Rayleigh-Raman fusion distributed optical fiber sensing system and data processing method

Abstract

The present invention discloses a Rayleigh-Raman fusion type distributed optical fiber sensing system and a data processing method. A narrow line width laser is used as a light source, a switch type semiconductor optical amplifier is used for pulse modulation, a photoelectric conversion and acquisition card with the same sampling rate is used to simultaneously receive a backward Rayleigh signal and a backward Raman signal, a variable time delay pulse pair is used for detection, and subsequent processing is performed after the backward Rayleigh scattered light is translated and aligned, and the backward Raman scattered light is subjected to cross recombination, smoothing noise reduction and deconvolution calculation to achieve an increase in the sampling rate, and finally the temperature field is reconstructed through the temperature curve of the pulse pair to achieve an improvement in the spatial resolution of the temperature measurement of the fusion system, the hardware is highly integrated, the main technical indicators are not affected, and the common single-mode optical fiber distributed vibration temperature simultaneous monitoring can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of distributed optical fiber sensing, and in particular to a Rayleigh-Raman fusion type distributed optical fiber sensing system and a data processing method. Background Art

[0002] Distributed fiber optic sensing technology is particularly suitable for the safety monitoring of buried pipelines such as oil, gas, water, electricity, and networks due to its continuous multi-point detection, long monitoring distance, and easy installation. At present, phase-sensitive optical time-domain reflectometers are generally used to detect vibration signals along the optical cable laid along the buried pipeline, accurately locate and warn of mechanical construction and human damage near the pipeline, and prevent possible leakage accidents in the bud in a timely manner.

[0003] When an actual accident occurs, multiple physical parameters always change simultaneously. Therefore, it is difficult to accurately warn or locate the event by detecting only a single physical quantity. Therefore, it is very meaningful to realize distributed vibration and temperature simultaneous monitoring. The existing fusion system methods either use multi-core optical fibers or the technical indicators of the fusion system are seriously degraded, and ordinary single-mode optical fibers cannot be used to realize distributed vibration and temperature simultaneous monitoring. Summary of the invention

[0004] The purpose of the present invention is to provide a Rayleigh-Raman fusion type distributed optical fiber sensing system and a data processing method to realize the simultaneous monitoring of the distributed vibration and temperature of ordinary single-mode optical fiber.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present invention provides a Rayleigh-Raman fusion type distributed optical fiber sensing system, which includes a narrow linewidth laser, a switch-type semiconductor optical amplifier, an erbium-doped optical fiber amplifier, an optical fiber circulator, a wavelength division multiplexer, a calibration component, a sensing optical cable, a multi-stage amplification circuit, a multi-channel acquisition card and an industrial computer. The narrow linewidth laser, the switch-type semiconductor optical amplifier, the erbium-doped optical fiber amplifier, the optical fiber circulator, the wavelength division multiplexer, the calibration component and the sensing optical cable are connected in sequence, the multi-stage amplification circuit is connected to the optical fiber circulator and the wavelength division multiplexer, and the multi-stage amplification circuit, the multi-channel acquisition card and the industrial computer are connected in sequence.

[0006] The Rayleigh-Raman fusion distributed optical fiber sensing system further comprises a pulse width and delay control module, and the pulse width and delay control module is respectively connected to the switch-type semiconductor optical amplifier and the multi-channel acquisition card.

[0007] Wherein, the calibration component includes a calibration optical fiber and a thermistor, the calibration optical fiber is connected to the wavelength division multiplexer and the sensing optical cable, and the thermistor is connected to the industrial computer.

[0008] The optical fiber circulator has a first port, a second port and a third port, the first port is connected to the erbium-doped fiber amplifier, the second port is connected to the wavelength division multiplexer, and the third port is connected to the multi-stage amplifier circuit.

[0009] The wavelength division multiplexer has a fourth port and a fifth port, and both the fourth port and the fifth port are connected to the multi-stage amplification circuit.

[0010] In a second aspect, the present invention provides a data processing method for a Rayleigh-Raman fusion type distributed optical fiber sensing system, which is applicable to the Rayleigh-Raman fusion type distributed optical fiber sensing system as described in the first aspect, and comprises the following steps:

[0011] The pulse width and delay control module drives the switch-type semiconductor optical amplifier to generate pulse pairs with different delays. After multiple groups of pulse pairs are transmitted, they enter the sensor optical cable to generate backward Rayleigh scattered light and backward Raman scattered light.

