the solution module is used to solve and analyze the preprocessed signals with the accident data in the historical operating condition database to obtain the accident results; the working process of the system is as follows: the environmental signals, temperature and vibration signals collected by the distributed optical fiber detection system are preprocessed by the signal preprocessor, and then compared with the signals in the sensing signal database in the solution module to determine the accident characteristics and output the results.

[0055] The above-mentioned distributed optical fiber sensing system can monitor the changes in the operating temperature and vibration frequency indicators of the underground pipeline network during the leakage detection and positioning of the underground pipeline network, thereby solving the problem that the sensor is difficult to detect long-distance pipelines. By using dynamic testing equipment, the problem of temperature and vibration signal strength is solved, and by using monitoring devices for protection, the detection accuracy and safety are improved.

[0056] By collecting temperature signals and vibration frequency signals when there is no leakage on the pipeline surface, the signals when there is no leakage are determined as normal value signals; the temperature and vibration frequency signals when there is leakage are changed into abnormal signal values; the abnormal values ​​are compared with the normal values ​​to determine the mutation points of temperature and vibration, so as to accurately locate the leakage points of the pipeline network;

[0057] The method for optical fiber leakage detection using the above device and system comprises the following steps:

[0058] S1: Based on the parameters of pipeline length and diameter, a spatial grid-based sensing scheme is established. The sensing optical fiber is laid out in a grid shape along the horizontal and vertical planes, and then covered on the pipeline surface.

[0059] S2: According to the grid layout of optical fibers, a distributed optical fiber detection system for underground pipe network temperature and vibration is built to collect environmental signal data;

[0060] S3: Establishing an environmental signal law analysis model under normal working conditions;

[0061] S31: Grid-shaped sensing optical fiber coverage on the detection pipeline;

[0062] S32: According to actual engineering cases, characteristic values ​​of temperature and vibration data of the pipeline under historical leakage conditions and characteristic values ​​of temperature and vibration data under normal conditions are obtained;

[0063] S33: The characteristic values ​​of the data under normal working conditions are compared with the characteristic values ​​of the comparative data under leakage working conditions, the data noise is eliminated, and an environmental signal law analysis model is established.

[0064] S4: Real-time acquisition of environmental signal data through a distributed optical fiber leakage detection system, and calculation of possible pipeline leakage locations based on signal anomalies; the specific steps of calculating possible pipeline leakage locations in step S4 include:

[0065] S41: according to the temperature and vibration signal data under normal working conditions, the difference of the data characteristic values ​​under normal working conditions is calculated and stored in the historical working condition database;

[0066] S42: Obtaining the optical fiber detection signal in real time, comparing the data difference of the optical fiber detection point with the difference in the historical working condition database, if the comparison meets the standard of normal working condition, the sensor output result is normal, if the comparison does not meet the standard of normal working condition, calculating the abnormal value of the output signal, and determining the optical fiber detection signal corresponding to the abnormal value;

[0067] S43: According to the abnormal optical fiber detection signal, the mutation point of the temperature and vibration signal is determined, and then the actual position of the underground pipeline in the corresponding grid area is calculated through the grid points.

[0068] S5: Analyze the pipeline temperature and vibration signal data at the location where leakage may occur, compare the data of the abnormal signal point, and determine whether leakage occurs.

[0069] The specific process is:

[0070] S51: collecting abnormal optical fiber detection signal data of temperature and vibration of the pipeline that may leak and eliminating data noise;

[0071] S52: According to the database of historical working conditions, determine the leakage medium and accident model in the pipeline, model and simulate the pipeline leakage accident, and establish a leakage accident model data set;

[0072] S53: collecting and processing a pipeline leakage accident model data set, calculating the temperature-time and vibration frequency-time data of the pipeline and the surrounding space after the pipeline leakage accident occurs through finite element simulation, and determining the maximum value of the temperature and vibration changes around the pipeline;

[0073] S54: Analyze the environmental signal using the principal component analysis method to remove the environmental noise data in the maximum value;

[0074] S55: Compare the environmental characteristic information with the environmental signal law analysis model under normal working conditions to determine whether leakage occurs.

