CN111103067A - Cable trench temperature monitoring method and system based on single-mode optical fiber - Google Patents
Cable trench temperature monitoring method and system based on single-mode optical fiber Download PDFInfo
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- CN111103067A CN111103067A CN201911360342.3A CN201911360342A CN111103067A CN 111103067 A CN111103067 A CN 111103067A CN 201911360342 A CN201911360342 A CN 201911360342A CN 111103067 A CN111103067 A CN 111103067A
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- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
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- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K1/00—Details of thermometers not specially adapted for particular types of thermometer
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- G01K1/024—Means for indicating or recording specially adapted for thermometers for remote indication
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- G—PHYSICS
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- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
- G01K11/324—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres using Raman scattering
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Abstract
The invention relates to a cable trench temperature monitoring method based on a single mode fiber, which is applied to a cable trench temperature detection system, wherein the cable trench temperature detection system comprises the single mode fiber which is arranged in the same trench as a cable to be detected, and the method comprises the following steps: coupling a laser signal of a preset power to the single-mode optical fiber to generate Raman scattered light in the single-mode optical fiber; receiving the Raman scattered light, and demodulating and separating the received Raman scattered light to obtain anti-Stokes scattered light carrying temperature information; acquiring temperature information distributed along the cable to be tested according to the laser signal and the anti-Stokes scattered light; when the temperature information of the cable to be tested is abnormal, an alarm signal is output, the temperature of the cable to be tested in a long distance can be automatically monitored, and repeated investment and waste of additionally laying the multimode temperature measurement optical cable can be avoided.
Description
Technical Field
The invention relates to the technical field of temperature monitoring, in particular to a cable duct temperature monitoring method and system based on single-mode optical fibers.
Background
The cables in the cable trench are wide in distribution and long in distance, and faults such as cable breakage, short circuit, equipment tripping, power failure and the like caused by fire cause economic loss to power users and also form serious threats to safe operation of a power grid
Conventionally, a temperature monitoring method for a power cable may be based on a temperature sensing cable type temperature measuring system, in which two or more elastic steel wires made of a thermal insulation material are coated inside a temperature sensing cable, and when a monitored external environment temperature reaches a predetermined melting temperature of the insulation material, an insulation layer of the cable is damaged to cause a short circuit. However, the system is inconvenient to install and maintain, has a short monitoring distance, and is easily subjected to electromagnetic interference.
Disclosure of Invention
Therefore, in order to solve the above problems, it is necessary to provide a cable duct temperature monitoring method and system based on a single mode fiber, which can automatically monitor the temperature of a long-distance cable to be measured and avoid the repeated investment and waste of additionally laying a multimode temperature measurement cable.
The utility model provides a cable pit temperature monitoring method based on single mode fiber, is applied to cable pit temperature detecting system, cable pit temperature detecting system includes the single mode fiber with the ditch setting of the cable that awaits measuring, the method includes:
coupling a laser signal of a preset power to the single-mode optical fiber to generate Raman scattered light in the single-mode optical fiber;
receiving the Raman scattered light, and demodulating and separating the received Raman scattered light to obtain anti-Stokes scattered light carrying temperature information;
acquiring temperature information distributed along the cable to be tested according to the laser signal and the anti-Stokes scattered light;
and when the temperature information of the cable to be detected is abnormal, outputting an alarm signal.
Before acquiring the temperature information of the cable to be measured according to the laser signal and the anti-stokes scattered light, the method further comprises the following steps:
demodulating and separating the received Raman scattered light to obtain Stokes scattered light;
eliminating random losses in the single mode fiber from the Stokes scattered light and the anti-Stokes light.
In one embodiment, the eliminating random loss in the single mode fiber according to the stokes scattered light and anti-stokes light comprises:
acquiring the light intensity ratio of the anti-Stokes light to the Stokes scattered light;
and eliminating random loss in the single-mode optical fiber according to the light intensity ratio.
In one embodiment, before outputting the alarm signal when the temperature information of the cable to be tested is abnormal, the method further includes:
constructing a preset temperature correction model;
and correcting the temperature information of each temperature test point of the cable to be tested according to the preset temperature correction model.
