A city cable network status monitoring and early warning system and method based on distributed optical fiber multi-dimensional sensing

Abstract

The present application relates to a system and method for monitoring and warning the status of an urban cable network based on distributed optical fiber multi-dimensional sensing. The system includes an alternating multi-dimensional acoustic wave sensing optical cable and an acoustic wave detection system. The alternating multi-dimensional acoustic wave sensing optical cable is composed of scattering-enhanced optical fiber and single-mode optical fiber alternately connected, and is used to detect the sound information of abnormal discharge and foreign body intrusion behavior of the cable network; the acoustic wave detection system is connected to one end of the alternating multi-dimensional acoustic wave sensing optical cable, and transmits a detection optical signal to the optical cable and receives a reflected optical signal with sound information. The present application can take into account the requirements of long-distance monitoring and high signal-to-noise ratio and high detection frequency, and realize cable monitoring of optical fiber multi-dimensional sensing.

Description

Technical Field

[0001] The present application relates to the field of urban cable network status monitoring and early warning, and in particular to an urban cable network status monitoring and early warning system and method based on distributed optical fiber multi-dimensional sensing. Background Art

[0002] Cables play an especially important role in many fields such as power transportation, urban infrastructure and industrial production, and are essential infrastructure for people's daily lives. Cables in my country are extremely densely distributed. As the operating time increases, various problems will occur due to cable aging, which need to be discovered and repaired in a timely manner, otherwise it is easy to cause safety accidents and economic losses.

[0003] In response to the needs of long-distance, large-range, and real-time cable monitoring, distributed fiber optic sensing technology stands out from many pipeline monitoring technologies due to its high sensitivity, continuous large range, and strong anti-interference ability. It can conduct comprehensive and real-time monitoring of cables to ensure pipeline safety.

[0004] However, there is still a restrictive relationship between detection distance and detection accuracy, and between detection distance and detection frequency. Specifically, in distributed optical fiber sensing technology, due to the influence of optical fiber loss, its long-distance detection quality is poor, and the signal-to-noise ratio of the detection result is low, which cannot meet the needs of abnormal discharge that requires high-performance detection; due to the high frequency of abnormal discharge signals, a higher detection frequency is required, but the detection frequency of distributed acoustic wave sensing technology is also limited by the detection distance.

[0005] In summary, although distributed fiber optic sensing technology can better meet the needs of cable network monitoring, there is still a restrictive relationship between detection distance and detection accuracy, and between detection distance and detection frequency. In practical applications, a detection method that can break this bottleneck is needed. Summary of the invention

[0006] The purpose of the embodiments of the present application is to provide a system and method for monitoring and early warning the status of an urban cable network based on distributed optical fiber multi-dimensional sensing, which reallocates the limited time and energy resources of distributed optical fiber sensing and achieves simultaneous high-quality identification of multi-dimensional abnormal events in the cable.

[0007] To achieve the above objectives, this application provides the following technical solutions:

[0008] In a first aspect, an embodiment of the present application provides a city cable network status monitoring and early warning system based on distributed optical fiber multi-dimensional sensing, including an alternating multi-dimensional acoustic wave sensing optical cable and an acoustic wave detection system.

[0009] The alternating multi-dimensional acoustic wave sensing optical cable is composed of scattering-enhanced optical fibers and single-mode optical fibers connected alternately, and is used to detect the sound information of abnormal discharge and foreign body intrusion in the cable network;

[0010] The acoustic wave detection system is connected to one end of the alternating multi-dimensional acoustic wave sensing optical cable, transmits a detection optical signal to the optical cable and receives a reflected optical signal carrying acoustic information.

[0011] The scattering-enhanced optical fiber is densely wound around the cable joint to enhance the scattering intensity of the detection light, and can achieve high-precision, high-sampling rate ultrasonic abnormal discharge detection in conjunction with a multi-dimensional acoustic wave demodulation algorithm; the single-mode optical fiber is directly laid along the cable to detect acoustic wave information of foreign object intrusion along the line.

[0012] The dense winding methods of scattering enhanced optical fiber include spiral winding and S-shaped reel-and-sticking. The spiral winding method is to spirally wind the optical fiber in the key test area, and then wrap it tightly with sticky material; the S-shaped reel-and-sticking method is to attach the optical fiber to the sticky material in an S-shape, and then wrap the sticky material tightly and lay it on the cable joint.

[0013] The acoustic wave detection system includes an optical transmitting module, an optical receiving module, a signal demodulation module, and a cable network status early warning module. The optical transmitting module sends an optical signal to a sensing optical fiber connected to an alternating multi-dimensional acoustic wave sensing optical cable. The optical receiving module receives the optical signal reflected by the alternating multi-dimensional acoustic wave sensing optical cable on the sensing optical fiber and transmits it to the signal demodulation module. The signal demodulation module demodulates the optical signal received by the optical receiving module and transmits the obtained information to the cable network status early warning module for early warning.