[0075] The working process of the distributed optical fiber leakage detection system is as follows:

[0076] S101: collecting optical fiber temperature and vibration data through a distributed optical fiber leakage detection system and preprocessing the data;

[0077] S102: Identify the pipeline environment signal status, if abnormal, then go to S103; if normal, then return to S101 to continue running the system;

[0078] The specific process of identifying the pipeline environment status in step S102 includes:

[0079] S1021: Calculate the temperature change value at each position of the optical fiber, process signal characteristics, analyze the vibration spectrum, and analyze the environmental signal at the same time, so as to obtain a feature vector data set of the optical fiber temperature and vibration signal in the area, and calculate it;

[0080] S1022: Obtain the ambient temperature T' and vibration frequency V' in the pipeline environmental state; obtain the real temperature T and vibration frequency V data of the accident data; calculate the difference under the environment, compare it with the temperature and vibration difference under historical working conditions, and determine the abnormal signal A = (A1, A2, ..., An).

[0081] In the S1022, the position of the abnormal signal A is determined; the area (A1, A2, ..., Am) where the abnormal signal A is located in the multidimensional feature vector set is determined, by calculating the abnormal point Amin'=minA', where A' represents the multidimensional feature vector set, Amin' is the minimum signal feature vector of the abnormal area A, and the signal feature vector minA' is the location of the leakage point.

[0082] S103: Determine the spatial scope and location of the accident impact by comparing the database with the real-time processing data;

[0083] S104: Based on the result of S103, identify the pipeline in the abnormal area and determine whether leakage occurs.

[0084] See also Figure 4 The optical fiber linear laying detection signal diagram is shown in Figure 1. During the experiment, the temperature signal of the pipeline when there is no leakage is obtained through the distributed optical fiber. 50 groups of pipeline no leakage detection signals are collected every minute. 30 groups of leakage detection signals of each laying method are compared with the final threshold template, and the leakage positioning effect of the pipeline under the three sensing optical fiber laying methods is obtained:

[0085] The sensing optical fiber is laid on the wall of the tap water pipe in a straight line, U-shaped and grid manner respectively. The distributed optical fiber sensing system collects the signal when there is no leakage on the pipeline surface. The reference threshold signal is determined according to the no-leakage signal. The threshold signal and the leakage signal are compared to determine the temperature and vibration mutation points.

[0086] Please refer to Figure 4 ,When the sensing optical fiber is laid in a straight line, the distributed optical fiber sensing signal changes significantly at 14.4m, and the temperature drops from 22 degrees to 20 degrees, indicating that the leakage point is at 4.4m of the pipeline. The actual leakage point is at 3.2m, and the positioning error is 1.2m;

[0087] See also Figure 5 The optical fiber U-shaped laying detection signal diagram shows that when the sensing optical fiber adopts the U-shaped plane measurement method, the leakage detection signal obtained has more than one abnormal point. The sensing optical fiber obtains signals at 13.6m and 23.8m respectively. The corresponding coordinates of the pipeline position calculated by the distributed optical fiber leakage detection system are [3.8, 0.8] and [3.6, 0.4], and the positioning error is within 0.6m.

[0088] See also Figure 6 The optical fiber grid-shaped laying detection signal diagram. When the sensing optical fiber adopts the grid-type plane measurement method, the sensing optical fiber is laid on the pipeline wall. The overall optical fiber layout is a 1m×5m rectangle, and the optical fiber coverage area is about 47100cm 2, about 100 grids are formed on the pipeline surface, and four signal abnormal points are obtained, corresponding to the sensing fiber positions of 12.9m, 23.3m, 48.2m and 48.4m. Then, the distributed optical fiber leakage detection system is used to obtain the coordinates of the abnormal point positions as [3.1, 0.8], [3.1, 0.4], [3.2, 0.8],

[0089] [3.2,0.6], according to the calculation results, the leakage area is located in the rectangle from 3.1m to 3.2, and the positioning error is less than 0.2m compared with the actual leakage point at 3.2m.

