CN205785255U - A kind of railway monitoring system based on quasi-distributed optical fiber sensing network - Google Patents

Abstract

This example discloses a track monitoring system based on a quasi-distributed optical fiber sensor network. Its structure is that fiber Bragg gratings 2 are connected into a grating string through single-mode optical fiber 3, and multiple grating strings are cascaded to form a fiber grating sensor array 4. , stick on the track 1, controlled by optical switch 9; drive power source 5 drives broadband light source 6, connects with optical switch 9 through optical isolator 7 and optical coupler 8; 10 connection, the signal is output to the arrayed waveguide grating filter 11, processed by the photodetector 12, the analog-to-digital converter 13 and the digital signal processing unit 14, transmitted to the monitoring computer 15, and finally to the central monitoring station 16. The utility model adopts the fiber grating as the sensor device to form a quasi-distributed sensor network, which can measure multiple points simultaneously in a wide range, has the advantages of strong anti-electromagnetic interference, low transmission loss, good stability, etc., and can be accurate and convenient. The amount of track strain monitored.

Description

A track monitoring system based on quasi-distributed optical fiber sensor network

The technical field

The utility model relates to the field of rail traffic monitoring, in particular to a rail monitoring system based on a quasi-distributed optical fiber sensor network.

Background technique

At present, China's railway construction is ushering in an unprecedented development peak. Railway construction and daily operation and maintenance work also put forward higher requirements for railway scientific and technological workers: How to measure the strain of the rail during railway operation to prevent temperature changes from causing seamless lines The derailment coefficient increases; how to conduct real-time monitoring of roadbed diseases along the railway and the stability of the protective slope, etc. These are the key issues to be solved urgently in the reconstruction of existing lines and the operation of high-speed railways.

In the case of a huge traffic load, if the rail system can be monitored in real time and an early warning message is issued before a disaster occurs, the safety and reliability of the entire rail transit system can be improved. However, the track system is a linear distribution. As far as China is concerned, the total length of the railway is 100,000 kilometers. Traditional monitoring methods are mostly designed for point-shaped or limited-area systems, and the power lines and substations in the system are generated. Electromagnetic wave interference will also interfere with traditional electromagnetic sensors. Therefore, if you want to build a sensor system suitable for domestic rail transit, in addition to considering the deformation of the rail itself due to temperature, speed, and load effects, as well as the relative displacement of structures and foundations along the rail (bridges, roadbeds, etc.) In addition to long-distance distributed monitoring, the quality and stability of monitoring information must also be considered.

The rail transit monitoring system based on quasi-distributed fiber grating sensing is mainly used to monitor the surface strain of the rail. The fiber grating is used for sensing, which is an emerging sensor device with anti-electromagnetic interference, high precision and large measurement range. , small transmission loss and long effective service life. For areas with fog, rain and few people in rail transit, equipment maintenance is difficult, and external devices are vulnerable to damage and theft. It is more suitable to use advanced fiber grating sensing technology for long-term real-time monitoring of rail transit systems. Rail transit has the characteristics of linear distribution, long distance, and many measurement points. It adopts distributed optical fiber sensing technology, which has incomparable advantages compared with other sensing technologies. It can detect the temperature of different positions of optical fibers up to tens of kilometers. and changes in physical quantities such as strain.

The track monitoring system based on optical fiber sensing of the utility model still has some deficiencies in practical application, for example, the sensor packaging is weak and easily damaged, and the demodulation rate of the wavelength demodulation equipment is low. Therefore, it is necessary to refer to foreign advanced technical solutions combined with the actual needs of domestic engineering applications to make fiber grating sensors meet the requirements of faster speed, higher precision and longer distance for track monitoring.

Utility model content

The technical problem to be solved by the utility model is to overcome the defects of the prior art and provide a track monitoring system based on a quasi-distributed optical fiber sensor network, which uses an optical fiber grating as a sensor and adopts a distributed optical fiber sensor technology, which has the same characteristics as The incomparable advantages of other sensing systems, such as anti-electromagnetic interference, high precision, large measurement range, small transmission loss and long effective service life, can monitor the track system efficiently and conveniently, with excellent monitoring effect .

