Water pipeline safety monitoring system and monitoring method based on optical fiber vibration and underwater acoustic sensing

Abstract

The invention discloses a water delivery pipeline safety monitoring system and monitoring method based on optical fiber vibration and underwater acoustic sensing, and relates to the field of optical fiber sensing and water delivery monitoring, and the system comprises a distributed optical fiber acoustic vibration monitoring subsystem which comprises a distributed optical fiber acoustic vibration demodulation device and a distributed optical fiber, the distributed optical fibers are tightly mounted on the outer wall of the pipeline; the interference type quasi-distribution optical fiber hydrophone subsystem comprises an interference type quasi-distribution optical fiber hydrophone demodulation device, an optical fiber hydrophone and an interference type optical fiber, and the optical fiber hydrophone is fixed to the outer wall of the pipeline through a rigid shell; the signal fusion analysis subsystem is used for receiving data of the interference type quasi-distributed optical fiber hydrophone demodulation device and the distributed optical fiber sound wave vibration demodulation device at the same time; the pipeline safety monitoring platform software is used for receiving the data analyzed and identified by the signal fusion analysis subsystem and carrying out visualization processing; and the synchronous time service device is used for carrying out synchronous time service through the standard clock source. The problem of leakage monitoring and positioning in the water conveying pipeline is solved.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber sensing and water delivery monitoring, and in particular to a water delivery pipeline safety monitoring system and a monitoring method based on optical fiber vibration and hydroacoustic sensing. Background Art

[0002] Underground pipeline transportation has the advantages of safety, reliability, large transportation volume, no surface space occupation, and low energy consumption, so it has been widely used. However, water supply pipelines are often buried underground, which makes it difficult to check and deal with them in a timely manner. In the past, water resources were regarded as ordinary resources, so online leakage monitoring was rarely used in engineering construction. There are many leakage problems in urban underground tap water pipe networks. The main monitoring methods currently used include regional meter installation method (metering meter), detection by inspection personnel using special sound transmission tools such as leak listening rods and detectors, and leak detection methods. However, these methods are not suitable for large, long-distance, and high-pressure water pipelines.

[0003] After the pipeline is put into use, it will be affected by the environment and will experience natural aging phenomena such as thermal expansion and contraction, corrosion and rust. At the same time, due to the natural settlement of the surface and backfill foundation and the influence of surrounding construction, the pipeline will have continuous and slow leakage, which is not easy to detect and leads to waste of water resources. If the leakage problem is ignored, for high-pressure water pipelines, it will further increase the risk of bursting and cause serious safety accidents.

[0004] At present, there have been some studies on leakage and early warning of long-distance pressure water pipeline projects, but they are generally based on separate distributed optical fiber sensing and separate electrical hydrophones. Under the principle of single distributed optical fiber vibration sensing, the time interval for sending laser pulses is related to the length of the connected optical fiber (after each pulse is sent, it is necessary to ensure that the scattered light on all lengths has returned before the next optical pulse can be output). Therefore, the frequency response range of the single distributed optical fiber sensing method becomes lower as the distance increases, and there is a problem of limited bandwidth. When using the electrical hydrophone array method for leakage monitoring, all hydrophones need to be collected synchronously (the time synchronization accuracy cannot exceed 1ms). Since the pipeline is underground, especially in the tunnel method, the distance between the two pipeline wells is very long (>1.5km), and the monitoring distance of adjacent hydrophones cannot be fully covered. Therefore, electrical hydrophones must be installed in locations without pipeline wells. At this time, power supply is difficult and the Beidou terminal antenna used for synchronization cannot be extended to the ground, so power supply and synchronization become problems. A separate electrical hydrophone array requires precise synchronization with the external BeiDou system in order to perform relevant analysis. In addition, in the construction of long-distance pipelines, the need for a set of solar power every few hundred meters required for the electrical hydrophone array is often a problem.

[0005] In summary, the existing single distributed fiber optic sensing method has the problem of limited bandwidth, and the single electrical hydrophone array method has the problem of difficult clock synchronization and field power supply. These are factors that restrict the promotion of water monitoring systems. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and to provide a water pipeline safety monitoring system and monitoring method based on optical fiber vibration and hydroacoustic sensing, which integrates φ-OTDR and interferometric hydroacoustic technology, and has both the ability to accurately locate distributed optical fibers and the ability to detect hydroacoustic signals via broadband. At the same time, due to the all-optical method, there is no need to configure a power supply along the entire pipeline and it is not affected by environmental interference. In addition, acoustic verification and other methods are fully applied in data analysis to solve the problem of leak monitoring and positioning in water pipelines.

[0007] The purpose of the present invention is to achieve the following technical solution: a water pipeline safety monitoring system based on optical fiber vibration and hydroacoustic sensing, comprising:

[0008] A distributed optical fiber acoustic wave vibration monitoring subsystem, including a distributed optical fiber acoustic wave vibration demodulation device and a distributed optical fiber, with the optical cable tightly installed on the outer wall of the pipeline;

[0009] An interferometric quasi-distributed optical fiber hydrophone subsystem comprises an interferometric quasi-distributed optical fiber hydrophone demodulation device, an optical fiber hydrophone and an interferometric optical fiber. There are a plurality of optical fiber hydrophones arranged at intervals on the outer wall of a pipeline. Each optical fiber hydrophone is fixed to the outer wall of the pipeline through a rigid shell, and the interferometric optical fiber passes through each rigid shell in sequence.