In one embodiment, the constructing the preset temperature correction model includes:
acquiring a plurality of calibration temperatures of the cable to be tested at different preset distances from the temperature test points to the cable to be tested based on a temperature sensor;
establishing a corresponding relation between the preset distance and the calibration temperature at each temperature test point;
and constructing a preset temperature correction model according to the corresponding relation between the preset distance and the calibration temperature corresponding to the plurality of temperature test points.
In one embodiment, the outputting an alarm signal when the temperature information of the cable to be tested is abnormal includes:
when any temperature information distributed along the cable to be tested is higher than a preset temperature, the temperature abnormal point of the cable to be tested is positioned and the alarm signal is output, and the alarm signal carries the position information of the temperature abnormal point of the cable to be tested.
In one embodiment, the method further comprises:
drawing a virtual map of the cable to be tested according to the distribution information of the cable to be tested;
and displaying temperature information distributed along the cable to be tested on the virtual map.
The embodiment of the application still provides a cable pit temperature detecting system based on single mode fiber, its characterized in that, be used for right the temperature information of the cable that awaits measuring detects, the system includes:
the single-mode optical fiber is arranged in the same groove with the cable to be tested;
the light source module is coupled with the single-mode optical fiber and used for coupling a laser signal with preset power to the single-mode optical fiber so as to generate Raman scattering light in the single-mode optical fiber;
the optical detection module is coupled with the single-mode optical fiber and used for receiving the Raman scattering light, demodulating and separating the received Raman scattering light to obtain anti-Stokes scattering light carrying temperature information and realize photoelectric conversion;
the processing module is respectively connected with the light source module and the light detection module and used for acquiring temperature information distributed along the cable to be detected according to the laser signal and the anti-Stokes scattered light and outputting an alarm instruction when the temperature information of the cable to be detected is abnormal;
and the alarm module is connected with the processing module and used for receiving the alarm instruction and executing sound-light alarm operation according to the alarm instruction.
In one embodiment, the processing module comprises:
the conversion unit is connected with the optical detection module and used for receiving an electric signal and carrying out analog-to-digital conversion on the electric signal;
the processing unit is connected with the conversion unit and used for acquiring temperature information distributed along the cable to be tested according to the electric signal converted by the analog-digital conversion;
and the optical time domain reflection processing unit is connected with the light source module and the optical detection module and is used for positioning the temperature abnormal point of the cable to be detected so as to acquire the position information of the temperature abnormal point.
In one embodiment, the system further comprises:
the map display module is connected with the optical time domain reflection processing unit and used for drawing a virtual map of the cable to be tested according to the distribution information of the cable to be tested; and marking the position information on the virtual map, and displaying the marked virtual map.
According to the cable trench temperature monitoring method and system based on the single-mode optical fiber, a laser signal with preset power can be coupled to the single-mode optical fiber to generate Raman scattering light in the single-mode optical fiber; receiving the Raman scattered light, and demodulating and separating the received Raman scattered light to obtain anti-Stokes scattered light carrying temperature information; acquiring temperature information distributed along the cable to be tested according to the laser signal and the anti-Stokes scattered light; and when the temperature information of the cable to be detected is abnormal, outputting an alarm signal. Wherein, this single mode fiber is the one-core fiber of standard multicore communication optical cable, can easily realize the sharing of optical cable resource, has avoided additionally laying the repeated input and the waste of multimode temperature measurement optical cable, can carry out automatic monitoring to the temperature of long distance cable that awaits measuring simultaneously, has promoted the alarming performance, simultaneously greatly reduced artifical the participation, reduced the human cost.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and those skilled in the art will be able to derive drawings of other embodiments from these drawings without creative efforts.
FIG. 1 is a flow chart of a single mode fiber based cable trench temperature monitoring method in one embodiment;
FIG. 2 is a flow chart illustrating the construction of the predetermined temperature correction model according to one embodiment;
fig. 3 is a structural framework diagram of a single-mode fiber-based cable duct temperature monitoring method in one embodiment.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, and in order to provide a better understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete. This invention can be embodied in many different forms than those herein described and many modifications may be made by those skilled in the art without departing from the spirit of the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise. In the description of the present invention, "a plurality" means at least one, e.g., one, two, etc., unless specifically limited otherwise.