[0014] In a second aspect, an embodiment of the present application provides a method for monitoring and early warning of urban cable network status based on distributed optical fiber multi-dimensional sensing, comprising the following steps:

[0015] Multi-dimensional acoustic wave demodulation: Utilize the reflected light signal with sound information received by the acoustic wave detection system, and simultaneously demodulate the high-frequency abnormal discharge and low-frequency foreign body intrusion acoustic wave information;

[0016] Grid status warning: Use high-frequency abnormal discharge and low-frequency foreign object intrusion sound wave information to provide grid status warning.

[0017] The multi-dimensional sound wave demodulation specifically includes:

[0018] A1: Send positioning pulses, determine the position of the scattering-enhanced optical fiber through the back-reflected optical signal according to the characteristics of the scattering-enhanced optical fiber, and locate the abnormal discharge monitoring position at the cable joint, where the position of the i-th cable joint is L i ;

[0019] A2: Determine the cable connector position L in high sampling rate mode and low sampling rate mode according to the abnormal discharge monitoring position. i Equivalent arrival time t of reflected signal i Relationship with sampling rate;

[0020] A3: Select the appropriate high sampling rate mode sampling rate f H and low sampling rate mode sampling rate f L ;

[0021] A4: Alternately perform high sampling rate mode sampling and low sampling rate mode sampling according to a specific period to collect sound wave signals;

[0022] A5: Different locations are distinguished by the equivalent arrival time of the reflected light signal, and the high-frequency abnormal discharge and low-frequency foreign body intrusion sound wave information at different locations are demodulated by phase demodulation of the reflected light signal.

[0023] Cable connector position L i Equivalent arrival time t of reflected signal i It is expressed as:

[0024]

[0025] Where n is the fiber refractive index, c is the speed of light, and f is the sampling rate.

[0026] Wherein, in low sampling rate mode, N=0, and in high sampling rate mode, N is an integer greater than or equal to zero, such that

[0027] Low sampling rate mode sampling rate f L Need to meet L is the length of the sensing optical fiber;

[0028] High sampling rate mode sampling rate f H The minimum value that satisfies the following two conditions:

[0029] B1: greater than 3 times the typical frequency of abnormal discharge signals, that is:

[0030] f H >3f e

[0031] B2: All cable connector positions L i Equivalent arrival time t of reflected signal i There is no time overlap, that is, any two cable joints must satisfy:

[0032] |t n -t m |>τ+n(L n +L m ) / 2c

[0033] Where τ is the pulse width, L n With L m is the length of the nth and mth cable joints.

[0034] The ratio of alternating high sampling rate mode sampling and low sampling rate mode sampling in a specific period is 1:20~1:40, the high sampling rate mode samples every 0.5s, and the low sampling rate mode samples every 10~20s.

[0035] Among them, the high sampling rate mode only collects the scattering enhanced optical fiber signal at the cable joint, and the low sampling rate mode collects the single-mode optical fiber signal.

[0036] The power grid status warning uses time-frequency information to judge abnormal power grid discharge and foreign object intrusion events, and realizes power grid status warning through AI neural network.

[0037] Compared with the prior art, the beneficial effects of the present invention are: it can take into account the requirements of long-distance monitoring and high signal-to-noise ratio and high detection frequency, and realize cable monitoring of optical fiber multi-dimensional sensing. Fiber coding is implemented for the abnormal discharge detection unit, and abnormal discharge signals with high signal-to-noise ratio and high detection frequency are located and distinguished through coding, while improving the detection signal-to-noise ratio of its sensing channel, so as to realize highly sensitive abnormal discharge detection; at the same time, since there is no high signal-to-noise ratio and high detection frequency requirement for third-party intrusion signals, ordinary optical fiber is used for detection, which can provide time and energy resources for the detection of abnormal discharge signals. Through the system design of this patent, the limited time and energy resources of distributed optical fiber sensing are reallocated, and simultaneous high-quality identification of multi-dimensional abnormal events in cables is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 This is a schematic diagram of the layout of the optical fiber sensor in the cable;

[0040] Figure 2 This is the structural connection diagram of the urban cable network status monitoring and early warning system based on distributed optical fiber multi-dimensional sensing;

[0041] Figure 3 It is a specific implementation flow chart of the urban cable network status monitoring and early warning system based on distributed optical fiber multi-dimensional sensing. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0043] The terms "comprises," "comprising," or any other variation thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0044] The terms "first", "second", etc. are only used to distinguish one entity or operation from another entity or operation, and should not be understood as indicating or implying relative importance, nor should they be understood as requiring or implying any such actual relationship or order between these entities or operations.