[0010] A signal fusion analysis subsystem, mounted on a computer with computing power, is used to simultaneously receive data from the interferometric quasi-distributed optical fiber hydrophone demodulation device and the distributed optical fiber acoustic wave vibration demodulation device, align and store the data, and perform analysis and identification;

[0011] Pipeline safety monitoring platform software, installed on the computer, is used to receive the data analyzed and identified by the signal fusion analysis subsystem, perform visualization processing, and display the safety status of each location on the pipeline in real time based on the data; and

[0012] The synchronous timing device synchronizes the timing of the distributed optical fiber acoustic vibration monitoring subsystem and the interferometric quasi-distributed optical fiber hydrophone subsystem through a standard clock source.

[0013] As a further technical solution, the interferometric quasi-distributed fiber optic hydrophone demodulation device uses time division multiplexing to collect signals transmitted from multiple fiber optic hydrophones, and the distributed acoustic wave vibration demodulation device uses phase-sensitive optical reflectometer technology; the distributed fiber optic acoustic wave vibration demodulation device and the interferometric quasi-distributed fiber optic hydrophone demodulation device are both provided with a synchronization signal input interface, and the synchronization signal is used to synchronize the internal sampling signal of the demodulation device; the distributed fiber optic acoustic wave vibration demodulation device has a dual-channel synchronous output capability, which is used to simultaneously access two optical fibers and simultaneously collect vibration signals on the two optical fibers.

[0014] As a further technical solution, the fiber optic hydrophone includes a fiber optic vibration sensing component, a fiber optic coil, a reflector and a flexible sound sensing component arranged in a rigid housing. The fiber optic hydrophone is connected in series in a time-division manner to form a multi-sensor vibration signal measurement, and the fiber optic hydrophone is positioned using an OTDR method; a fiber coiling space is provided in the rigid housing of the fiber optic hydrophone for coiling the excess length of the connected optical fiber in the rigid housing; the distributed optical fiber and the interferometric optical fiber are integrated on an optical cable.

[0015] As a further technical solution, the optical fiber vibration sensing component includes a mechanical resonance component and an optical fiber winding ring tightly fixed to the mechanical resonance component. The rigid shell adopts an optical fiber double-end interface, one end of which is connected to the input light and the other end is connected to the output light and can be cascaded to the next optical fiber hydrophone. The optical fiber outlet of the rigid shell is sealed with glue so that external pulling of the optical fiber will not affect the inside of the optical fiber hydrophone; a vibration reduction area is provided between the optical fiber winding ring and the optical fiber end to prevent the vibration of the connected optical fiber from affecting the internal sensor; the sensing surface of the flexible acoustic sensing component exists only on the side attached to the pipe wall, and only responds to vibration / sound wave information from the pipe wall, and is not affected by sounds from other directions.

[0016] As a further technical solution, the signal fusion analysis subsystem also includes:

[0017] A network interface for simultaneously receiving data from an interferometric quasi-distributed optical fiber hydrophone demodulation device and a distributed optical fiber acoustic wave vibration demodulation device;

[0018] A data synchronization storage module is used to align and store data from the interferometric quasi-distributed optical fiber hydrophone demodulation device and the distributed optical fiber acoustic wave vibration demodulation device at the same time;

[0019] A hydrophone signal recognition module is used to analyze and recognize data from an interferometric quasi-distributed optical fiber hydrophone demodulation device, and provide a sound event recognition type and a hydrophone in which a specific event occurs; and

[0020] The distributed optical fiber signal recognition module is used to analyze and identify the data from the distributed optical fiber acoustic wave vibration demodulation device, and provide the sound event recognition type and the distance position of the specific event relative to the optical fiber outlet of the distributed optical fiber acoustic wave demodulation device.

[0021] A water pipeline safety monitoring method based on optical fiber vibration and hydroacoustic sensing, based on the above-mentioned water pipeline safety monitoring system based on optical fiber vibration and hydroacoustic sensing, comprises the following steps:

[0022] S1: Distributed optical fiber distance calibration is performed on the pipeline to obtain the full-line vibration spatial distribution with the pipeline as the horizontal axis and the spatial sampling rate as the interval;

[0023] S2: Measure the intervals of the fiber optic hydrophones on the pipeline to obtain the multi-point vibration spatial distribution of the entire line with the pipeline as the horizontal axis and the fiber optic hydrophone distance as the interval;

[0024] S3: Sample library establishment and identification, collect sound data under different conditions and events, establish sample library, and form alarm strategies under different events;

[0025] S4: Use the distributed fiber optic acoustic wave vibration demodulation device and the interferometric quasi-distributed fiber optic hydrophone demodulation device to demodulate and obtain the vibration amplitude-time-distance three-dimensional information, determine whether an event has occurred, locate the actual location of the event, compare and judge with the sample library, record and store the obtained event type, and send out an alarm signal.