The embodiment of the application provides a cable trench temperature monitoring method based on single mode fibers, which is applied to a cable trench temperature detection system, wherein the cable trench temperature detection system comprises the single mode fibers which are arranged in the same trench as a cable to be detected. When the single-mode optical fiber is used as a temperature sensing medium for temperature detection, a standard multi-core communication optical cable can be adopted, the single-mode optical fiber only occupies one core optical fiber of the multi-core communication optical cable, and the rest cores can be used for expanding optical communication and can be continuously used for expanding and compatible functions of safety monitoring systems such as a cable anti-theft positioning monitoring system based on an optical fiber vibration sensing technology. The conventional standard multi-core communication optical cable is mostly 4-96 cores, the single-mode fiber-based cable trench temperature monitoring method only occupies one core fiber in the multi-core communication optical cable, the sharing of optical cable resources can be easily realized, and the repeated investment and waste of independently laying multi-mode temperature measurement optical cables are avoided. Meanwhile, the single-mode fiber-based temperature monitoring has the advantages of more stable performance, longer monitoring distance, compatibility with an optical communication line, adaptation to the development trend of composite cables, wider application range and the like due to the communication advantages of the single-mode fiber. The method has the advantages of reducing the complexity of the system and the input cost when being applied in a large range, and simultaneously reserving space for system expansion.
As shown in fig. 1, in one embodiment, the method for monitoring the temperature of a cable trench based on a single mode fiber comprises steps 102 to 108. Wherein the content of the first and second substances,
In one embodiment, the light source module of the cable trench temperature system (referred to as the system in the embodiment of the present application) based on single-mode fiber emits a laser signal with a preset power. The light source module is used for emitting laser signals, is coupled with the single-mode optical fiber, and can couple the emitted laser signals to the single-mode optical fiber and transmit the laser signals in the single-mode optical fiber. The laser signal may be narrow linewidth laser pulse light. When the pulse power of the narrow-linewidth laser pulse light reaches a certain threshold value, Raman scattering light (Raman scattering light) is generated in the single-mode fiber.
The physical interaction of the laser signal and the fiber molecules produces raman scattered light. Specifically, when a photon collides with a substance molecule, the photon energy is changed by transferring part of the energy to or from the substance molecule while the photon movement direction is changed. The former reduces photon energy, with longer wavelengths than incident light; the latter increases the photon energy, with a shorter wavelength than the incident light, both of which are referred to as raman scattered light.
And 104, receiving the Raman scattering light, and demodulating and separating the received Raman scattering light to obtain anti-Stokes scattering light carrying temperature information.
When a laser signal generates Raman scattered light in a single-mode fiber, a light detection module of the system correspondingly receives the reflected Raman scattered light, demodulates and separates the received Raman scattered light, and decomposes the received Raman scattered light into Stokes light and anti-Stokes light with different wavelengths. Among these, in raman scattered light, a spectral line having a frequency lower than the frequency of incident light is referred to as a stokes line, and a spectral line having a frequency higher than the frequency of incident light is referred to as an anti-stokes line. The intensity of the anti-stokes light is strongly related to the temperature of the transmission medium, whereas the intensity of the stokes light is weakly related to the temperature of the transmission medium.
And 106, acquiring temperature information distributed along the cable to be detected according to the laser signals and the anti-Stokes scattered light.
In one embodiment, the system can calculate the temperature profile along the single mode fiber based on the two optical signals, i.e., the transmitted laser signal and the received anti-stokes light. Because the single mode fiber and the cable to be tested are arranged in the same channel and are parallel to each other and are closely arranged, the temperature curve distributed by the single mode fiber can be used as the temperature information distributed along the cable to be tested.
Specifically, the distribution curve of the temperature along the optical fiber can be calculated based on the photoelectric conversion, digital-to-analog conversion, and other processing and comparison of the laser signal and the received anti-stokes light. Illustratively, along a single mode fiber, one test point may be placed every 10cm, which takes a step of 10cm of the temperature profile along the single mode fiber.