[0045] like Figure 1 and Figure 2 As shown, a city cable network status monitoring and early warning system based on distributed optical fiber multi-dimensional sensing includes an alternating multi-dimensional acoustic wave sensing optical cable and an acoustic wave detection system.

[0046] The alternating multi-dimensional acoustic wave sensing optical cable is composed of scattering-enhanced optical fibers and single-mode optical fibers connected alternately, and is used to detect the sound information of abnormal discharge and foreign body intrusion in the cable network;

[0047] The acoustic wave detection system is connected to one end of the alternating multi-dimensional acoustic wave sensing optical cable, transmits a detection optical signal to the optical cable and receives a reflected optical signal carrying acoustic information.

[0048] The scattering-enhanced optical fiber is densely wound around the cable joint to enhance the scattering intensity of the detection light, and can achieve high-precision, high-sampling rate ultrasonic abnormal discharge detection in conjunction with a multi-dimensional acoustic wave demodulation algorithm; the single-mode optical fiber is directly laid along the cable to detect acoustic wave information of foreign object intrusion along the line.

[0049] The dense winding methods of scattering enhanced optical fiber include spiral winding and S-shaped reel-and-sticking. The spiral winding method is to spirally wind the optical fiber in the key test area, and then wrap it tightly with sticky material; the S-shaped reel-and-sticking method is to attach the optical fiber to the sticky material in an S-shape, and then wrap the sticky material tightly and lay it on the cable joint.

[0050] The acoustic wave detection system includes an optical transmitting module, an optical receiving module, a signal demodulation module, and a cable network status early warning module. The optical transmitting module sends an optical signal to a sensing optical fiber connected to an alternating multi-dimensional acoustic wave sensing optical cable. The optical receiving module receives the optical signal reflected by the alternating multi-dimensional acoustic wave sensing optical cable on the sensing optical fiber and transmits it to the signal demodulation module. The signal demodulation module demodulates the optical signal received by the optical receiving module and transmits the obtained information to the cable network status early warning module for early warning.

[0051] The specific implementation process is as follows Figure 3 As shown, specifically,

[0052] 1. Sensor optical cable Figure 1 As shown in the layout, the cable joint adopts the layout method of the above system;

[0053] 2. Emit positioning pulses, determine the position of the scattering-enhanced optical fiber through the back-reflected optical signal according to the characteristics of the scattering-enhanced optical fiber, and locate the abnormal discharge monitoring position at the cable joint, where the position of the i-th cable joint is L i ;

[0054] 3. Determine the relationship based on the abnormal discharge monitoring position and determine the cable connector position L in high sampling rate mode and low sampling rate mode. i Equivalent arrival time t of reflected signal i Relationship with sampling rate, selection of appropriate high sampling rate mode sampling rate f H and low sampling rate mode sampling rate f L

[0055] 4. Alternate between high sampling rate mode and low sampling rate mode sampling in a specific cycle to collect sound wave signals. The ratio of high sampling rate mode and low sampling rate mode sampling in a specific cycle is 1:20 to 1:40. The high sampling rate mode samples 0.5 seconds each, and the low sampling rate mode samples 10 to 20 seconds.

[0056] 5. Different positions are distinguished by the equivalent arrival time of the reflected light signal, and the high-frequency abnormal discharge and low-frequency foreign body intrusion sound wave information at different positions are demodulated by phase demodulation of the reflected light signal.

[0057] Through the system design of this patent, the limited time and energy resources of distributed optical fiber sensing are reallocated, achieving simultaneous high-quality identification of multi-dimensional abnormal events in the cable.

[0058] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A city cable network status monitoring and early warning system based on distributed optical fiber multi-dimensional sensing, characterized in that: Including alternating multi-dimensional acoustic wave sensing optical cable and acoustic wave detection system, The alternating multi-dimensional acoustic wave sensing optical cable is composed of scattering-enhanced optical fibers and single-mode optical fibers connected alternately, and is used to detect the sound information of abnormal discharge and foreign body intrusion in the cable network; The acoustic wave detection system is connected to one end of the alternating multi-dimensional acoustic wave sensing optical cable, transmits a detection optical signal to the optical cable and receives a reflected optical signal carrying acoustic information.

2. According to claim 1, a city cable network status monitoring and early warning system based on distributed optical fiber multi-dimensional sensing is characterized in that: The scattering-enhanced optical fiber is densely wound around the cable joint to enhance the scattering intensity of the detection light, and can achieve high-precision, high-sampling rate ultrasonic abnormal discharge detection in conjunction with a multi-dimensional acoustic wave demodulation algorithm; the single-mode optical fiber is directly laid along the cable to detect acoustic wave information of foreign object intrusion along the line.