[0090] Through the above comparison, the present invention collects temperature signals and vibration frequency signals when there is no leakage on the pipeline surface, determines the normal value signal of the signal when there is no leakage; changes the temperature and vibration frequency signals during leakage into abnormal signal values; compares the abnormal value with the normal value, determines the mutation point of temperature and vibration, and locates the leakage point of the pipeline network more accurately, and combines with optical fiber equipment and dynamic testing equipment to determine the hazard source, and realizes real-time early warning of temperature and vibration data in the pipeline; and according to the dynamic testing equipment, realizes the function of analyzing and early warning the location of the hazard source, hazard level, historical data, etc. along the pipeline network, thereby realizing dynamic testing.

[0091] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. In addition, it should be understood that although this specification is described in accordance with the implementation mode, this narrative mode of the specification is only for the sake of clarity, and those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A distributed optical fiber leakage detection method, characterized in that: The steps include: S1: Based on the parameters of pipeline length and diameter, a spatial grid-based sensing scheme is established. The sensing optical fiber is laid out in a grid shape along the horizontal and vertical planes, and then covered on the pipeline surface. S2: According to the grid-like laying plan of optical fiber, a distributed optical fiber detection system for underground pipe network temperature and vibration is built to collect environmental signal data; S3: Establishing an environmental signal law analysis model under normal working conditions; S4: Real-time acquisition of environmental signal data through the distributed optical fiber leakage detection system, and calculation of possible pipeline leakage locations based on signal anomalies; S5: Analyze the pipeline temperature and vibration signal data at the location where leakage may occur, compare the data of the abnormal signal point, and determine whether leakage occurs.

2. The distributed optical fiber leakage detection method according to claim 1, characterized in that: The specific process of establishing the environmental signal law analysis model under normal working conditions in step S3 includes: S31: Covering the detection pipeline with a grid-shaped sensing optical fiber; S32: According to actual engineering cases, characteristic values ​​of temperature and vibration data of the pipeline under historical leakage conditions and characteristic values ​​of temperature and vibration data under normal conditions are obtained; S33: The characteristic values ​​of the data under normal working conditions are compared with the characteristic values ​​of the comparative data under leakage working conditions, the data noise is eliminated, and an environmental signal law analysis model is established.

3. The distributed optical fiber leakage detection method according to claim 2, characterized in that: The specific steps of calculating the possible leakage position of the pipeline in step S4 include: S41: according to the temperature and vibration signal data under normal working conditions, the difference of the data characteristic values ​​under normal working conditions is calculated and stored in the historical working condition database; S42: Obtaining the optical fiber detection signal in real time, comparing the data difference of the optical fiber detection point with the difference in the historical working condition database, if the comparison meets the standard of normal working condition, the sensor output result is normal, if the comparison does not meet the standard of normal working condition, calculating the abnormal value of the output signal, and determining the optical fiber detection signal corresponding to the abnormal value; S43: According to the abnormal optical fiber detection signal, the mutation point of the temperature and vibration signal is determined, and then the actual position of the underground pipeline in the corresponding grid area is calculated through the grid points.

4. The distributed optical fiber leakage detection method according to claim 3, characterized in that: The specific process of step S5 includes: S51: collecting data of abnormal signal points of temperature and vibration of the pipeline where leakage may occur and eliminating data noise; S52: According to the database of historical working conditions, determine the leakage medium and accident model in the pipeline, model and simulate the pipeline leakage accident, and establish a leakage accident model data set; S53: collecting and processing a pipeline leakage accident model data set, calculating the temperature-time and vibration frequency-time data of the pipeline and the surrounding space after the pipeline leakage accident occurs through finite element simulation, and determining the maximum value of the temperature and vibration changes around the pipeline; S54: Analyze the environmental signal using the principal component analysis method to remove the environmental noise data in the maximum values ​​of temperature and vibration changes; S55: Compare the environmental characteristic information with the environmental signal law analysis model under normal working conditions to determine whether leakage occurs.