[0012] After obtaining the backscattered Rayleigh light, each group of pulse pairs is aligned with corresponding time delay translation, and the two groups of original data curves obtained are subjected to noise reduction processing, and then disturbance waveforms are superimposed, and the combined disturbance waveforms are used for alarming;

[0013] After the back Raman scattered light is obtained, multiple groups of the back Raman scattered light are cross-recombined, smoothed, de-noised and deconvoluted, and the temperature curve obtained by temperature demodulation is reconstructed using pulse width.

[0014] The invention discloses a Rayleigh-Raman fusion type distributed optical fiber sensing system and data processing method. A narrow line width laser is used as a light source, a switch type semiconductor optical amplifier is used for pulse modulation, a photoelectric conversion and acquisition card with the same sampling rate is used to simultaneously receive a backward Rayleigh signal and a backward Raman signal, a variable time delay pulse pair is used for detection, and subsequent processing is performed after the backward Rayleigh scattered light is translated and aligned. The backward Raman scattered light is subjected to cross recombination, smooth noise reduction and deconvolution calculation to achieve an increase in the sampling rate. Finally, the temperature field is reconstructed through the temperature curve of the pulse pair to achieve an improvement in the spatial resolution of the temperature measurement of the fusion system. The hardware is highly fused, the main technical indicators are not affected, and the common single-mode optical fiber distributed vibration temperature simultaneous monitoring can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 It is a structural schematic diagram of a Rayleigh-Raman fusion type distributed optical fiber sensing system provided by the present invention.

[0017] Figure 2 It is a schematic diagram of sampling of variable time-delay pulse pairs provided by the present invention.

[0018] Figure 3 It is a schematic diagram of backscattering data processing provided by the present invention.

[0019] Figure 4 It is a schematic diagram of back Raman scattering data processing provided by the present invention.

[0020] Figure 5 It is a schematic diagram of the steps of a data processing method of a Rayleigh-Raman fusion distributed optical fiber sensing system provided by the present invention.

[0021] 1- narrow linewidth laser, 2- switch type semiconductor optical amplifier, 3- erbium-doped fiber amplifier, 4- fiber circulator, 5- wavelength division multiplexer, 6- calibration fiber, 7- thermistor, 8- sensor cable, 9- multi-stage amplifier circuit, 10- multi-channel acquisition card, 11- pulse width and delay control module, 12- industrial computer, 41- first port, 42- second port, 43- third port, 51- fourth port, 52- fifth port. DETAILED DESCRIPTION

[0022] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0023] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 limiting the present invention. In addition, in the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0024] See also Figure 1 The present invention provides a Rayleigh-Raman fusion type distributed optical fiber sensing system, which includes a narrow linewidth laser 1, a switch type semiconductor optical amplifier 2, an erbium-doped optical fiber amplifier 3, an optical fiber circulator 4, a wavelength division multiplexer 5, a calibration component, a sensing optical cable 8, a multi-stage amplification circuit 9, a multi-channel acquisition card 10 and an industrial computer 12. The narrow linewidth laser 1, the switch type semiconductor optical amplifier 2, the erbium-doped optical fiber amplifier 3, the optical fiber circulator 4, the wavelength division multiplexer 5, the calibration component and the sensing optical cable 8 are connected in sequence, the multi-stage amplification circuit 9 is connected to the optical fiber circulator 4 and the wavelength division multiplexer 5, and the multi-stage amplification circuit 9, the multi-channel acquisition card 10 and the industrial computer 12 are connected in sequence.