And step 108, outputting an alarm signal when the temperature information of the cable to be tested is abnormal.
The system can obtain the temperature information of the cable to be tested, compare the obtained temperature information with a temperature threshold value, and when the temperature information is higher than the temperature threshold value, the system can indicate that the temperature information of the cable to be tested is abnormal, and at the moment, corresponding alarm signals can be correspondingly output to prompt maintenance personnel to check the cable so as to eliminate potential safety hazards caused by overhigh temperature.
The method for monitoring the temperature of the cable duct based on the single-mode optical fiber in the embodiment comprises the following steps: coupling a laser signal of a preset power to the single-mode optical fiber to generate Raman scattered light in the single-mode optical fiber; receiving the Raman scattered light, and demodulating and separating the received Raman scattered light to obtain anti-Stokes scattered light carrying temperature information; acquiring temperature information distributed along the cable to be tested according to the laser signal and the anti-Stokes scattered light; and when the temperature information of the cable to be detected is abnormal, outputting an alarm signal. Wherein, this single mode fiber is the one-core fiber of standard multicore communication optical cable, can easily realize the sharing of optical cable resource, has avoided additionally laying the repeated input and the waste of multimode temperature measurement optical cable, can carry out automatic monitoring to the temperature of long distance cable that awaits measuring simultaneously, has promoted the alarming performance, simultaneously greatly reduced artifical the participation, reduced the human cost.
In one embodiment, the outputting an alarm signal when the temperature information of the cable to be tested is abnormal includes: and when any temperature information distributed along the cable to be detected is higher than a preset temperature, positioning a temperature abnormal point of the cable to be detected and outputting the alarm signal, wherein the alarm signal carries the position information of the temperature abnormal point of the cable to be detected.
In one embodiment, before acquiring the temperature information of the cable to be measured according to the laser signal and the anti-stokes scattered light, the method further includes: demodulating and separating the received Raman scattered light to obtain Stokes scattered light; eliminating random losses in the single mode fiber from the Stokes scattered light and the anti-Stokes light.
The random loss can include microbending loss caused by micro-concave-convex on the interface of the fiber core and the cladding due to the fact that the side surface of the optical fiber receives uneven pressure and micron-scale bending occurs in the axial direction; the radius of curvature of the fiber bend is small, bending loss due to light leakage into the cladding, and the like.
The method can eliminate random loss in the single-mode optical fiber according to the Stokes scattered light and the anti-Stokes light, and specifically comprises the following steps: acquiring the light intensity ratio of the anti-Stokes light to the Stokes scattered light; and eliminating random loss in the single-mode optical fiber according to the light intensity ratio. Specifically, the influence of the random loss on the stokes light and the anti-stokes light is the same, and since the anti-stokes light carries the temperature information of the single-mode fiber, the first light intensity information of the anti-stokes light is correspondingly obtained, the second light intensity information of the stokes light is obtained, the light intensity ratio of the first light intensity information to the second light intensity information is calculated, and then the random loss in the single-mode fiber can be eliminated according to the light intensity ratio.
In one embodiment, before outputting the alarm signal when the temperature information of the cable to be tested is abnormal, the method further includes: and constructing a preset temperature correction model, and correcting the temperature information of each temperature test point of the cable according to the preset temperature correction model. That is, when the temperature information of each temperature test point of the cable to be tested is obtained, the obtained temperature information can be corrected based on the preset temperature correction model so as to improve the accuracy of the temperature information of the cable to be tested.
Specifically, the preset temperature correction model is constructed, and comprises steps 202 to 208. Wherein:
A plurality of temperature test points can be arranged along the cable to be tested, the number of the temperature test points is less than or equal to that of the test points of the single-mode optical fibers, and each temperature test point can be arranged corresponding to the test point of the single-mode optical fiber. Specifically, the temperature test points may be arranged according to the environment around the cable to be tested, for example, the temperature test points may be arranged densely in areas with large commercial and pedestrian traffic, and the temperature test points may be arranged sparsely in areas with small pedestrian traffic and buildings. Illustratively, if N test points arranged in the single-mode fiber are equal in distance between two adjacent test points, and both the distances are 10cm, any M of the N test points may be used as the temperature test points of the cable to be tested, where N is greater than or equal to M, and the distribution of the M temperature test points may be set according to the environment around the cable to be tested, that is, the distances between two adjacent temperature test points may be equal or unequal. In the present application, the selection of the M temperature test points is not further limited.