5. A device using any one of the distributed optical fiber leakage detection methods of claims 1-4, characterized in that: The hardware part of the distributed optical fiber leakage detection system includes a distributed optical fiber leakage detection device, that is, a distributed optical fiber temperature measurement host, a computer, a plurality of data amplifiers, a data analysis device, and a dynamic test device; the distributed optical fiber temperature measurement host is connected to the dynamic test device; the dynamic test device is connected to the data amplifier; the distributed optical fiber temperature and vibration detection device is used to collect temperature and vibration data on the optical fiber in the distributed optical fiber temperature measurement host.

6. The device according to claim 5, characterized in that The distributed optical fiber temperature measurement host is connected to a dynamic test device, which includes a test bracket and a test wiring. The test bracket is fixedly mounted on the outer wall of the pipeline to be tested, and the test wiring is mounted on the test bracket. A plurality of S-shaped sleeves are wrapped around the distributed optical fiber temperature and vibration monitoring device. Two adjacent S-shaped sleeves are connected by a fixing device. The sensing optical fiber in the distributed optical fiber leakage detection device is wired along the entire length of the pipeline, and the wiring form of the sensing optical fiber is as follows: the length and diameter parameters of the pipeline are obtained, and the sensing optical fiber is laid on the outermost layer of the pipeline according to the grid plane, covering the entire pipe wall surface, and the grid laying interval is set to a square grid of 0.2m*0.2m.

7. A system using the distributed optical fiber leakage detection method of claims 1-4, characterized in that: It includes a historical working condition database, a sensing optical fiber, a signal preprocessor, a sensing signal database, and a solution module; the signal preprocessor is used to preprocess the collected environmental signals, temperature and vibration signals; the solution module is used to solve and analyze the preprocessed signals with the accident data in the historical working condition database to obtain the accident results; the working process of the system is as follows: the environmental signals, temperature and vibration signals collected by the distributed optical fiber detection system are preprocessed by the signal preprocessor, and then compared with the sensing signals in the sensing signal historical working condition database in the solution module to determine the accident characteristics and output the results; the working process of the system is as follows: S101: collecting optical fiber temperature and vibration data through a distributed optical fiber leakage detection system and preprocessing the data; S102: Identify the pipeline environment signal status, if abnormal, then go to S103; if normal, then return to S101 to continue running the system; S103: Determine the spatial scope and location of the accident impact by comparing the data in the historical operating condition database with the data in the sensor signal database; S104: Based on the result of S103, identify the pipeline in the abnormal area and determine whether leakage occurs.

8. The distributed optical fiber leakage detection system according to claim 7, characterized in that: The specific process of identifying the pipeline environment status in step S102 includes: S1021: Calculate the temperature change value at each position of the optical fiber, process signal characteristics, analyze the vibration spectrum, and analyze the environmental signal at the same time, so as to obtain a feature vector data set of the optical fiber temperature and vibration signal in the area, and calculate it; S1022: Obtain the ambient temperature T' and vibration frequency V' in the pipeline environmental state; obtain the real temperature T and vibration frequency V data of the accident data; calculate the difference under the environment, compare it with the temperature and vibration difference under historical working conditions, and determine the abnormal signal A = (A1, A2, ..., An).

9. The distributed optical fiber leakage detection system according to claim 8, characterized in that: The process of obtaining the feature vector data set in S1021 includes establishing a multidimensional feature vector set: storing the data set obtained during the optical fiber temperature measurement and detection process in the sensor signal database, processing it in combination with the system data obtained by the optical fiber leakage detection system, and performing matrix representation to obtain a multidimensional feature vector set.

10. The distributed optical fiber leakage detection system according to claim 9, characterized in that: In the S1022, the position of the abnormal signal A is determined; the area (A1, A2, ..., Am) where the abnormal signal A is located in the multidimensional feature vector set is determined, by calculating the abnormal point Amin'=minA', where A' represents the multidimensional feature vector set, Amin' is the minimum signal feature vector of the abnormal area A, and the signal feature vector minA' is the location of the leakage point.

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