Power pipe network comprehensive monitoring system and monitoring method based on passive sensing

Abstract

The invention provides a power pipe network comprehensive monitoring system and monitoring method based on passive sensing, and belongs to the technical field of power pipe network monitoring. The monitoring method comprises the following steps of: injecting high-power and low-power periodic pulse optical signals into the same monitoring optical fiber at the same time; acquiring a Rayleigh scattering signal and a Raman scattering signal returned by the monitoring optical fiber; the Raman scattering signal comprises a Stokes Raman scattering signal and an anti-Stokes Raman scattering signal; acquiring a vibration source position and a vibration source type in the power pipe network by using the Rayleigh scattering signal; and acquiring internal temperature data of the power pipe network by using the Raman scattering signal. According to the invention, distributed temperature and vibration information of the power cable can be effectively provided in real time, cable faults can be accurately and timely eliminated, and safe operation of the cable can be effectively ensured. According to the invention, the wavelength division multiplexing technology and the pulse modulation technology are adopted to provide time-division high-power and low-power pulse sequences, so that multi-point distributed optical fiber vibration and temperature measurement is realized on the same monitoring optical fiber.

Description

Technical Field

[0001] The present invention belongs to the technical field of power pipe network monitoring, and in particular relates to a comprehensive monitoring system and a monitoring method for a power pipe network based on passive sensing. Background Art

[0002] The cables (electric cables, optical cables) for power networks are numerous, complex in structure, diverse in laying methods, and subject to changeable external factors, making the management of cable lines not as clear and definite as that of high-voltage transmission lines. During on-site operation and maintenance, any changes in the cable body, cable laying and installation conditions, cable operating conditions, and other external factors will cause environmental changes in the power network, and will inevitably pose a threat to the safe operation of the cables, especially temperature rise is one of the main factors causing cable failures.

[0003] However, due to the limitations of the cable body, the network environment and the length of the network path, it is difficult for operation and maintenance personnel to be familiar with the environment of each cable path, and it is also difficult to inspect the internal environment of the network at a high frequency, so it is difficult to grasp the actual operation status of the power network. Therefore, a method that can conduct real-time comprehensive monitoring of the power network is needed. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a comprehensive monitoring system and a monitoring method for a power pipe network based on passive sensing in view of the deficiencies in the prior art.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A passive sensing-based integrated monitoring system for electric power pipe networks, comprising a monitoring optical fiber arranged in the same pipe corridor as the electric power pipe network to be monitored, a laser, an acousto-optic demodulator, a circulator and a wavelength division multiplexer connected in sequence according to the direction of laser transmission, and a photoelectric detector, a data acquisition card and a host computer electrically connected in sequence; the laser is used to generate a continuous coherent light source; the acousto-optic modulator is used to modulate the light source into a high-power or low-power periodic pulse light signal; the pulse light signal is coupled to the wavelength division multiplexer through the circulator and then injected into the monitoring optical fiber; the wavelength division multiplexer is also used to receive the The optical signal transmitted back by the monitoring optical fiber; the wavelength division multiplexer extracts Stokes Raman scattering and anti-Stokes Raman scattering from the returned optical signal and transmits them to different photoelectric detectors respectively; the wavelength division multiplexer extracts Rayleigh scattering from the returned optical signal and transmits it to the circulator, which is coupled to another photoelectric detector by the circulator; the photoelectric detector is used to convert the optical signal into an electrical signal; the data acquisition card is electrically connected to the three photoelectric detectors, and is used to collect the electrical signals corresponding to Stokes Raman scattering, anti-Stokes Raman scattering and Rayleigh scattering respectively and transmit them to the host computer.

[0006] Furthermore, an amplifier and a fiber Bragg grating are connected in series between the acousto-optic demodulator and the circulator; the amplifier is used to amplify the pulse light signal modulated by the acousto-optic demodulator; and the fiber Bragg grating is used to filter out the spontaneous radiation noise in the amplified pulse light signal.

[0007] Furthermore, the wavelength division multiplexer is provided with two filter ports having a certain wavelength bandwidth and used for respectively extracting Stokes Raman scattering and anti-Stokes Raman scattering; the filter ports are optically connected to the photodetector one by one.

[0008] A comprehensive monitoring method for electric power pipe network based on passive sensing is implemented based on the monitoring system, comprising: injecting high and low power periodic pulse light signals into the same monitoring optical fiber at the same time; obtaining Rayleigh scattering signals and Raman scattering signals returned by the monitoring optical fiber; the Raman scattering signals include Stokes Raman scattering signals and anti-Stokes Raman scattering signals; obtaining the position and type of vibration sources inside the electric power pipe network by using the Rayleigh scattering signals; and obtaining temperature data inside the electric power pipe network by using the Raman scattering signals.