3. The urban cable network status monitoring and early warning system based on distributed optical fiber multi-dimensional sensing according to claim 2 is characterized in that: The dense winding methods of scattering enhanced optical fiber include spiral winding and S-shaped reel-and-sticking. The spiral winding method is to spirally wind the optical fiber in the key test area, and then wrap it tightly with sticky material; the S-shaped reel-and-sticking method is to attach the optical fiber to the sticky material in an S-shape, and then wrap the sticky material tightly and lay it on the cable joint.

4. According to claim 1, a city cable network status monitoring and early warning system based on distributed optical fiber multi-dimensional sensing is characterized in that: The acoustic wave detection system includes an optical transmitting module, an optical receiving module, a signal demodulation module, and a cable network status early warning module. The optical transmitting module sends an optical signal to a sensing optical fiber connected to an alternating multi-dimensional acoustic wave sensing optical cable. The optical receiving module receives the optical signal reflected by the alternating multi-dimensional acoustic wave sensing optical cable on the sensing optical fiber and transmits it to the signal demodulation module. The signal demodulation module demodulates the optical signal received by the optical receiving module and transmits the obtained information to the cable network status early warning module for early warning.

5. A method for monitoring and early warning of urban cable network status based on distributed optical fiber multi-dimensional sensing, characterized in that: The following steps are involved: Multi-dimensional acoustic wave demodulation: Utilize the reflected light signal with sound information received by the acoustic wave detection system, and simultaneously demodulate the high-frequency abnormal discharge and low-frequency foreign body intrusion acoustic wave information; Grid status warning: Use high-frequency abnormal discharge and low-frequency foreign object intrusion sound wave information to provide grid status warning.

6. The method for monitoring and early warning of urban cable network status based on distributed optical fiber multi-dimensional sensing according to claim 5 is characterized in that: The multi-dimensional sound wave demodulation specifically includes: A1: Send positioning pulses, determine the position of the scattering-enhanced optical fiber through the back-reflected optical signal according to the characteristics of the scattering-enhanced optical fiber, and locate the abnormal discharge monitoring position at the cable joint, where the position of the i-th cable joint is L i ; A2: Determine the cable connector position L in high sampling rate mode and low sampling rate mode according to the abnormal discharge monitoring position. i Equivalent arrival time t of reflected signal i Relationship with sampling rate; A3: Select the appropriate high sampling rate mode sampling rate f H and low sampling rate mode sampling rate f L ; A4: Alternately perform high sampling rate mode sampling and low sampling rate mode sampling according to a specific period to collect sound wave signals; A5: Different locations are distinguished by the equivalent arrival time of the reflected light signal, and the high-frequency abnormal discharge and low-frequency foreign body intrusion sound wave information at different locations are demodulated by phase demodulation of the reflected light signal.

7. The method for monitoring and early warning of urban cable network status based on distributed optical fiber multi-dimensional sensing according to claim 6 is characterized in that: Cable connector position L i Equivalent arrival time t of reflected signal i It is expressed as: Where n is the fiber refractive index, c is the speed of light, and f is the sampling rate. Wherein, in low sampling rate mode, N=0, and in high sampling rate mode, N is an integer greater than or equal to zero, such that 8. The method for monitoring and early warning of urban cable network status based on distributed optical fiber multi-dimensional sensing according to claim 7 is characterized in that: Low sampling rate mode sampling rate f L Need to meet L is the length of the sensing optical fiber; High sampling rate mode sampling rate f H The minimum value that satisfies the following two conditions: B1: greater than 3 times the typical frequency of abnormal discharge signals, that is: in H >3f e B2: All cable connector positions L i Equivalent arrival time t of reflected signal i There is no time overlap, that is, any two cable joints must satisfy: |t n -t m |>τ+n(L n +L m ) / 2c Where τ is the pulse width, L n With L m is the length of the nth and mth cable joints.

9. The method for monitoring and early warning of urban cable network status based on distributed optical fiber multi-dimensional sensing according to claim 7 is characterized in that: The ratio of alternating high sampling rate mode sampling and low sampling rate mode sampling in a specific period is 1:20~1:40, the high sampling rate mode samples every 0.5s, and the low sampling rate mode samples every 10~20s. Among them, the high sampling rate mode only collects the scattering enhanced optical fiber signal at the cable joint, and the low sampling rate mode collects the single-mode optical fiber signal.

10. The method for monitoring and early warning of urban cable network status based on distributed optical fiber multi-dimensional sensing according to claim 5, characterized in that: The power grid status warning uses time-frequency information to judge abnormal power grid discharge and foreign object intrusion events, and realizes power grid status warning through AI neural network.

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