For example, the M temperature test points can be respectively marked as T1-TMWherein, the ith temperature test point is TiAnd (4) showing. At each temperature test point, a temperature sensor may be arranged to measure a calibration temperature of the cable to be measured at the area of the current measurement point. Specifically, at each measurement point, a temperature sensor may be placed at a different predetermined distance from the cable to be measured to measure the corresponding calibration temperature. Illustratively, the preset distance may be 0, 1cm, 2cm, 3cm, 4cm, and so forth. When the preset distance is Q, the temperature is measured at the same temperature measuring point TiAnd correspondingly acquiring Q calibration temperatures of different preset distances.
It should be noted that the preset distance refers to a shortest distance from the cable to be tested, where the temperature test point is disposed on the cable to be tested. When the preset distance is 0, the temperature sensor is arranged at the temperature test point of the cable to be tested.
And 204, establishing a corresponding relation between the preset distance and the calibration temperature at each temperature test point.
In one embodiment, the calibration temperatures above the temperature threshold are removed from the plurality of calibration temperatures and the remaining calibration temperatures are used as the data set. In the data set, at each temperature test point TiAnd establishing a corresponding relation between a preset distance and the calibration temperature. In particular, theThe corresponding relation can be Ti(t)＝fi(D) L, wherein, fi(D) Is the coefficient of the current temperature test point, L is the preset distance, Ti(t) is the calibration temperature at the preset distance. f. ofi(D) May be a fixed value or may be variable. F corresponding to different temperature test points due to different environments of the temperature test pointsi(D) The system may also be different.
The temperature threshold value is understood to be a critical value between a normal value and an abnormal value of the temperature value of the cable. By deleting the calibration temperature higher than the temperature threshold, all calibration temperatures of the data set can be temperatures within a normal range, and the established corresponding relation is more accurate.
And step 206, constructing a preset temperature correction model according to the corresponding relation between the preset distance and the calibration temperature corresponding to each of the plurality of temperature test points.
The system can correspondingly acquire the corresponding relation between the preset distances at different temperature test points and the calibration temperature, namely can correspondingly acquire the T1(t)＝f1(D)*L、T2(t)＝f2(D)*L、Ti(t)＝fi(D)*L、…、TM(t)＝fM(D) L. The system can obtain M corresponding relations Ti(t)＝fi(D) L constructing a preset temperature correction model. The constructed preset temperature correction model can include the corresponding relation among the temperature test point, the preset distance and the calibration temperature. For example, the correspondence relationship may be obtained by curve fitting, and the form of the correspondence relationship curve including the three parameters may take various curve forms.
In one embodiment, after the temperature information of the cable to be tested is acquired based on the single-mode fiber, the temperature information of each temperature test point of the cable to be tested can be corrected based on the preset temperature correction model.
Specifically, the system may correspondingly obtain temperature information of the single-mode fiber at each test point, and obtain distance information between the single-mode fiber and the cable to be tested, which is referred to as a first distance. Based on the preset temperature correction model, a calibration temperature corresponding to the first distance and each test point is determined, and the acquired temperature information can be calibrated according to the calibration temperature. For example, the system may correspond to a temperature profile that captures temperature information distributed along a single mode fiber. When the distance between the single mode fiber and the cable to be tested is the first distance, the calibration temperature curves distributed at the temperature test points at the first distance in the preset temperature correction model can be correspondingly obtained. The system may correct the temperature profile based on the calibrated temperature profile. For example, the calibration temperature curve and the temperature curve may be compared, an area with the same trend in the two curves is screened out, a difference value between the two curves in the area is obtained, the difference value is used as a compensation amount of the temperature information, and then the measured temperature information is compensated and calibrated according to the compensation amount.