[0009] Furthermore, the method of using Rayleigh scattering signals to obtain the location and type of vibration sources inside the power pipeline network includes: obtaining a Rayleigh scattering curve from the Rayleigh scattering signal; processing the Rayleigh scattering curve using a moving average method to obtain a moving average curve; processing the moving average curve using a moving difference method to obtain a moving difference curve; obtaining the location of the vibration source by superimposing the moving difference curves; obtaining an intensity curve that reflects the intensity change of the vibration position point according to the moving difference curve; performing Fourier transform on the intensity curve to obtain the vibration frequency of the vibration source; and identifying the type of the vibration source according to the vibration frequency and location of the vibration source.

[0010] Furthermore, the moving average curve is expressed as , , , , where N is the number of Rayleigh scattering curves, M is the number of moving averages, represents the kth Rayleigh scattering curve.

[0011] Furthermore, the moving difference curve is expressed as , where S is the interval of moving difference.

[0012] Furthermore, the method for obtaining the internal temperature data of the power pipe network using the Raman scattering signal includes: performing noise reduction processing on the Raman scattering signal using a digital cumulative averaging method; and obtaining the internal temperature data of the power pipe network using the Raman scattering signal after noise reduction.

[0013] Furthermore, the method of performing noise reduction processing on the Raman scattering signal by using the digital cumulative averaging method includes: performing linear superposition on the Raman scattering signal for multiple times and then calculating the root mean square value.

[0014] Furthermore, the number of linear superpositions is 10,000-20,000.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention only needs to use the fiber core in the communication optical cable laid in the same pipe corridor as the communication medium, without laying or using special sensor optical fiber separately; no other sensors need to be added to the outside of the monitoring system, and there is no need to actively power the sensor, which reduces the management and maintenance costs in the later stage. The monitoring system and monitoring method of the present invention can timely identify the location of the vibration source and the possible vibration type, and do not process harmless vibrations such as wind, rain, thunder, and normal vehicle driving; for harmful vibration sources such as manual excavation and mechanical construction, the present invention can immediately issue an alarm after identification, which is convenient for the staff to take measures in time according to the location of the vibration source; the monitoring system and monitoring method of the present invention can timely identify the abnormal temperature inside the power pipeline network, which is convenient for the staff to take measures in time to ensure the safe operation of the cable. The present invention can effectively and real-time provide distributed temperature and vibration information of the power cable, accurately and timely eliminate cable faults, effectively ensure the safe operation of the cable, and improve the level of refinement of operation and maintenance management, which can reduce the accident rate and reduce the economic losses of accidents. The present invention can realize online monitoring of the cable body, pipeline environment and pipeline security, comprehensively monitor the operation of the power cable, and provide a reliable basis for cable monitoring and management.

[0016] The present invention uses Rayleigh scattering signals to realize distributed vibration sensing, and uses Raman scattering signals to realize distributed temperature sensing. However, vibration detection and temperature detection have different requirements for light sources. When vibration detection is performed, the line width of the light source is required to be narrow, while when temperature detection is performed, the light source power needs to be sufficiently high. In view of the above situation, the present invention uses wavelength division multiplexing technology and pulse modulation technology to provide the system with time-divided high and low power pulse sequences to obtain high signal-to-noise ratio spontaneous scattering signals to demodulate vibration and temperature, thereby realizing multi-point distributed optical fiber vibration and temperature measurement on the same monitoring optical fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0018] Figure 1 : A schematic diagram of the monitoring system of the present invention; Figure 2 : Flow chart of the monitoring method of the present invention. DETAILED DESCRIPTION

[0019] In order to better understand the present invention, the content of the present invention is further clearly described below in conjunction with the embodiments and the accompanying drawings, but the protection content of the present invention is not limited to the following embodiments. In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details.

[0020] Embodiment 1: The purpose of this embodiment is to provide a comprehensive monitoring system for power pipeline network based on passive sensing.

[0021] like Figure 1 As shown, the monitoring system uses a laser to generate a continuous coherent light source, which is modulated by an acousto-optic modulator to generate high and low power periodic pulsed light signals. The pulsed light signal is amplified by an amplifier, and a fiber grating is used as a filter to filter out the spontaneous radiation noise generated after the light amplification. The amplified pulsed light signal is coupled to the wavelength division multiplexer through a circulator and then injected into the monitoring optical fiber. After the Rayleigh scattering, Stokes Raman scattering and anti-Stokes Raman scattering generated by the pulsed light are transmitted back to the wavelength division multiplexer along the monitoring light, the two filter ports of the wavelength division multiplexer with a certain wavelength bandwidth extract the Stokes Raman scattering and anti-Stokes Raman scattering in the scattered light respectively, and detect them respectively through photodetectors; the Rayleigh scattering extracted by the wavelength division multiplexer is coupled to another photodetector through a circulator for detection. The electrical signal converted by the photodetector is collected by the data acquisition card and transmitted to the host computer for processing and analysis.

