A distributed optical fiber sensing system for PCCP pipeline broken wire detection

Abstract

The utility model discloses a distributed optical fiber sensing system for detecting broken wires in PCCP pipelines. The distributed optical fiber sensing system for detecting broken wires in PCCP pipelines includes an upstream photosensitive path, a downstream sensor light path, a bidirectional combiner, a sensor optical cable, a synchronous trigger module, a data acquisition module, a signal processing module, and an alarm and control host. The system determines whether a broken wire event occurs based on the rich high-frequency information of the link detected by the downstream sensor light path. When the characteristic information of the broken wire signal is included, the broken wire event is located and calculated when the link in the upstream photosensitive path is detected to obtain the broken wire position. The utility model reduces the pressure on the system to process the amount of data, solves the restrictive relationship between the system monitoring distance and the detection frequency in distributed optical fiber sensing, improves the accuracy of PCCP broken wire detection, and reduces the system positioning error.

Description

Technical Field

[0001] The utility model relates to the field of optical fiber sensors, in particular to a distributed optical fiber sensing system for detecting broken wires in PCCP pipelines. Background Art

[0002] According to statistics of PCCP burst accidents at home and abroad, wire breakage (referred to as wire breakage) is the main cause of pipe bursts. During the operation of PCCP, pipe bursts are sudden and catastrophic, and the economic losses and social security hazards caused by them are unpredictable. Studies have shown that the number of broken wires, the location of broken wires, the initial parameters of PCCP design, and the maximum pressure that the pipeline may bear during operation play a key role in the damage and failure of PCCP. Most PCCPs will experience a relatively slow destruction process after wire breakage: the pipeline is subjected to excessive pressure during continuous operation, the protective layer gradually cracks, and the annularly wound prestressed steel wire is exposed to the air, causing the steel wire to corrode and break. After the prestressed steel wire breaks, the pressure on the pipeline is transferred to the steel cylinder, causing the pipe core to crack, and finally the steel cylinder is also exposed to the air and corroded, resulting in PCCP bursts. Therefore, effective monitoring of wire breakage during PCCP operation, timely grasping the number of broken wires in pipelines at different positions, and formulating appropriate pipeline maintenance plans based on this can effectively avoid pipe bursts.

[0003] During the repair process of PCCP, it is necessary to conduct local excavation of the pipeline buried deep in the soil to find the damaged location for reinforcement and repair. This process consumes a lot of manpower, material resources, and financial resources, and there is a certain degree of danger. Accurately and quickly locating the broken wire position of the pipeline during excavation not only saves expenditure costs, but also effectively reduces the possibility of safety accidents during the repair process. To this end, the utility model proposes a distributed optical fiber sensing system for PCCP broken wire detection. Utility Model Content

[0004] The purpose of the utility model is to provide a distributed optical fiber sensing system that can be used for PCCP broken wire detection to solve the problems raised in the above background technology. During the operation of PCCP, the system can dynamically monitor the broken wire status of pipelines at various positions in real time, and has the advantages of high broken wire detection accuracy and small positioning accuracy error, which plays a role in protecting the safe operation of pipelines.

[0005] The technical solution adopted by the utility model to solve the above-mentioned problem is: a distributed optical fiber sensing system for improving the detection of broken wires in PCCP pipelines, including an upstream sensing light path, a downstream sensing light path, a bidirectional beam combiner, a sensing optical cable, a synchronous trigger module, a data acquisition module, a signal processing module and an alarm and control host.

[0006] The upper sensing optical path includes a laser B, an optical pulse modulation module B, an optical amplification module B, a circulator B and a detector B, and the lower sensing optical path includes a laser A, an optical amplification module A, an optical beam splitter, two circulators A, a coupler and a detector A.