[0025] In this embodiment, the sampling rates of the multi-channel APD and the multi-stage amplifier circuit 9 and the multi-channel acquisition card 10 are all 40MHz; the switch-type semiconductor optical amplifier 2 receives the emitted electrical pulse signal, modulates the continuous light emitted by the narrow linewidth laser 1 into a laser pulse signal of corresponding width, and then amplifies the optical pulse through the erbium-doped fiber amplifier 3, passes through the optical fiber circulator 4, the 1450nm / 1550nm / 1660nm wavelength division multiplexer 5 and the calibration component, and then enters the sensor optical cable 8. As the optical pulse is transmitted forward in the optical cable, it will interact with the sensor optical cable 8. Backward Rayleigh scattered light and backward Raman scattered light are generated. The backscattered light returns along the original route. After being filtered by the 1450 / 1550 / 1660 wavelength division multiplexer 5, the backrayleigh scattered light is emitted through the third port of the optical fiber circulator 4, and the backraman scattered light is emitted from two ports of the 1450 / 1550 / 1660 wavelength division multiplexer 5 respectively. The three-way sensor light signals are photoelectrically converted and amplified by the multi-channel APD and multi-stage amplifier circuit 9, and then transmitted to the acquisition card for analog-to-digital conversion and data acquisition. Finally, the data is transmitted to the industrial computer 12 for data processing.

[0026] The sampling rates of the multi-channel APD and multi-stage amplification circuit 9 and the multi-channel acquisition card 10 are all 40MHz. The pulse width and delay control module 11 drives the switch-type semiconductor optical amplifier 2 to generate pulse pairs for different tests. The pulse widths of the pulse pairs are 100ns and 105ns respectively. On the basis of the first group of pulse pairs, the next four groups of pulse pairs are delayed by 25ns in sequence for pulse triggering. After the fifth group of pulse pairs is emitted, the cycle starts from the first group. When the sampling start time remains unchanged, it is equivalent to delayed sampling.

[0027] Furthermore, the Rayleigh-Raman fusion distributed optical fiber sensing system further includes a pulse width and delay control module 11, and the pulse width and delay control module 11 is connected to the switch-type semiconductor optical amplifier 2 and the multi-channel acquisition card 10 respectively.

[0028] In this embodiment, the pulse width and delay control module 11 sends an electrical pulse signal to the switch-type semiconductor optical amplifier 2 to modulate the continuous light emitted by the narrow linewidth laser 1 into a laser pulse signal of corresponding width.

[0029] Furthermore, the calibration component includes a calibration optical fiber 6 and a thermistor 7 , wherein the calibration optical fiber 6 is connected to the wavelength division multiplexer 5 and the sensing optical cable 8 , and the thermistor 7 is connected to the industrial computer 12 .

[0030] In this embodiment, the calibration optical fiber 6 and the thermistor 7 are used for real-time calibration during temperature demodulation of the Raman optical time domain reflectometer.

[0031] Furthermore, the optical fiber circulator 4 has a first port 41 , a second port 42 and a third port 43 , the first port 41 is connected to the erbium-doped fiber amplifier 3 , the second port 42 is connected to the wavelength division multiplexer 5 , and the third port 43 is connected to the multi-stage amplifier circuit 9 .

[0032] In this embodiment, the first port 41 receives the signal amplified by the erbium-doped fiber amplifier 3 , the second port 42 transmits the signal passing through the fiber circulator 4 to the calibration fiber 6 , and the third port 43 emits the backward Rayleigh scattered light to the multi-stage amplifier circuit 9 .

[0033] Furthermore, the wavelength division multiplexer 5 has a fourth port 51 and a fifth port 52 , and both the fourth port 51 and the fifth port 52 are connected to the multi-stage amplifier circuit 9 .

[0034] In this embodiment, the fourth port 51 is a 1660 port and the fifth port 52 is a 1450 port, and their main function is to emit the backward Raman scattered light to the multi-stage amplification circuit 9 .

[0035] See also Figure 5The present invention provides a data processing method for a Rayleigh-Raman fusion type distributed optical fiber sensing system, which is applicable to the Rayleigh-Raman fusion type distributed optical fiber sensing system, and comprises the following steps:

[0036] S101, driving the switch-type semiconductor optical amplifier 2 to generate pulse pairs with different delays through the pulse width and delay control module 11, until multiple groups of pulse pairs are transmitted, and enter the sensor optical cable 8 to generate backward Rayleigh scattered light and backward Raman scattered light.