[0026] As a further technical solution, S1 includes:

[0027] S1.1. Bond a vibration optical cable on each side of the pipeline, and connect one optical fiber core of each of the two vibration optical cables to the optical fiber interface of the optical fiber vibration sensing component;

[0028] S1.2. Use a standard distance measuring device such as a ruler or laser distance meter to measure a distance and gently tap the vibrating optical cable at that location. Map the optical fiber length displayed by the optical fiber vibration time domain signal on the pipeline safety monitoring platform software with the actual pipeline distance.

[0029] S1.3. Complete the full distance calibration of the two vibration optical cables and obtain the full-line vibration spatial distribution with the pipeline as the horizontal axis and the spatial sampling rate as the interval.

[0030] As a further technical solution, S2 includes:

[0031] S2.1. Use OTDR to measure the actual position and length of the optical fiber of each optical fiber hydrophone;

[0032] S2.2. Connect the fiber optic hydrophone to the interferometric quasi-distributed fiber optic hydrophone demodulation device, adjust the time interval of time division multiplexing, and ensure that the fiber optic hydrophone signal acquisition is in the optimal position;

[0033] S2.3. Use standard distance measuring devices such as a ruler and laser rangefinder to measure the distance of the hydrophone on the pipeline and map the fiber optic hydrophone number to the actual pipeline distance;

[0034] S2.4. Complete the distance calibration of all fiber optic hydrophones to obtain the multi-point vibration spatial distribution of the entire line with the pipeline as the horizontal axis and the fiber optic hydrophone distance as the interval.

[0035] As a further technical solution, S3 includes:

[0036] S3.1. Collect and record sound data under quiet conditions (the fan in the pipeline is turned off), mark and store them in the negative sample library;

[0037] S3.2. Collect sound data from non-quiet conditions or uncertain interference sources (such as rain), mark them and store them in the negative sample library;

[0038] S3.3. Collect sound data of known interference events (such as ventilation fan sound, pile driving sound, subway passing sound), classify and mark them, and store them in the positive sample library;

[0039] S3.4. Collect sound data of known simulated leakage events (such as the sound of dripping water in pipes and the sound of flushing pipes), classify and mark them, and store them in the positive sample library;

[0040] S3.5, establish a sample library and use convolutional neural network CNN for training;

[0041] S3.6. Collect correct data and conduct event identification;

[0042] S3.7. An alarm strategy is formed based on the identified events. If the event is a short-term large signal event (such as knocking), it will be reported in time. If it is a continuous small signal event (such as a small leak), it will be given after multiple judgments.

[0043] As a further technical solution, S4 includes:

[0044] S4.1. After completing the calibration of the distributed optical fiber distance and the optical fiber hydrophone deployment interval measurement calibration, start the system to enter the normal working mode;

[0045] S4.2, the distributed optical fiber acoustic wave vibration demodulation device obtains the three-dimensional information of vibration amplitude A1-time t-distance d by phase demodulating the scattered signal returned from the distributed sensing optical fiber;

[0046] S4.3, the interferometric quasi-distributed optical fiber hydrophone demodulation device demodulates the interference signal returned from the optical fiber hydrophone to obtain the three-dimensional information of vibration amplitude A2-time t-distance d;

[0047] S4.4, performing data cleaning on the three-dimensional information of vibration amplitude A1-time t-distance d to obtain the three-dimensional information of vibration amplitude B1-time t-distance d, and performing data cleaning on the three-dimensional information of vibration amplitude A2-time t-distance d to obtain the three-dimensional information of vibration amplitude B2-time t-distance d;

[0048] S4.5, compare the energy change between the vibration amplitude B1-time t-distance d and its body noise, determine whether an event occurs, and identify it to obtain E1-time t1-distance d1;

[0049] S4.6. Compare the relationship between the vibration amplitude B2-time t-distance d and its body noise to determine whether an event has occurred; and perform correlation analysis on two adjacent fiber optic hydrophones where the event occurred to locate the actual event location E2-time t2-distance d2;

[0050] S4.7. Determine whether |t1-t2| is less than a certain range and |d1-d2| is also less than a certain range. If so, it is considered to be caused by the same event and the review is passed;

[0051] S4.8. Use machine learning methods to compare with the data in the sample library to derive the event type;

[0052] S4.9. Record and store the time, location, and type of event.

[0053] The beneficial effects of the present invention are:

[0054] 1. The present invention adopts a distributed optical fiber combined with an optical fiber hydrophone, utilizes the high bandwidth of the optical fiber hydrophone to make up for the insufficient bandwidth of the distributed optical fiber, utilizes the sensing optical cable of the distributed optical fiber as the transmission optical cable between the optical fiber hydrophones, and utilizes the advantages of the optical fiber hydrophone's fast optical transmission speed and natural synchronization, thus forming a continuous monitoring system with no blind spots, broadband sound source information input, dual-technical system composite judgment, low false alarm rate, and high reliability;

[0055] 2. The present invention combines distributed fiber optic vibration sensing (φ-OTDR principle) with a quasi-distributed interferometric fiber optic hydrophone array to jointly detect sound in the pipeline, and synchronizes the optical cable signal attached to the pipe wall (used for distributed fiber optic vibration sensing) and the fiber optic hydrophone signal (used for quasi-distributed array sensing) in time and space, effectively solving the shortcomings of the traditional single distributed fiber optic vibration sensing method (the bandwidth of distributed fiber optic vibration sensing is limited under long-distance conditions) or the shortcomings of the single hydrophone monitoring method (poor positioning accuracy), greatly improving the efficiency and accuracy of pipeline leakage monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic diagram of the structure of the present invention.