[0007] The laser B is connected to the optical pulse modulation module B, the output of the optical pulse modulation module B corresponds to the optical amplifier module B, the optical amplifier module B is connected to the circulator B, the circulator B corresponds to the bidirectional beam combiner and the detector respectively, the bidirectional beam combiner is connected to the head end of the sensor optical cable, the output of the detector B is connected to the data acquisition module, the data acquisition module is connected to the signal processing module, the signal processing module corresponds to the alarm control host, the alarm control host is connected to the synchronous trigger module, and the output of the synchronous trigger module is connected to the laser B and the laser A respectively.

[0008] The output of the laser A is connected to the optical amplifier module A, the output of the optical amplifier module A is connected to the optical beam splitter, the two outputs of the optical beam splitter correspond to the circulator A respectively, the output port 1 of the circulator A corresponds to the end of the sensor optical cable, and the output port 2 is connected to the coupler.

[0009] The output port 1 of the circulator A is connected to the bidirectional combiner, the output port 2 is connected to the coupler, the output of the coupler is connected to the detector A, and the output end of the detector A is connected to the data acquisition module.

[0010] Further: the laser A and laser B are both narrow bandwidth, continuous light waves. The emission wavelengths of the laser A and laser B are different. After the laser B passes through the optical pulse modulation module, it is transmitted in the sensor optical cable as a pulse signal with a fixed repetition frequency.

[0011] Further: the detector A and the detector B are different wavelength models. The wavelength parameter of the detector A is consistent with that of the laser A. The wavelength parameter of the detector B is consistent with that of the laser B.

[0012] Furthermore: the light energy values ​​of the two output ports of the optical beam splitter are equal, that is, the ratio is 1:1.

[0013] Furthermore: the wavelength parameters of the bidirectional beam combiner are jointly determined by laser A and laser B, and the transmission direction is bidirectional and reversible.

[0014] Furthermore: the coupler is a 2×2 coupler.

[0015] Furthermore: the synchronization trigger module controls laser A and laser B to be in a synchronous working state.

[0016] Furthermore: the head and tail ends of the sensor optical cable correspond to the same position of the PCCP pipeline.

[0017] The utility model provides a distributed optical fiber sensing system for improving the detection of broken wires in PCCP pipelines. The working principle is as follows:

[0018] For the down sensing optical path, laser A emits a narrowband continuous light wave, which enters the optical beam splitter after amplification, and outputs two paths of light with equal power. One path passes through circulator A and bidirectional beam combiner to enter the head end of the sensing optical cable and propagates in a clockwise direction; the second path passes through circulator A, is incident from the end of the sensing optical cable, and is transmitted in a counterclockwise direction. Interference occurs at the coupler. If there is no broken wire event in the PCCP pipeline, the frequency information carried by the interference signal received by detector A at this time does not contain the characteristic part of the broken wire signal, especially the high-frequency characteristic signal; if there is a broken wire event, the sound wave generated by the broken wire signal will act on the sensing optical cable, and the frequency composition of the interference signal received by detector A contains the high-frequency characteristic signal of the broken wire signal. At the same time, the broken wire position point is located through the uploading optical path.

[0019] Compared with the prior art, the utility model has the following advantages and effects: the system determines whether a broken wire event occurs based on the rich high-frequency information detected by the down-sensing optical path, and when the characteristic information of the broken wire signal is included, the up-sensing optical path is used to quickly and accurately locate the broken wire event. The utility model reduces the pressure of the system to process data volume, solves the constraint relationship between the system monitoring distance and the detection frequency in the distributed optical fiber sensing, and at the same time improves the accuracy of the system PCCP broken wire detection and reduces the system positioning error. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a connection diagram of a distributed optical fiber sensing system for PCCP pipeline broken wire detection in a utility model;

[0021] Figure 2 A schematic diagram of a specific example of a sensing optical cable and a pipeline broken wire position of a distributed optical fiber sensing system for improving PCCP pipeline broken wire detection based on the utility model;