In this embodiment, the method can calibrate the measured temperature information of the cable to be measured according to the preset temperature correction model, so as to improve the accuracy of the temperature information and further improve the accuracy of the early warning.
In one embodiment, the system can locate the temperature anomaly point of the cable to be measured based on the optical time domain reflection location principle. Specifically, when the laser signal is transmitted in the single-mode fiber, the anti-stokes light generated at different positions is reflected by the single-mode fiber at different time to reach the light detector, and the position of the anti-stokes light on the single-mode fiber can be obtained by multiplying the time difference between the anti-stokes light reaching the light detector and the light pulse laser signal emitted by the laser by the transmission speed of the light in the single-mode fiber and then dividing by 2. And then, the temperature abnormal point of the cable to be measured can be correspondingly positioned.
When the temperature abnormal point is located, an alarm signal can be correspondingly output, and meanwhile, the alarm signal carries the position information of the temperature abnormal point of the cable to be tested. The position information can also be represented by a test point of a single-mode optical fiber.
In one embodiment, the alarm signal may be presented in the form of sound, light, image, etc., and the specific form of the alarm signal is not further limited in this application.
In this embodiment, the method can locate the temperature anomaly point, and the alarm signal carries the position information of the temperature anomaly point, so that the maintenance personnel can quickly locate the temperature anomaly point, and then perform maintenance processing on the temperature anomaly point, thereby avoiding the occurrence of safety accidents caused by overhigh temperature.
In one embodiment, the method for monitoring the temperature of the cable duct based on the single-mode optical fiber further comprises the following steps: drawing a virtual map of the cable to be tested according to the distribution information of the cable to be tested; and marking the position information on the virtual map, and displaying the marked virtual map.
Specifically, the system can also draw a virtual map of the cable to be tested according to the distribution information of the cable to be tested. The virtual map may include information about the model of the cable to be tested, communication parameters, a laid line, an environment around the laid line (e.g., a building, a shop, etc.), and the like. When the temperature of the cable to be measured is abnormal, the temperature abnormal point can be positioned, the position information of the temperature abnormal point is marked on the virtual map, and the virtual map marked with the temperature abnormal point is displayed, so that maintenance personnel can quickly find the temperature abnormal point on the virtual map.
The embodiment of the application also provides a cable duct temperature detection system based on the single mode fiber, which is used for detecting the temperature information of the cable to be detected. As shown in fig. 3, in one embodiment, the system comprises: single mode fiber 310, light source module 320, light detection module 330, processing module 340, and alarm module 350.
And the single-mode optical fiber 310 is arranged in the same groove with the cable to be tested. When the single-mode fiber 310 is used as a temperature sensing medium for temperature detection, a standard multi-core communication cable can be adopted, the single-mode fiber 310 only occupies one core fiber of the multi-core communication cable, and the rest cores can be used for extended optical communication, so that the single-mode fiber 310 can be continuously used for the extended compatibility of functions of safety monitoring systems such as a cable anti-theft positioning monitoring system based on an optical fiber vibration sensing technology and the like. The conventional standard multi-core communication optical cable is mostly 4-96 cores, the single-mode fiber 310-based cable trench temperature monitoring method only occupies one core fiber in the multi-core communication optical cable, the sharing of optical cable resources can be easily realized, and the repeated investment and waste of independently laying multi-mode temperature measurement optical cables are avoided.
And a light source module 320 coupled to the single-mode fiber 310, configured to couple a laser signal with a preset power to the single-mode fiber 310 to generate raman scattered light in the single-mode fiber 310. The light source module 320 is configured to emit a laser signal, and the light source module 320 is coupled to the single-mode fiber 310, and can couple the emitted laser signal to the single-mode fiber 310 and transmit the laser signal in the single-mode fiber 310. The laser signal may be narrow linewidth laser pulse light. When the pulse power of the narrow-linewidth laser pulse light reaches a certain threshold, Raman scattering light (Raman scattering light) is generated in the single-mode fiber 310. For example, the light source module 320 may be a pulse laser, and the pulse laser may emit pulse light with a preset power and stability.