[0057] Figure 2 It is a schematic diagram of the process of the present invention.

[0058] Figure 3 It is a schematic diagram of the structure of the pipeline and the optical fiber hydrophone assembled according to the present invention.

[0059] Explanation of the reference numerals: pipeline 1, rigid shell 2, fiber coil space 3, optical fiber vibration sensing component 4, flexible acoustic sensing component 5, optical cable 6, vibration reduction area 7, distributed optical fiber acoustic wave vibration monitoring subsystem 10, interferometric quasi-distributed optical fiber hydroacoustic subsystem 20, signal fusion analysis subsystem 30, pipeline safety monitoring platform software 40, synchronous timing device 50. DETAILED DESCRIPTION

[0060] The present invention will be described in detail below with reference to the accompanying drawings:

[0061] Embodiment 1: As attached Figures 1 to 3 As shown, a water pipeline safety monitoring system based on optical fiber vibration and hydroacoustic sensing includes a pipeline 1, a rigid shell 2, a fiber coil space 3, an optical fiber vibration sensing component 4, a flexible acoustic sensing component 5, an optical cable 6, a vibration reduction area 7, a distributed optical fiber acoustic wave vibration monitoring subsystem 10, an interferometric quasi-distributed optical fiber hydroacoustic subsystem 20, a signal fusion analysis subsystem 30, a pipeline safety monitoring platform software 40 and a synchronous timing device 50.

[0062] Reference Figure 1 , 3The distributed optical fiber acoustic vibration monitoring subsystem 10 includes a distributed optical fiber acoustic vibration demodulation device and a distributed optical fiber. The distributed optical fiber is tightly installed on the outer wall of the pipeline 1 (the pipeline 1 can be a ductile iron pipeline, a steel pipe, or other metal pipelines). The distributed acoustic vibration demodulation device adopts phase-sensitive optical reflectometer technology. Further, the distributed optical fiber acoustic vibration demodulation device includes a narrow linewidth laser, an optical fiber beam splitter, an acousto-optic modulator, a pulsed erbium-doped fiber amplifier (pulsed EDFA), an optical fiber circulator, a Raman pump laser, an optical fiber wavelength division multiplexer, a polarization classification module, an optical fiber coupler, and an optoelectronic converter.

[0063] The interferometric quasi-distributed optical fiber hydrophone subsystem 20 includes an interferometric quasi-distributed optical fiber hydrophone demodulation device, an optical fiber hydrophone, and an interferometric optical fiber. There are a plurality of optical fiber hydrophones, which are arranged at intervals on the outer wall of the pipeline 1. Each optical fiber hydrophone is fixed to the outer wall of the pipeline 1 through a rigid shell 2, and the interferometric optical fiber passes through each rigid shell 2 in sequence. Figure 3 As shown, the fiber optic hydrophone includes a fiber optic vibration sensing component 4, a fiber optic coil, a reflector and a flexible sound sensing component 5 arranged in a rigid housing 2. The fiber optic hydrophone is connected in series in a time-division manner to form a multi-sensor vibration signal measurement, and the fiber optic hydrophone is positioned in an OTDR manner. A fiber coiling space 3 is provided in the rigid housing 2 of the fiber optic hydrophone, and the excess length of the connected fiber optic can be coiled in the rigid housing 2. Preferably, the distributed optical fiber and the interferometric optical fiber can be integrated on an optical cable 6 (so that the sensing optical cable of the distributed optical fiber acts as a transmission optical cable between the fiber optic hydrophones, which has a higher degree of integration and reduces the manufacturing cost), or the distributed optical fiber and the interferometric optical fiber can also be arranged on different optical cables.

[0064] The interferometric quasi-distributed fiber optic hydrophone demodulation device uses time division multiplexing to collect signals transmitted back from multiple fiber optic hydrophones, and can achieve multiplexing of multiple channels with fewer optical fibers. Furthermore, the distributed fiber optic acoustic wave vibration demodulation device and the interferometric quasi-distributed fiber optic hydrophone demodulation device are both provided with a synchronization signal input interface, and the synchronization signal can synchronize the internal sampling signal of the demodulation device. The synchronization signal can be the Beidou PPS signal or the synchronization signal transmitted from other systems. The distributed fiber optic acoustic wave vibration demodulation device has a dual-channel synchronous output capability, and can be connected to two optical fibers at the same time, and simultaneously collect vibration signals on the two optical fibers. Furthermore, the interferometric quasi-distributed fiber optic hydrophone demodulation device includes a narrow linewidth laser, an optical fiber beam splitter, a pulsed erbium-doped fiber amplifier (pulse EDFA), an optoelectronic converter, a signal amplification module, a signal generation module, a signal demodulation module, and an optical fiber coupler.