[0022] In the figure: 1. Lower sensing optical path; 2. Upper sensing optical path; 3. Laser A; 4. Optical amplifier module A; 5. Optical beam splitter; 6. Circulator A; 7. Coupler; 8. Detector A; 9. Circulator A; 10. Laser B; 11. Optical pulse modulation module B; 12. Optical amplifier module B; 13. Circulator B; 14. Detector B; 15. Bidirectional beam combiner; 16. Data acquisition module; 17. Signal processing module; 18. Alarm and control host; 19. Synchronous trigger module; 20. Sensing optical cable; 21. PCCP pipeline; 22. Sensing optical cable head end; 23. Sensing optical cable tail end; 24. Position of broken wire in PCCP. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0025] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features; in the description of the present utility model, unless otherwise specified, "plurality" means two or more.

[0026] Example 1

[0027] The present embodiment provides a distributed optical fiber sensing system for detecting broken wires in a PCCP pipeline, comprising an upstream optical sensing path 1, a downstream optical sensing path 2, a bidirectional beam combiner 15, a sensing optical cable 20, a synchronous trigger module 19, a data acquisition module 16, a signal processing module 17 and an alarm and control host 18.

[0028] The upper sensing optical path includes a laser B10, an optical pulse modulation module B11, an optical amplifier module B12, a circulator B13 and a detector B14, and the lower sensing optical path includes a laser A3, an optical amplifier module A4, an optical beam splitter 5, two circulators A6 and 9, a coupler 7 and a detector A8.

[0029] Laser B10 is connected to optical pulse modulation module B11, the output of optical pulse modulation module B11 corresponds to optical amplifier module B12, optical amplifier module B12 is connected to circulator B13, circulator B13 corresponds to bidirectional beam combiner 15 and detector 14 respectively, bidirectional beam combiner 15 corresponds to the head end of sensor optical cable 20, detector B14 output is connected to data acquisition module, data acquisition module 16 is connected to signal processing module 17, signal processing module 17 corresponds to alarm control host 18, alarm control host 18 is connected to synchronous trigger module 19, synchronous trigger module 19 output is connected to laser B10 and laser A3 respectively,

[0030] The output of laser A3 is connected to optical amplifier module A4, the output of optical amplifier module A4 is connected to optical beam splitter 5, the two outputs of optical beam splitter 5 correspond to circulators A6 and 9 respectively, the output port 1 of circulator A9 corresponds to the end of sensor optical cable 20, and the output port 2 is connected to coupler 7.

[0031] Output port 1 of circulator A6 is connected to bidirectional combiner 15 , output port 2 is connected to coupler 7 , output of coupler 7 is connected to detector A8 , and output end of detector A8 is connected to data acquisition module 16 .

[0032] The laser A3 and the laser B10 are both narrow bandwidth, continuous light waves. The emission wavelengths of the laser A3 and the laser B10 are different. After passing through the optical pulse modulation module 11, the laser B10 is transmitted in the sensor optical cable 20 as a pulse signal with a fixed repetition frequency.

[0033] The detector A8 and the detector B14 are different wavelength models. The wavelength parameters of the detector A8 are consistent with those of the laser A3. The wavelength parameters of the detector B14 are consistent with those of the laser B10.

[0034] The light energy values ​​of the two output ports of the optical beam splitter 5 are equal, that is, the ratio is 1:1.

[0035] The wavelength parameters of the bidirectional beam combiner 15 are jointly determined by the laser A3 and the laser B10, and the transmission direction is bidirectional and reversible.

[0036] The coupler 7 is a 2×2 coupler.

[0037] The synchronous trigger module 19 controls the laser A3 and the laser B10 to be in a synchronous working state.

[0038] The head and tail ends of the sensor optical cable 20 are located on one side of the PCCP pipeline, or on both sides of the pipeline.

[0039] The data acquisition module uses a high-speed acquisition card to synchronously receive the data transmitted by detector A8 and detector B14.

[0040] The signal processing module 17 analyzes and processes the data transmitted by the data acquisition module 16 to achieve accurate identification and positioning of the broken wire signal.