[0037] Specifically, the sampling rates of the multi-channel APD and multi-stage amplifier circuit 9 and the multi-channel acquisition card 10 are the same. The pulse width and delay control module 11 drives the switch-type semiconductor optical amplifier 2 to generate pulse pairs with different delays. The pulse widths of the pulse pairs are T and T+ΔT respectively. Based on the first group of pulse pairs, the subsequent pulse pairs are sequentially delayed by Δt for pulse triggering. Δt should be an integer multiple of the acquisition card sampling rate. After the Nth group of pulse pairs is emitted, the cycle starts from the first group. When the sampling start time remains unchanged, it is equivalent to delayed sampling. Figure 2 As shown, the pulse widths of the pulse pairs are 100ns and 105ns respectively. Based on the first group of pulse pairs, the next four groups of pulse pairs are delayed by 25ns in sequence for pulse triggering. After the fifth group of pulse pairs is emitted, the cycle starts from the first group. When the sampling start time remains unchanged, it is equivalent to delayed sampling.

[0038] S102, after obtaining the backward Rayleigh scattered light, aligning the corresponding time delays of the pulse pairs, performing noise reduction processing on the two sets of original data curves, and then superimposing disturbance waveforms, and using the combined disturbance waveforms to issue an alarm.

[0039] Specifically, after obtaining the backscattered Rayleigh light, each group of pulse pairs is aligned with corresponding time delay shifts, such as Figure 3 As shown in the figure, two groups of φ-OTDR raw data curves corresponding to different pulse widths are obtained. First, the raw signals of the two groups of pulse widths are subjected to sliding average noise reduction processing, and then the average algorithm is used to continue noise reduction and reduce the amount of data processing. Then the disturbance curve is calculated using the difference algorithm and noise reduction is performed using wavelet decomposition. Since a small change in pulse width will not affect the change in vibration position, the disturbance waveforms obtained from two different pulse widths can be superimposed at this time. Finally, the combined disturbance waveform is used for alarm, and the vibration signal matrix near the corresponding position is intercepted to use machine learning to determine the type of event that causes the disturbance.

[0040] S103, after obtaining the back Raman scattered light, cross-recombining, smoothing, denoising and deconvolution calculation are performed on multiple groups of the back Raman scattered light, and the temperature curve obtained by temperature demodulation is reconstructed using pulse width.

[0041] Specifically, after obtaining the back Raman scattered light, since the time delay of N groups of pulse pairs increases Δt in sequence, a set of data with N times the photoelectric conversion and acquisition card sampling rate can be obtained by cross-recombining, smoothing, denoising and deconvolution calculation of N groups of back Raman scattered light, thus obtaining Stokes Raman scattering signals and anti-Stokes Raman scattering signals with N times the sampling rate corresponding to T and T+ΔT pulse widths. The temperature curve corresponding to T and T+ΔT pulse widths is obtained by temperature demodulation, and finally the temperature curve corresponding to ΔT pulse width is reconstructed using the temperature curve corresponding to T and T+ΔT pulse width, thereby improving the spatial resolution of temperature measurement in the fusion system.

[0042] like Figure 4 As shown in the figure, since the delay of the five pulse pairs increases by 25ns, which corresponds to the interval of one sampling point of the 40MHz sampling rate, a set of 200MHz sampling data can be obtained by using five sets of 40MHz sampling data with a delay of one sampling point, and through cross-recombination, smoothing and noise reduction and deconvolution calculation of five sets of 40MHz backward Raman signals, so that the Stokes Raman scattering signal and anti-Stokes Raman scattering signal corresponding to the 200MHz sampling of 100ns and 105ns pulse width can be calculated. The temperature curve corresponding to the pulse width of 100ns and 105ns is obtained through temperature demodulation, and finally the temperature curve corresponding to the pulse width of 100ns and 105ns is used to reconstruct the temperature curve of the 5ns pulse width, so that the temperature measurement spatial resolution of the fusion system reaches 0.5m.