[0065] like Figure 3As shown, the optical fiber vibration sensing component 4 includes a mechanical resonance component and an optical fiber winding ring tightly fixed to the mechanical resonance component. The rigid housing 2 adopts an optical fiber double-end interface, one end of which is connected to the input light and the other end is connected to the output light and can be cascaded to the next optical fiber hydrophone. The optical fiber outlet of the rigid housing 2 is sealed with glue so that the external pulling of the optical fiber will not affect the inside of the optical fiber hydrophone. A vibration reduction area 7 is provided between the optical fiber winding ring and the optical fiber outlet to prevent the vibration of the connected optical fiber from affecting the internal sensor; the sensing surface of the flexible sound sensing component 5 only exists on the side attached to the wall of the pipeline 1, and only responds to the vibration / sound wave information from the wall of the pipeline 1, and is not affected by the sound from other directions.

[0066] The signal fusion analysis subsystem 30 (including the signal fusion analysis algorithm software, carried / installed on a computer with computing power, including but not limited to an industrial computer, a server or other equipment with computing power) can simultaneously receive data from the interferometric quasi-distributed optical fiber hydrophone demodulation device and the distributed optical fiber acoustic wave vibration demodulation device, align and store them, and perform analysis and identification. Further, the signal fusion analysis subsystem 30 also includes:

[0067] A network interface capable of simultaneously receiving data from an interferometric quasi-distributed optical fiber hydrophone demodulation device and a distributed optical fiber acoustic wave vibration demodulation device;

[0068] A data synchronization storage module is capable of aligning and storing data from the interferometric quasi-distributed optical fiber hydrophone demodulation device and the distributed optical fiber acoustic wave vibration demodulation device at the same time;

[0069] A hydrophone signal recognition module is capable of analyzing and identifying data from an interferometric quasi-distributed optical fiber hydrophone demodulation device, providing a sound event recognition type and which hydrophone the specific event occurred in; and

[0070] The distributed optical fiber signal recognition module can analyze and identify the data from the distributed optical fiber acoustic wave vibration demodulation device, and provide the sound event recognition type and the distance position of the specific event relative to the optical fiber outlet of the distributed optical fiber acoustic wave demodulation device.

[0071] Furthermore, the pipeline safety monitoring platform software 40 is also installed on the computer, which can receive the data analyzed and identified by the signal fusion analysis subsystem 30, and perform visualization processing, and display the safety status of each position on the pipeline 1 in real time according to the data. The pipeline safety monitoring platform software includes interfaces such as pipeline layout GIS interface, pipeline route mark, pipeline well mark, pipeline leakage alarm, pipeline vibration alarm, equipment management, optical fiber vibration time domain signal, optical fiber vibration frequency domain signal, hydrophone vibration time domain signal, hydrophone vibration frequency domain signal, and signal time-space synchronous compound.

[0072] The synchronous timing device 50 synchronizes the distributed optical fiber acoustic vibration monitoring subsystem 10 and the interferometric quasi-distributed optical fiber hydrophone subsystem 20 through a standard clock source (using Beidou timing or other standard clock sources for timing), and has a network timing function.

[0073] Embodiment 2: A water pipeline safety monitoring method based on optical fiber vibration and hydroacoustic sensing, based on the water pipeline safety monitoring system based on optical fiber vibration and hydroacoustic sensing described in Embodiment 1, comprises the following steps:

[0074] S1: Distributed optical fiber distance calibration is performed on pipeline 1 to obtain the full-line vibration spatial distribution with pipeline 1 as the horizontal axis and the spatial sampling rate as the interval.

[0075] Furthermore, the above S1 also includes:

[0076] S1.1. Bond a vibration optical cable to each side of the pipeline 1, and connect one optical fiber core of each of the two vibration optical cables to the optical fiber interface of the optical fiber vibration sensing component 4.

[0077] S1.2. Use a standard distance measuring device such as a ruler or a laser distance meter to measure a distance, and gently tap the vibrating optical cable at that location, and map the optical fiber length displayed by the optical fiber vibration time domain signal on the pipeline safety monitoring platform software 40 with the actual pipeline distance.

[0078] S1.3. Complete the full distance calibration of the two vibration optical cables and obtain the full-line vibration spatial distribution with pipeline 1 as the horizontal axis and the spatial sampling rate as the interval.

[0079] S2: Measure the intervals of the fiber optic hydrophones on pipeline 1 to obtain the multi-point vibration spatial distribution of the entire line with pipeline 1 as the horizontal axis and the fiber optic hydrophone distance as the interval.

[0080] The above S2 also includes:

[0081] S2.1. Use OTDR to measure the actual location and length of the optical fiber of each optical fiber hydrophone.

[0082] S2.2. Connect the fiber optic hydrophone to the interferometric quasi-distributed fiber optic hydrophone demodulation device, adjust the time interval of time division multiplexing, and ensure that the fiber optic hydrophone signal acquisition is in the optimal position.

[0083] S2.3. Use standard distance measuring devices such as a ruler and laser rangefinder to measure the distance of the hydrophone on the pipeline and map the fiber optic hydrophone number to the actual pipeline distance.