And the light detection module 330 is coupled to the single-mode fiber 310, and configured to receive the raman scattered light, and demodulate and separate the received raman scattered light to obtain anti-stokes scattered light carrying temperature information. For example, the light detection module 330 may be a photodetector, which can convert the received light signal into an electrical signal, and then output the electrical signal to the processing module 340 for processing.
And the processing module 340 is connected to the light source module 320 and the light detection module 330, and configured to acquire temperature information distributed along the cable to be tested according to the laser signal and the anti-stokes scattered light, and output an alarm instruction when the temperature information of the cable to be tested is abnormal.
And the alarm module 350 is connected to the processing module 340, and is configured to receive the alarm instruction and execute an audible and visual alarm operation according to the alarm instruction. For example, the alarm module 350 may include a display unit, a light emitting unit, a speaker, and the like capable of performing an audible and visual alarm operation. Wherein, the alarm signal can be presented in the form of sound, light and image.
The single-mode optical fiber 310, the light source module 320, and the light detection module 330 may be coupled and connected by the same coupler.
Above-mentioned cable pit temperature detecting system based on single mode fiber 310, single mode fiber 310 is a core optic fibre of standard multicore communication optical cable, can easily realize the sharing of optical cable resource, avoided laying the repeated input and the waste of multimode temperature measurement optical cable alone, simultaneously through setting up light source module 320, optical detection module 330, processing module 340 and alarm module 350, can carry out automatic monitoring to the temperature of long distance cable that awaits measuring, the alarm performance has been promoted, simultaneously greatly reduced artifical the participation, the human cost is reduced.
In one embodiment, the processing module 340 includes a conversion unit 341, a processing unit 342, and an optical time domain reflection processing unit 343. The conversion unit 341 is connected to the optical detection module 330, and is configured to receive an electrical signal and perform analog-to-digital conversion on the electrical signal; the processing unit 342 is connected to the conversion unit 341 and configured to obtain temperature information distributed along the cable to be tested according to the analog-to-digital converted electrical signal; the optical time domain reflection processing unit 343 is connected to the optical detection module 330 and the light source module 320, respectively, and is configured to position the temperature anomaly point of the cable to be detected to obtain the position information of the temperature anomaly point.
In one embodiment, the optical time domain reflection processing unit 343 may locate the temperature anomaly point of the cable to be measured based on the optical time domain reflection positioning principle. Specifically, when the laser signal is transmitted in the single-mode fiber 310, the anti-stokes light generated at different positions has different times of reaching the light detection module 330 along the reflection of the single-mode fiber 310, and the position of the anti-stokes light on the single-mode fiber 310 can be obtained by multiplying the time difference between the anti-stokes light reaching the light detection module 330 and the light pulse laser signal emitted by the laser by the transmission speed of the light in the single-mode fiber 310 and then dividing by 2. And then, the temperature abnormal point of the cable to be measured can be correspondingly positioned.
In one embodiment, the single-mode fiber 310-based cable trench temperature detection system further includes: a map display module 360. The map display module 360 is connected to the optical time domain reflection processing unit 343, and is configured to draw a virtual map of the cable to be tested according to the distribution information of the cable to be tested; and marking the position information on the virtual map, and displaying the marked virtual map.
Specifically, the map display module 360 may further draw a virtual map of the cable to be tested according to the distribution information of the cable to be tested. The virtual map may include information about the model of the cable to be tested, communication parameters, a laid line, an environment around the laid line (e.g., a building, a shop, etc.), and the like. When the temperature of the cable to be tested is abnormal, the processing module 340 may locate the temperature abnormal point and output the position information of the temperature abnormal point to the map display module 360, so as to mark the position information of the temperature abnormal point on the virtual map, and the map display module 360 may display the virtual map marked with the temperature abnormal point, so that the maintenance personnel can quickly find the temperature abnormal point on the virtual map.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features. It should be noted that "in one embodiment," "for example," "as another example," and the like, are intended to illustrate the application and are not intended to limit the application.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. The cable trench temperature monitoring method based on the single-mode optical fiber is applied to a cable trench temperature detection system, the cable trench temperature detection system comprises the single-mode optical fiber which is arranged in the same trench as a cable to be detected, and the method comprises the following steps:
coupling a laser signal of a preset power to the single-mode optical fiber to generate Raman scattered light in the single-mode optical fiber;
receiving the Raman scattered light, and demodulating and separating the received Raman scattered light to obtain anti-Stokes scattered light carrying temperature information;
acquiring temperature information distributed along the cable to be tested according to the laser signal and the anti-Stokes scattered light;
and when the temperature information of the cable to be detected is abnormal, outputting an alarm signal.