[0041] The alarm and control host 18 displays the position and time of the broken wire event identified by the signal processing module 17 in a visual manner. At the same time, the alarm and control host 18 can be used to set parameters for the synchronous trigger module 19, the optical amplifier module A4, and the optical amplifier module B12 respectively.

[0042] The utility model provides a distributed optical fiber sensing system for PCCP pipeline broken wire detection, and the determination of broken wire identification and positioning includes the following steps:

[0043] Step 1: Collect event information near the PCCP pipeline carried by the light wave when it is transmitted in the sensor optical cable. The specific operation method is as follows:

[0044] In the lower sensing optical path, the narrowband continuous light wave emitted by laser A enters the optical beam splitter after optical amplification, and outputs two transmission lights 1 and 2 with equal power;

[0045] After passing through circulator A and bidirectional combiner, transmission light 1 is connected to the head end of the sensor optical cable, and is transmitted to the tail end of the sensor optical cable in a clockwise direction, and is transmitted to the coupler through the output port 2 of circulator A;

[0046] The transmission light 2 enters the tail end of the sensor optical cable after passing through the circulator A, is transmitted to the head end of the sensor optical cable in a counterclockwise direction, and is transmitted to the coupler through the output port 2 of the circulator A;

[0047] Transmission light 1 and 2 interfere with each other at the coupler and are output to detector A. Detector A removes DC, filters, amplifies, and converts them into electrical signals. After high-speed acquisition and analog / digital conversion, they are transmitted to the signal processing module.

[0048] At the same time, in the uplink photosensitive path, the narrowband continuous light emitted by laser B passes through the optical pulse modulation module, enters the optical amplifier module as pulse light for amplification, passes through the ring 1 port and the bidirectional combiner, and is transmitted from the head end of the sensor optical cable to the tail end in a clockwise direction. Its backscattered light is connected to the detector B through the bidirectional combiner and the circulator 2 port, and is transmitted to the signal processing module after high-speed acquisition and analog / digital conversion.

[0049] Step 2: The system will analyze the signals collected in real time according to step 1 to determine whether there is a wire breakage event in the PCCP pipeline. The specific operations are as follows:

[0050] The signal processing module filters and de-noises the collected data, and obtains the frequency information distribution carried by the sensor optical cable through frequency domain transformation;

[0051] When the high-frequency characteristic frequency of the broken wire signal is not found in the carried frequency information, it means that there is no broken wire event in the PCCP pipeline. At this time, the signal processing module does not perform any analysis and processing on the data collected by the photosensitive path at this moment;

[0052] When the carried frequency information contains the characteristic frequency of the broken wire signal, especially the high-frequency characteristic signal, it means that a broken wire event has occurred in the PCCP pipeline. At the same time, the system signal processing module will analyze and calculate the data collected by the uploaded photosensitive path, obtain the location of the broken wire detected by the system, upload it to the alarm and control host to display the broken wire location and time in a visual way, and issue a corresponding alarm prompt;

[0053] Step 3: According to step 2, when a wire breakage event is detected in the PCCP pipeline, the location of the wire breakage event detected by the system is calculated;

[0054] The transmission speed of light waves in the sensor optical cable is:

[0055]

[0056] Where c is the speed of light waves in a vacuum and n is the refractive index of the optical fiber.

[0057] For the uploading optical sensing path, the relationship between the distance from the first end of the sensing optical fiber to a certain point on the link and time is:

[0058]

[0059] Assuming the length of the PCCP pipeline is L, the length of the laid sensor optical cable is 2L. When a wire breakage event occurs somewhere in the pipeline, the backscattered light will detect the event signal twice during the transmission process. Detector B detects the event signal at the corresponding time t1 and t2 respectively. The corresponding optical cable lengths are:

[0060]

[0061]

[0062] According to (3) and (4), the location where the wire breaks in the pipeline can be calculated as:

[0063]

[0064] Step 4: The broken wire position obtained by the signal processing module in step 3 is uploaded to the alarm and control host for visual display and alarm prompt.