[0084] S2.4. Complete the distance calibration of all fiber optic hydrophones to obtain the multi-point vibration spatial distribution of the entire line with pipeline 1 as the horizontal axis and the fiber optic hydrophone distance as the interval.

[0085] S3: Sample library establishment and identification, collect sound data under different conditions and events, establish a sample library, and form alarm strategies under different events.

[0086] Specifically, the above S3 also includes:

[0087] S3.1. Collect sound data under quiet conditions (the fan in the pipeline is turned off at this time), mark it and store it in the negative sample library.

[0088] S3.2. Collect sound data under non-quiet conditions or with uncertain interference sources (such as rain), mark them and store them in the negative sample library.

[0089] S3.3. Collect sound data of known interference events (such as ventilation fan sound, overhead pile driving sound, subway passing sound), classify and mark them, and store them in the positive sample library.

[0090] S3.4. Collect sound data of known simulated leakage events (such as the sound of dripping water in pipes and the sound of flushing pipes), classify and mark them, and store them in the positive sample library.

[0091] S3.5. Establish a sample library and use convolutional neural network (CNN) for training.

[0092] S3.6. Collect correct data and conduct event identification.

[0093] S3.7. An alarm strategy is formed based on the identified events. If the event is a short-term large signal event (such as knocking), it will be reported in time. If it is a continuous small signal event (such as a small leak), it will be given after multiple judgments.

[0094] S4: Use the distributed fiber optic acoustic wave vibration demodulation device and the interferometric quasi-distributed fiber optic hydrophone demodulation device to demodulate and obtain the vibration amplitude-time-distance three-dimensional information, determine whether an event has occurred, locate the actual location of the event, compare and judge with the sample library, record and store the obtained event type, and send out an alarm signal.

[0095] The above S4 also includes:

[0096] S4.1. After completing the calibration of the distributed optical fiber distance and the optical fiber hydrophone deployment interval measurement calibration, start the system and enter the normal working mode.

[0097] S4.2. The distributed optical fiber acoustic wave vibration demodulation device obtains the three-dimensional information of vibration amplitude A1(t,d)-time-distance by phase demodulating the scattered signal returned from the distributed sensing optical fiber.

[0098] S4.3. The interferometric quasi-distributed fiber optic hydrophone demodulation device demodulates the interference signal returned from the fiber optic hydrophone to obtain the vibration amplitude A2(t,d)-time-distance three-dimensional information.

[0099] S4.4. Perform data cleaning on the three-dimensional information of vibration amplitude A1(t, d)-time-distance to obtain the three-dimensional information of vibration amplitude B1(t, d)-time-distance, and perform data cleaning on the three-dimensional information of vibration amplitude A2(t, d)-time-distance to obtain the three-dimensional information of vibration amplitude B2(t, d)-time-distance.

[0100] S4.5. Compare the energy change between the vibration amplitude B1(t, d)-time-distance and its body noise, determine whether an event occurs, and identify it to obtain E1(t1, d1).

[0101] S4.6. Compare the relationship between the vibration amplitude B2(t, d)-time-distance and its body noise to determine whether an event has occurred; and perform correlation analysis on the two adjacent fiber optic hydrophones where the event occurred to locate the actual location of the event E2(t2, d2).

[0102] S4.7. Determine whether |t1-t2| is less than a certain range and |d1-d2| is also less than a certain range. If so, it is considered to be caused by the same event and the review is passed.

[0103] S4.8. Use machine learning methods to compare data with the sample library to determine the event type.

[0104] S4.9. Record and store the time, location, and type of event.

[0105] The present invention combines distributed optical fiber vibration sensing (φ-OTDR principle) with a quasi-distributed interferometric optical fiber hydrophone array to jointly detect sound in the pipeline, and synchronizes the optical cable signal (used for distributed optical fiber vibration sensing) and the optical fiber hydrophone signal (used for quasi-distributed array sensing) attached to the pipe wall in time and space, effectively solving the shortcomings of the traditional single distributed optical fiber vibration sensing method (limited bandwidth of distributed optical fiber vibration sensing under long-distance conditions) or the shortcomings of the single hydrophone monitoring method (poor positioning accuracy), greatly improving the efficiency and accuracy of pipeline leakage monitoring.

[0106] The monitoring of PCCP broken wires using distributed optical fiber acoustic wave sensing combined with interferometric optical fiber sensors is similar to the technical principle of the present invention, and the basic principle of optical interference is similar.

[0107] But the difference is:

[0108] 1. The present invention makes the sensing optical fiber part of the interference hydrophone into a point-type vibration sensing device with a unique vibration structure (while the PCCP broken wire monitoring still uses a whole sensing optical cable).

[0109] 2. The interferometric hydrophone in the present invention adopts a time-division multiplexing method, and multiple hydrophones form an array, and leak location and identification are performed through a correlation method (however, PCCP broken wire monitoring cannot be located through a correlation method).

[0110] 3. In the signal fusion analysis of the present invention, the distributed optical fiber acoustic vibration monitoring subsystem and the interferometric quasi-distributed optical fiber hydrophone subsystem are strictly synchronized in time and space (while the PCCP broken wire monitoring is mainly synchronized in time).

[0111] It is understandable that, for those skilled in the art, any equivalent replacement or change to the technical solution and inventive concept of the present invention should fall within the protection scope of the claims attached to the present invention.