In order to solve the above problems, the utility model adopts the following technical solutions:

The track monitoring system based on the quasi-distributed optical fiber sensor network includes an optical fiber sensor module, a light source module, an optical multiplexing module, an optical wavelength demodulation module, a data acquisition and processing module, and a monitoring center; the optical fiber sensor module is used for multi-point measurement. Composed of fiber grating sensor arrays, the system is set to cascade multiple fiber gratings. According to the spectral range of the light source, each fiber grating is set to four grid areas, namely FBG1, FBG2, FBG3 and FBG4. The mutual interval can be based on distributed monitoring Depending on the requirements, the sensor network is packaged by adhesive fixing and fixed on the side of the track system to form a sensor network to meet the requirements for quasi-distributed measurement of the track; the light source module uses a wide-spectrum light source as a monitoring The light source of the system is driven by the driving power supply; the wide-spectrum light enters the optical multiplexing module through the optical isolator, and the optical multiplexing module of the system is connected by a coupler and an optical switch combining wavelength division multiplexing and space division multiplexing technologies; The strain of the track is converted into an optical sensing signal through the sensing optical fiber, and reflected back to the wavelength demodulation module through the multiplexing module. In order to ensure the high precision of sensing signal demodulation, the optical wavelength demodulation of this monitoring system is adopted Erbium-doped fiber amplifier, multi-channel arrayed waveguide grating and photodetector based on edge filter demodulation technology; through the wavelength demodulation module, the sensing signal is demodulated into an analog measured signal, and further passed through the analog-to-digital converter and data The processing unit calculates the variation of the reflected wavelength of the grating center and displays it on the monitoring computer. The monitoring computer is connected to the remote central monitoring station to realize real-time distributed monitoring of the track.

The track monitoring system based on the quasi-distributed optical fiber sensing network is used to realize the distributed and real-time monitoring of the track. The wide-spectrum light source is driven by the driving power, and the wavelength-scanning distributed optical fiber sensing technology is used to convert the wide-spectrum light source It is injected into the optical fiber, and fiber Bragg grating (FBG) is used as the sensor to measure the parameters by detecting the change of the output spectrum; this system connects the wide-spectrum light source to the optical isolator, and uses the driving power to drive the wide-spectrum light source to emit wide-spectrum light to the coupling The optical fiber sensor array of this system is cascaded using single-mode optical fiber, and then connected to the optical switch, and the optical switch is connected to the wavelength demodulation system through a coupler to form a combination of wavelength division multiplexing and space division multiplexing Optical multiplexing system; the sensing signal of this system is reflected to the erbium-doped fiber amplifier through the coupler, and the erbium-doped fiber amplifier is connected with the arrayed waveguide grating filter, and then connected with the photodetector to form a wavelength demodulation system; the photodetector of the system It is connected with the data acquisition and processing module, specifically, an analog-to-digital converter is connected after the photoelectric detector, and then the analog-to-digital converter is connected to the monitoring computer through the digital signal processing unit, and then the data is transmitted to the central monitoring station through wireless communication Perform unified monitoring and analysis.

The system design structure of the utility model is shown in Fig. 1 .

Preferably, the sensing network of this system adopts a fiber grating sensing array, which is glued and protected for sensing, which not only can realize multi-point distributed measurement, but also has the advantages of high precision and good stability.

Preferably, the wavelength demodulation system uses an arrayed waveguide grating filter to perform quasi-linear filtering on the sensing signal, the light emitted by the broadband light source enters the fiber grating sensing array through the fiber coupler, and the reflected sensing signal is coupled through the optical fiber again The sensor enters the arrayed waveguide grating, and the sensing signals of different wavelengths are divided by the arrayed waveguide grating, and are linearly filtered on each channel at the same time, and the filtered signal is directly detected by the photodetector. The demodulation system is based on light intensity detection , suitable for dynamic and static measurement, with good linear output.

Preferably, the optical multiplexing module adopts the technology of combining wavelength division multiplexing and space division multiplexing, uses an optical switch to connect three or more grating strings in parallel, and selects different channels to receive the reflected light through the optical switch. Sensing signals, this multiplexing technology can effectively solve the problem of the limitation of the bandwidth of the light source in the wavelength division multiplexing sensing of the fiber grating and the limitation of the energy of the light source in the time division multiplexing sensing, so that the multiplexing of the fiber grating has a greater Flexibility. In addition, the center wavelengths of the fiber gratings connected in parallel can be the same, which reduces the cost of making fiber gratings.