[0065] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A distributed optical fiber sensing system for PCCP pipeline broken wire detection, characterized by: It comprises an upper sensing light path (1), a lower sensing light path (2), a bidirectional beam combiner (15), a sensing optical cable (20), a synchronous trigger module (19), a data acquisition module (16), a signal processing module (17) and an alarm and control host (18); The upper sensing optical path comprises a laser B (10), an optical pulse modulation module B (11), an optical amplification module B (12), a circulator B (13) and a detector B (14); the lower sensing optical path comprises a laser A (3), an optical amplification module A (4), an optical beam splitter (5), two circulators A, a coupler (7) and a detector A (8); The laser B (10) is connected to an optical pulse modulation module B (11), the output of the optical pulse modulation module B (11) is connected to an optical amplifier module B (12), the optical amplifier module B (12) is connected to a circulator B (13), the circulator B (13) is respectively connected to a bidirectional beam combiner (15) and a detector B (14), the output of the bidirectional beam combiner (15) is electrically connected to a sensor optical cable (20), the output of the detector B (14) is connected to a data acquisition module (16), the data acquisition module (16) is connected to a signal processing module (17), the signal processing module (17) is connected to an alarm control host (18), the alarm control host (18) is connected to a synchronous trigger module (19), and the output of the synchronous trigger module (19) is respectively connected to the laser B (10) and the laser A (3); The output of the laser A (3) is connected to the optical amplifier module A (4), the output of the optical amplifier module A (4) is connected to the optical beam splitter (5), the two outputs of the optical beam splitter (5) are respectively connected to two circulators A, one of the circulator A output ports 1 corresponds to the other end of the sensor optical cable (20), and port 2 is connected to the coupler (7); Another circulator A output port 1 is connected to a bidirectional combiner (15), and port 2 is connected to a coupler (7). The output of the coupler (7) is connected to a detector A (8), and the output end of the detector A (8) is connected to a data acquisition module (16).

2. A distributed optical fiber sensing system for detecting broken wires in PCCP pipelines according to claim 1, characterized in that: The laser A (3) and the laser B (10) are both narrow-bandwidth, continuous light waves; the emission wavelengths of the laser A (3) and the laser B (10) are different; after passing through an optical pulse modulation module B (11), the laser B (10) is transmitted in a sensing optical cable (20) as a pulse signal with a fixed repetition frequency.

3. A distributed optical fiber sensing system for detecting broken wires in PCCP pipelines according to claim 1, characterized in that: The detector A (8) and the detector B (14) are of different wavelength models; the wavelength parameter of the detector A (8) is consistent with that of the laser A (3); and the wavelength parameter of the detector B (14) is consistent with that of the laser B (10).

4. A distributed optical fiber sensing system for detecting broken wires in PCCP pipelines according to claim 1, characterized in that: The light energy values ​​of the two output ports of the optical beam splitter (5) are equal, that is, the ratio is 1:

1.

5. A distributed optical fiber sensing system for detecting broken wires in PCCP pipelines according to claim 1, characterized in that: The wavelength parameters of the bidirectional beam combiner (15) are jointly determined by the laser A (3) and the laser B (10), and the transmission direction is bidirectional and reversible.

6. A distributed optical fiber sensing system for detecting broken wires in PCCP pipelines according to claim 1, characterized in that: The coupler (7) is a 2×2 coupler.

7. A distributed optical fiber sensing system for detecting broken wires in PCCP pipelines according to claim 1, characterized in that: The synchronous trigger module (19) controls the laser A (3) and the laser B (10) to be in a synchronous working state.

8. A distributed optical fiber sensing system for detecting broken wires in PCCP pipelines according to claim 1, characterized in that: The head and tail ends of the sensor optical cable (20) correspond to the same position of the PCCP pipeline.

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