Claims

1. A water pipeline safety monitoring system based on optical fiber vibration and hydroacoustic sensing, characterized in that: include: A distributed optical fiber acoustic wave vibration monitoring subsystem (10) comprises a distributed optical fiber acoustic wave vibration demodulation device and a distributed optical fiber, wherein the distributed optical fiber is tightly mounted on the outer wall of the pipeline (1); An interferometric quasi-distributed optical fiber hydrophone subsystem (20) comprises an interferometric quasi-distributed optical fiber hydrophone demodulation device, an optical fiber hydrophone and an interferometric optical fiber, wherein the optical fiber hydrophones are provided in a plurality and arranged at intervals on the outer wall of a pipeline (1), each optical fiber hydrophone is fixed to the outer wall of the pipeline (1) via a rigid housing (2), and the interferometric optical fiber passes through each rigid housing (2) in sequence; A signal fusion analysis subsystem (30), mounted on a computer with computing power, is used to simultaneously receive data from the interferometric quasi-distributed optical fiber hydrophone demodulation device and the distributed optical fiber acoustic wave vibration demodulation device, align and store the data, and perform analysis and identification; The pipeline safety monitoring platform software (40) is installed on the computer and is used to receive the data analyzed and identified by the signal fusion analysis subsystem (30), perform visualization processing, and display the safety status of each position on the pipeline (1) in real time based on the data; as well as The synchronous timing device (50) performs synchronous timing on the distributed optical fiber acoustic wave vibration monitoring subsystem (10) and the interferometric quasi-distributed optical fiber hydrophone subsystem (20) through a standard clock source.

2. The water pipeline safety monitoring system based on optical fiber vibration and hydroacoustic sensing according to claim 1 is characterized in that: The interferometric quasi-distributed optical fiber hydrophone demodulation device collects signals transmitted from a plurality of optical fiber hydrophones in a time division multiplexing manner, and the distributed acoustic wave vibration demodulation device adopts phase sensitive optical reflectometer technology; The distributed optical fiber acoustic wave vibration demodulation device and the interferometric quasi-distributed optical fiber hydroacoustic demodulation device are both provided with a synchronization signal input interface, and the synchronization signal is used to synchronize the internal sampling signal of the demodulation device; the distributed optical fiber acoustic wave vibration demodulation device has a dual-channel synchronous output capability, which is used to simultaneously access two optical fibers and simultaneously collect vibration signals on the two optical fibers.

3. The water pipeline safety monitoring system based on optical fiber vibration and hydroacoustic sensing according to claim 1 is characterized in that: The fiber optic hydrophone comprises a fiber optic vibration sensing component (4), a fiber optic coil, a reflector and a flexible sound sensing component (5) arranged in a rigid housing (2); the fiber optic hydrophone is connected in series in a time division manner to form a multi-sensor vibration signal measurement, and the fiber optic hydrophone is positioned in an OTDR manner; a fiber coiling space (3) is provided in the rigid housing (2) of the fiber optic hydrophone for coiling the excess length of the connected fiber optic into the rigid housing (2); the distributed optical fiber and the interferometric optical fiber are integrated on an optical cable (6).

4. The water pipeline safety monitoring system based on optical fiber vibration and hydroacoustic sensing according to claim 3 is characterized in that: The optical fiber vibration sensing component (4) comprises a mechanical resonance component and an optical fiber winding ring tightly fixed to the mechanical resonance component. The rigid housing (2) adopts an optical fiber double-end interface mode, one end of which is connected to input light and the other end is connected to output light and can be cascaded to the next optical fiber hydrophone. The optical fiber outlet of the rigid housing (2) is sealed with glue. A vibration reduction area (7) is provided between the optical fiber winding ring and the optical fiber end. The sensing surface of the flexible acoustic sensing component (5) exists only on the side attached to the wall of the pipeline (1), and only responds to vibration / sound wave information from the wall of the pipeline (1), and is not affected by sounds from other directions.

5. The water pipeline safety monitoring system based on optical fiber vibration and hydroacoustic sensing according to claim 1 is characterized in that: The signal fusion analysis subsystem (30) further includes: A network interface for simultaneously receiving data from an interferometric quasi-distributed optical fiber hydrophone demodulation device and a distributed optical fiber acoustic wave vibration demodulation device; A data synchronization storage module is used to align and store data from the interferometric quasi-distributed optical fiber hydrophone demodulation device and the distributed optical fiber acoustic wave vibration demodulation device at the same time; A hydrophone signal recognition module is used to analyze and recognize data from an interferometric quasi-distributed optical fiber hydrophone demodulation device, and provide a sound event recognition type and a hydrophone in which a specific event occurs; and The distributed optical fiber signal recognition module is used to analyze and identify the data from the distributed optical fiber acoustic wave vibration demodulation device, and provide the sound event recognition type and the distance position of the specific event relative to the optical fiber outlet of the distributed optical fiber acoustic wave demodulation device.