The packaging structure of the fiber grating of the utility model is shown in Fig. 2 .

Preferably, the fiber grating sensing array is composed of a plurality of sensing fibers connected in parallel. After polishing and cleaning, the sensing fibers are fixed to the monitoring point on the side of the track with 502 glue, and the fiber cloth is wrapped on the outside of the fiber with epoxy resin glue. Forming a protective layer, this adhesive fixing method is the most commonly used packaging method, which has the advantages of simplicity, flexibility, quickness, and wide application.

The digital signal processing unit working process software flow chart of the present utility model is as shown in Figure 3, comprises steps:

S1: Perform device initialization: including initialization of input and output ports, initialization settings of module receiving status and sending status, etc.

S2: pulse signal generation: use the pulse signal to drive the operation of the digital signal processing unit.

S3: Read the analog-to-digital conversion result: read the result of the analog-to-digital converter.

S4: Calculating the variation of the reflected wavelength of the grating center; by analyzing the results of the analog-to-digital conversion, calculate the center wavelength of the sensing signal, and further make a difference with the center wavelength of the fiber grating to obtain the variation.

S5: Detect whether the measurement is completed: if the detection is completed, the work of the digital signal processing unit is ended, and the processing result is transmitted to the monitoring computer; otherwise, the analog-to-digital conversion result is re-read.

Advantage and beneficial effect of the present utility model are:

(1) The utility model uses a fiber grating as a sensor, which is an emerging sensor device with the advantages of anti-electromagnetic interference, high precision, large measurement range, small transmission loss and long effective service life.

(2) The utility model adopts distributed optical fiber sensing technology, which has incomparable advantages compared with other sensing systems, such as anti-electromagnetic interference, high precision, large measurement range, small transmission loss and long effective service life. Efficient and convenient monitoring of the track system.

(3) The utility model adopts the optical multiplexing technology combining wavelength division multiplexing and space division multiplexing, and uses the optical switch to realize the selection of multiple sensing signals. This multiplexing technology can effectively solve the problem of fiber grating in wavelength division multiplexing The limitation of the bandwidth of the light source during sensing and the limitation of the energy of the light source during time-division multiplex sensing make the multiplexing of fiber gratings more flexible, and the central wavelength of the fiber gratings connected in parallel can be the same, reducing the production cost. The cost of fiber gratings.

(4) The utility model adopts arrayed waveguide grating filter as the core device of the demodulation system, which is based on light intensity detection, is suitable for dynamic and static measurement, and has better linear output.

(5) The utility model adopts the unified monitoring and management of the central monitoring station. In view of the foggy, rainy and few people areas in the rail transit, the maintenance of equipment is difficult. The central monitoring station can conveniently carry out long-term real-time monitoring of the rail transit system, and realize It realizes the intelligent processing of the monitoring of the strain variable at different positions of the track with a length of tens of kilometers.

Description of drawings

Fig. 1 is a schematic diagram of the system structure of the present utility model.

Fig. 2 is a package cross-sectional view of the sensing optical fiber in the present invention.

Fig. 3 is the working software flowchart of the digital signal processing unit in the utility model.

In the figure: 1. track; 2. fiber Bragg grating; 3. single-mode fiber; 4. fiber grating sensor array; 5. driving power; 6. wide-spectrum light source; 7. optical isolator; 8. optical coupler; 9 1. Optical switch; 10. Erbium-doped fiber amplifier; 11. Arrayed waveguide grating filter; 12. Photodetector; 13. Analog-to-digital converter; 14. Digital signal processing unit; 15. Monitoring computer; 16. Central monitoring station ; 17, optical fiber cladding; 18, fiber cloth; 19, epoxy resin glue; 20, 502 glue.

detailed description

A kind of track monitoring system based on quasi-distributed optical fiber sensor network, embodiment 1