2. The method of claim 1, wherein before obtaining the temperature information of the cable under test according to the laser signal and the anti-stokes scattered light, the method further comprises:
demodulating and separating the received Raman scattered light to obtain Stokes scattered light;
eliminating random losses in the single mode fiber from the Stokes scattered light and the anti-Stokes light.
3. The method of claim 2, wherein said eliminating random losses in said single mode fiber from said stokes scattered light and anti-stokes light comprises:
acquiring the light intensity ratio of the anti-Stokes light to the Stokes scattered light;
and eliminating random loss in the single-mode optical fiber according to the light intensity ratio.
4. The method according to claim 1, wherein before outputting an alarm signal when the temperature information of the cable under test is abnormal, the method further comprises:
constructing a preset temperature correction model;
and correcting the temperature information of each temperature test point of the cable to be tested according to the preset temperature correction model.
5. The method of claim 4, wherein the constructing the preset temperature correction model comprises:
acquiring a plurality of calibration temperatures of the cable to be tested at different preset distances from the temperature test points to the cable to be tested based on a temperature sensor;
establishing a corresponding relation between the preset distance and the calibration temperature at each temperature test point;
and constructing a preset temperature correction model according to the corresponding relation between the preset distance and the calibration temperature corresponding to the plurality of temperature test points.
6. The method according to claim 1, wherein the outputting an alarm signal when the temperature information of the cable under test is abnormal comprises:
when any temperature information distributed along the cable to be tested is higher than a preset temperature, the temperature abnormal point of the cable to be tested is positioned and the alarm signal is output, and the alarm signal carries the position information of the temperature abnormal point of the cable to be tested.
7. The method of claim 6, further comprising:
drawing a virtual map of the cable to be tested according to the distribution information of the cable to be tested;
and displaying temperature information distributed along the cable to be tested on the virtual map.
8. The utility model provides a cable pit temperature detecting system based on single mode fiber for detect the temperature information of the cable that awaits measuring, the system includes:
the single-mode optical fiber is arranged in the same groove with the cable to be tested;
the light source module is coupled with the single-mode optical fiber and used for coupling a laser signal with preset power to the single-mode optical fiber so as to generate Raman scattering light in the single-mode optical fiber;
the optical detection module is coupled with the single-mode optical fiber and used for receiving the Raman scattering light, demodulating and separating the received Raman scattering light to obtain anti-Stokes scattering light carrying temperature information and realize photoelectric conversion;
the processing module is respectively connected with the light source module and the light detection module and used for acquiring temperature information distributed along the cable to be detected according to the laser signal and the anti-Stokes scattered light and outputting an alarm instruction when the temperature information of the cable to be detected is abnormal;
and the alarm module is connected with the processing module and used for receiving the alarm instruction and executing sound-light alarm operation according to the alarm instruction.
9. The system of claim 8, wherein the processing module comprises:
the conversion unit is connected with the optical detection module and used for receiving an electric signal and carrying out analog-to-digital conversion on the electric signal;
the processing unit is connected with the conversion unit and used for acquiring temperature information distributed along the cable to be tested according to the electric signal converted by the analog-digital conversion;
and the optical time domain reflection processing unit is connected with the light source module and the optical detection module and is used for positioning the temperature abnormal point of the cable to be detected so as to acquire the position information of the temperature abnormal point.
10. The system of claim 9, further comprising:
the map display module is connected with the optical time domain reflection processing unit and used for drawing a virtual map of the cable to be tested according to the distribution information of the cable to be tested; and marking the position information on the virtual map, and displaying the marked virtual map.
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