6. A water pipeline safety monitoring method based on optical fiber vibration and hydroacoustic sensing, based on the water pipeline safety monitoring system based on optical fiber vibration and hydroacoustic sensing as described in any one of claims 1 to 5, characterized in that: The following steps are involved: S1: Distributed optical fiber distance calibration is performed on the pipeline (1) to obtain the full-line vibration spatial distribution with the pipeline (1) as the horizontal axis and the spatial sampling rate as interval; S2: measuring the intervals of the fiber optic hydrophones on the pipeline (1) to obtain the spatial distribution of multi-point vibration along the entire pipeline with the pipeline (1) as the horizontal axis and the distance of the fiber optic hydrophones as the intervals; S3: Sample library establishment and identification, collect sound data under different conditions and events, establish sample library, and form alarm strategies under different events; S4: Use the distributed fiber optic acoustic wave vibration demodulation device and the interferometric quasi-distributed fiber optic hydrophone demodulation device to demodulate and obtain the vibration amplitude-time-distance three-dimensional information, determine whether an event has occurred, locate the actual location of the event, compare and judge with the sample library, record and store the obtained event type, and send out an alarm signal.

7. The water pipeline safety monitoring method based on optical fiber vibration and hydroacoustic sensing according to claim 6 is characterized in that: The S1 includes: S1.

1. Bond a vibration optical cable to each side of the pipeline (1), and connect one optical fiber core of each of the two vibration optical cables to the optical fiber interface of the optical fiber vibration sensing component (4); S1.

2. Use a standard distance measuring device to measure a distance, and gently tap the vibrating optical cable at that location, and map the optical fiber length displayed by the optical fiber vibration time domain signal on the pipeline safety monitoring platform software (40) with the actual pipeline distance; S1.

3. Complete the full distance calibration of the two vibration optical cables and obtain the full-line vibration spatial distribution with the pipeline (1) as the horizontal axis and the spatial sampling rate as the interval.

8. The water pipeline safety monitoring method based on optical fiber vibration and hydroacoustic sensing according to claim 6 is characterized by: The S2 includes: S2.

1. Use OTDR to measure the actual position and length of the optical fiber of each optical fiber hydrophone; S2.

2. Connect the fiber optic hydrophone to the interferometric quasi-distributed fiber optic hydrophone demodulation device, adjust the time interval of time division multiplexing, and ensure that the fiber optic hydrophone signal acquisition is in the optimal position; S2.

3. Use a standard distance measuring device to measure the distance of the hydrophone on the pipeline and map the fiber optic hydrophone number to the actual pipeline distance; S2.

4. Complete the distance calibration of all fiber optic hydrophones to obtain the multi-point vibration spatial distribution of the entire line with the pipeline (1) as the horizontal axis and the fiber optic hydrophone distance as the interval.

9. The water pipeline safety monitoring method based on optical fiber vibration and hydroacoustic sensing according to claim 6 is characterized in that: The S3 includes: S3.

1. Collect and mark sound data in quiet conditions and store them in the negative sample library; S3.

2. Collect sound data from non-quiet conditions or uncertain interference sources, mark them and store them in the negative sample library; S3.3, collect sound data of known interference events, classify and mark them, and store them in the positive sample library; S3.

4. Collect sound data of known simulated leakage events, classify and mark them, and store them in the positive sample library; S3.5, establish a sample library and use convolutional neural network CNN for training; S3.

6. Collect correct data and conduct event identification; S3.

7. An alarm strategy is formed based on the identified events. If the event is a short-term large-signal event, it is reported in time. If it is a continuous small-signal event, it is given after multiple judgments.

10. The water pipeline safety monitoring method based on optical fiber vibration and hydroacoustic sensing according to claim 6 is characterized in that: The S4 includes: S4.

1. After completing the calibration of the distributed optical fiber distance and the optical fiber hydrophone deployment interval measurement calibration, start the system to enter the normal working mode; S4.2, the distributed optical fiber acoustic wave vibration demodulation device obtains the three-dimensional information of vibration amplitude A1-time t-distance d by phase demodulating the scattered signal returned from the distributed sensing optical fiber; S4.3, the interferometric quasi-distributed optical fiber hydrophone demodulation device demodulates the interference signal returned from the optical fiber hydrophone to obtain the three-dimensional information of vibration amplitude A2-time t-distance d; S4.4, performing data cleaning on the three-dimensional information of vibration amplitude A1-time t-distance d to obtain the three-dimensional information of vibration amplitude B1-time t-distance d, and performing data cleaning on the three-dimensional information of vibration amplitude A2-time t-distance d to obtain the three-dimensional information of vibration amplitude B2-time t-distance d; S4.5, compare the energy change between the vibration amplitude B1-time t-distance d and its body noise, determine whether an event occurs, and identify it to obtain E1-time t1-distance d1; S4.

6. Compare the relationship between the vibration amplitude B2-time t-distance d and its body noise to determine whether an event has occurred; and perform correlation analysis on two adjacent fiber optic hydrophones where the event occurred to locate the actual event location E2-time t2-distance d2; S4.

7. Determine whether |t1-t2| is less than a certain range and |d1-d2| is also less than a certain range. If so, it is considered to be caused by the same event and the review is passed; S4.

8. Use machine learning methods to compare with the data in the sample library to derive the event type; S4.

9. Record and store the time, location, and type of event.

Images