[0022] The monitoring optical fiber is laid along the same pipe corridor as the power pipe network to be monitored, and the core of the communication optical cable in the same pipe corridor can be directly used as the monitoring optical fiber; the central wavelength of the laser is 1549.4nm; the acousto-optic modulator is used to modulate the optical signal using sound waves; the circulator is used to distribute and couple the optical signal; the fiber grating is used to selectively pass or block the optical signal of a specific wavelength; the wavelengths of the two filter ports of the wavelength division multiplexer are 1450nm and 1663nm respectively.

[0023] The light source generated by the laser is modulated by the acousto-optic modulator to generate high and low power pulse light signals. The Rayleigh scattering curve generated by the low power pulse light signal is more conducive to vibration measurement, while the Stokes scattering curve generated by the high power pulse has a better signal-to-noise ratio and is more conducive to temperature measurement.

[0024] See also Figure 2 The purpose of this embodiment is to provide a comprehensive monitoring method for power pipeline network based on passive sensing, which is applied to the monitoring system described in Example 1.

[0025] S1. Inject high and low power periodic pulse light signals into the monitoring optical fiber.

[0026] By utilizing the monitoring system, high-power and low-power periodic pulse optical signals are simultaneously injected into the same monitoring optical fiber.

[0027] S2. Acquire the Rayleigh scattering signal, Stokes Raman scattering signal and anti-Stokes Raman scattering signal returned by the monitoring optical fiber.

[0028] The monitoring system is used to obtain the Rayleigh scattering signal, Stokes Raman scattering signal and anti-Stokes Raman scattering signal returned by the monitoring optical fiber, and these signals are transmitted to the host computer and the subsequent steps are executed.

[0029] S3. Use Rayleigh scattering signals to obtain the location and type of vibration sources inside the power pipeline network.

[0030] This step uses the moving average and moving difference methods to process the Rayleigh scattering signal and identify the location and type of the vibration source.

[0031] In this step, a moving average process is first performed on the Rayleigh scattering curve collected from the Rayleigh scattering signal to obtain a moving average curve; then a moving difference process is performed on the moving average curve to obtain a moving difference curve.

[0032] If N Rayleigh scattering curves are collected from the Rayleigh scattering signal, the moving average curve after moving average can be expressed as , where M is the number of moving averages, , , The number of moving average curves is N-M+1.

[0033] Since two adjacent moving average curves are very similar, it is difficult to highlight the influence of vibration if the difference between adjacent curves is used for demodulation, so it is necessary to increase the interval of moving difference. Assuming the interval of moving difference is S, the moving difference curve can be expressed as The number of moving difference curves is N-M+1-S. Preferably, 3≤S≤9.

[0034] In this step, the moving average method can improve the signal-to-noise ratio while maintaining a high vibration frequency response range, while the moving difference method can highlight the difference between the front and back curves caused by vibration. The location of the vibration source can then be determined by superimposing the moving difference curves.

[0035] If the vibration source position is x, represents the intensity value corresponding to the position x of the ith moving difference curve. Then a new curve can be obtained, which is expressed as This intensity curve is a time domain diagram of the intensity change of the vibration position point obtained by sampling frequency N and sampling points N-M+1-S. The vibration frequency of the vibration source can be obtained by Fourier transformation. Finally, the possible type of vibration source can be identified by using the vibration frequency and vibration source location.

[0036] S4. Use Stokes Raman scattering signals and anti-Stokes Raman scattering signals to obtain the internal temperature data of the power pipeline network.

[0037] In this step, the digital cumulative averaging method is used to perform noise reduction processing on the Raman scattering signal and identify the temperature information of the measurement point.

[0038] Since the Raman scattering signal is very weak, especially the anti-Stokes Raman scattering signal which is sensitive to temperature, it is easily interfered by noise, making it difficult to obtain effective temperature information. These noises come from the noise generated by the unevenness of the medium during the transmission of scattered light and the random noise caused by the photoelectric conversion process in the system. Since their waveforms, amplitudes and phases are all random, this step first uses a digital cumulative average algorithm to remove the random noise generated in the system. The Raman scattering signal is a deterministic signal, which remains the signal after multiple average processing, so the signal-to-noise ratio can be improved, and effective temperature information can be easily extracted.

[0039] For the digital cumulative average algorithm of the Raman scattering signal, the signal can be linearly superimposed n times and then the root mean square value can be calculated. Preferably, 10000≤n≤20000.