[0043] The invention discloses a Rayleigh-Raman fusion type distributed optical fiber sensing system and data processing method. A narrow line width laser is used as a light source, a switch type semiconductor optical amplifier is used for pulse modulation, a photoelectric conversion and acquisition card with the same sampling rate is used to simultaneously receive a backward Rayleigh signal and a backward Raman signal, a variable time delay pulse pair is used for detection, and subsequent processing is performed after the backward Rayleigh scattered light is translated and aligned. The backward Raman scattered light is subjected to cross recombination, smooth noise reduction and deconvolution calculation to achieve an increase in the sampling rate. Finally, the temperature field is reconstructed through the temperature curve of the pulse pair to achieve an improvement in the spatial resolution of the temperature measurement of the fusion system. The hardware is highly fused, the main technical indicators are not affected, and the common single-mode optical fiber distributed vibration temperature simultaneous monitoring can be achieved.

[0044] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A data processing method for a Rayleigh-Raman fusion distributed optical fiber sensing system, It is characterized in that The Rayleigh-Raman fusion type distributed optical fiber sensing system comprises a narrow line width laser, a switch type semiconductor optical amplifier, an erbium-doped optical fiber amplifier, an optical fiber circulator, a wavelength division multiplexer, a calibration component, a sensing optical cable, a multi-stage amplification circuit, a multi-channel acquisition card and an industrial computer. The narrow line width laser, the switch type semiconductor optical amplifier, the erbium-doped optical fiber amplifier, the optical fiber circulator, the wavelength division multiplexer, the calibration component and the sensing optical cable are connected in sequence, the multi-stage amplification circuit is connected to the optical fiber circulator and the wavelength division multiplexer, and the multi-stage amplification circuit, the multi-channel acquisition card and the industrial computer are connected in sequence; The Rayleigh-Raman fusion type distributed optical fiber sensing system further comprises a pulse width and delay control module, wherein the pulse width and delay control module are respectively connected to the switch type semiconductor optical amplifier and the multi-channel acquisition card; The data processing method of the Rayleigh-Raman fusion distributed optical fiber sensing system comprises the following steps: The pulse width and delay control module is used to drive the switch-type semiconductor optical amplifier to generate pulse pairs with different delays. The pulse widths of the pulse pairs are T and T+ΔT respectively. Based on the first group of pulse pairs, the subsequent pulse pairs are sequentially delayed by Δt for pulse triggering. Δt should be an integer multiple of the sampling rate of the acquisition card. After the Nth group of pulse pairs is emitted, the cycle starts from the first group. When the sampling start time remains unchanged, it is equivalent to delayed sampling. After multiple groups of pulse pairs are emitted, they enter the sensor optical cable to generate backward Rayleigh scattered light and backward Raman scattered light. After obtaining the backscattered Rayleigh light, each group of pulse pairs is aligned with corresponding time delay translation, and the two groups of original data curves obtained are subjected to noise reduction processing, and then disturbance waveforms are superimposed, and the combined disturbance waveforms are used for alarming; Since the time delay of N groups of pulse pairs increases successively by Δt, a set of data with N times the photoelectric conversion and acquisition card sampling rate can be obtained by cross-recombining, smoothing, denoising and deconvolution calculation of N groups of backward Raman scattered light, and the Stokes Raman scattering signal and anti-Stokes Raman scattering signal with N times the sampling rate corresponding to the pulse width of T and T+ΔT can be obtained; the temperature curve corresponding to the pulse width of T and T+ΔT can be obtained by temperature demodulation, and finally the temperature curve corresponding to the pulse width of T and T+ΔT can be used to reconstruct the temperature curve of the ΔT pulse width, thereby improving the spatial resolution of temperature measurement in the fusion system.

2. The data processing method of the Rayleigh-Raman fusion distributed optical fiber sensing system according to claim 1, It is characterized in that The calibration component comprises a calibration optical fiber and a thermistor. The calibration optical fiber is connected to the wavelength division multiplexer and the sensing optical cable, and the thermistor is connected to the industrial computer.

3. The data processing method of the Rayleigh-Raman fusion distributed optical fiber sensing system according to claim 1, It is characterized in that The optical fiber circulator has a first port, a second port and a third port. The first port is connected to the erbium-doped fiber amplifier, the second port is connected to the wavelength division multiplexer, and the third port is connected to the multi-stage amplifier circuit.

4. The data processing method of the Rayleigh-Raman fusion distributed optical fiber sensing system according to claim 1, It is characterized in that The wavelength division multiplexer has a fourth port and a fifth port, and both the fourth port and the fifth port are connected to the multi-stage amplification circuit.

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