[0040] The method of identifying temperature data from Raman scattering signals is a prior art and will not be described in detail here.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A passive sensing-based integrated monitoring system for electric power pipe networks, comprising a monitoring optical fiber arranged in the same pipe gallery as the electric power pipe network to be monitored, characterized in that: It also includes a laser, an acousto-optic demodulator, a circulator and a wavelength division multiplexer connected in sequence according to the laser transmission direction, and also includes a photoelectric detector, a data acquisition card and a host computer electrically connected in sequence; The laser is used to generate a continuous coherent light source; the acousto-optic modulator is used to modulate the light source into a high-power or low-power periodic pulse light signal; The pulse optical signal is coupled to the wavelength division multiplexer through the circulator and then injected into the monitoring optical fiber; The wavelength division multiplexer is also used to receive the optical signal returned by the monitoring optical fiber; the wavelength division multiplexer extracts Stokes Raman scattering and anti-Stokes Raman scattering from the returned optical signal and transmits them to different photodetectors respectively, and the wavelength division multiplexer extracts Rayleigh scattering from the returned optical signal and transmits it to the circulator, which is coupled to another photodetector by the circulator; The photoelectric detector is used to convert the optical signal into an electrical signal; the data acquisition card is electrically connected to the three photoelectric detectors, and is used to collect the electrical signals corresponding to Stokes Raman scattering, anti-Stokes Raman scattering and Rayleigh scattering, and transmit them to the host computer.

2. The passive sensing-based integrated monitoring system for electric power pipe networks according to claim 1 is characterized in that: An amplifier and a fiber Bragg grating are also connected in series between the acousto-optic demodulator and the circulator; The amplifier is used to amplify the pulse light signal modulated by the acousto-optic demodulator; The fiber grating is used to filter out the spontaneous radiation noise in the amplified pulse light signal.

3. The passive sensing-based integrated monitoring system for electric power pipe networks according to claim 1 is characterized in that: The wavelength division multiplexer is provided with two filter ports with a certain wavelength bandwidth and used for respectively extracting Stokes Raman scattering and anti-Stokes Raman scattering; the filter ports are optically connected to the photoelectric detectors one by one.

4. A comprehensive monitoring method for a power network based on passive sensing, implemented based on the monitoring system according to any one of claims 1 to 3, characterized in that: include: High and low power periodic pulse optical signals are injected into the same monitoring optical fiber simultaneously; Acquire the Rayleigh scattering signal and Raman scattering signal returned by the monitoring optical fiber; The Raman scattering signal includes a Stokes Raman scattering signal and an anti-Stokes Raman scattering signal; Use Rayleigh scattering signals to obtain the location and type of vibration sources inside the power pipeline network; The Raman scattering signal is used to obtain the internal temperature data of the power pipeline network.

5. The method for comprehensive monitoring of electric power pipe network based on passive sensing according to claim 4 is characterized in that: Methods for obtaining the location and type of vibration sources inside the power pipeline network using Rayleigh scattering signals include: Obtaining Rayleigh scattering curve from Rayleigh scattering signal; The Rayleigh scattering curve is processed by using the moving average method to obtain a moving average curve; The moving average curve is processed by the moving difference method to obtain the moving difference curve; The location of the vibration source is obtained by superimposing the moving difference curves; An intensity curve reflecting the intensity change of the vibration position point is obtained according to the moving difference curve; Perform Fourier transformation on the intensity curve to obtain the vibration frequency of the vibration source; The type of the vibration source is identified according to the vibration frequency and location of the vibration source.

6. The method for comprehensive monitoring of electric power pipe network based on passive sensing according to claim 5 is characterized in that: The moving average curve is expressed as , , , , where N is the number of Rayleigh scattering curves, M is the number of moving averages, represents the kth Rayleigh scattering curve.

7. The method for comprehensive monitoring of electric power pipe network based on passive sensing according to claim 6 is characterized in that: The moving difference curve is expressed as , where S is the interval of moving difference.

8. The method for comprehensive monitoring of electric power pipe network based on passive sensing according to claim 4 is characterized in that: The method of obtaining the internal temperature data of the power pipe network by using Raman scattering signals includes: The Raman scattering signal is de-noised using the digital cumulative averaging method; The internal temperature data of the power pipeline network is obtained using the noise-reduced Raman scattering signal.

9. The method for comprehensive monitoring of electric power pipe network based on passive sensing according to claim 8 is characterized in that: The method for performing noise reduction processing on Raman scattering signals by using digital cumulative averaging method comprises: performing linear superposition on the Raman scattering signals for multiple times and then calculating the root mean square value.

10. The method for comprehensive monitoring of electric power pipe network based on passive sensing according to claim 9 is characterized in that: The number of linear superpositions is 10,000-20,000.

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