As shown in Figures 1 and 2, the utility model is a track monitoring system based on a quasi-distributed optical fiber sensor network. Fiber Bragg gratings 2 are connected to form grating strings through single-mode optical fibers 3, and multiple grating strings are cascaded to form optical fibers. The grating sensor array 4, and the fiber grating sensor array 4 is glued to the track 1, the single-mode optical fiber 1 connects the fiber grating sensor array 4 with the optical switch 9; the driving power supply 5 is connected to the broadband light source 6, and the broadband light source 6 is connected to the optical switch 9 Optical isolator 7 is connected, and optical isolator 7 is followed by optical coupler 8, and is connected on the optical switcher 9; Optical coupler 8 is connected with erbium-doped fiber amplifier 10 by reflection circuit, and erbium-doped fiber amplifier 10 is connected to array The waveguide grating filter 11 is connected with the photodetector 12 through the output channel; the photodetector 12 is followed by an analog-to-digital converter 13 and connected to a digital signal processing unit 14, and then the processed data is communicated wirelessly by a monitoring computer 15 transmission to the central monitoring station; the sensing optical fiber 4 is covered with an optical fiber cladding 17, fixed on the track 1 by 502 glue 20, and the fiber cloth 18 is glued to the outside of the optical fiber sensing 4 with epoxy glue 19.

In the track detection system composed of the optical fiber sensor network, the wide-spectrum light source is driven by the driving power supply, and emits wide-spectrum light to the optical isolator, and the high-isolation degree of the optical isolator is used to realize the high-efficiency transmission of wide-spectrum light; Optical isolator, wide-spectrum light enters the coupler connected with the optical isolator, and then transmits the wide-spectrum light to the fiber grating sensing array in the adhesive package, the optical fiber sensing array is connected to the optical multiplexing module, and the strained track drive The optical fiber sensor sends out the sensing signal, and the optical sensing signal is reflected to the wavelength demodulation module through the optical multiplexing module. The sensing signal is transmitted to the analog-to-digital converter through wavelength demodulation, and then enters the digital signal processing unit for digital signal processing, and transmits the processing result to the monitoring computer, and then enters the central monitoring station through wireless communication for unified analysis and monitoring. deal with.

The optical fiber sensing module, optical multiplexing module and optical demodulation module used in the utility model are all existing mature technologies. The wide-spectrum light source, optical isolator, optical coupler, photoelectric detector, erbium-doped fiber amplifier, etc. The hardware is existing mature technology, which is not described in the utility model; the software workflow of the digital signal processing unit adopted in the utility model is as shown in Figure 3, but this software part is not as the scope of protection of the utility model.

Finally, it should be noted that obviously, the above-mentioned embodiments are only examples for clearly illustrating the utility model, rather than limiting the implementation manner. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And the obvious changes or changes derived therefrom are still within the protection scope of the present utility model.

Claims (6)

1. a railway monitoring system based on quasi-distributed optical fiber sensing network, it is characterised in that described system includes optical fiber Sensor assembly, light source module, light Multiplexing module, wavelength demodulation module, digital sampling and processing and Surveillance center；Wherein Fibre Optical Sensor module is made up of the Fiber Bragg Grating Sensor Array for multimetering, and native system is set to multifiber light Grid cascade, and often will be set to four grid regions with fiber grating according to light source light spectrum scope, FBG1, FBG2, FBG3 and FBG4 respectively, Spaced can according to distributed monitoring require depending on, then use gluing fixed method that sensing network is sealed Dress, is fixed on the side of rail system, and then forms a sensor network, it is achieved the requirement of measurement quasi-distributed to track； Light source module uses wide spectrum light source as the light source of monitoring system, is driven by driving power supply；Wide spectrum optical is entered by optoisolator Entering light Multiplexing module, the light Multiplexing module of system uses the photoswitch that bonder combines with wavelength-division multiplex and space division multiplexing technology Device is connected；The dependent variable of track is changed to light transducing signal by sensor fibre dress, and is reflected back wavelength solution by Multiplexing module Mode transfer block, the wavelength demodulation of this monitoring system, is to use erbium-doped fiber amplifier, manifold based on edge filter demodulation demodulation techniques Channel array waveguide optical grating and photodetector complete；By Wavelength demodulation module, transducing signal is demodulated into the tested letter of simulation Number, further by analog-digital converter and data processing unit, calculate raster center reflection wavelength variable quantity, and show at prison On control computer, monitoring computer is connected with remote central monitoring station, it is achieved the real-time distributed monitoring to track.

2. by the railway monitoring system based on quasi-distributed optical fiber sensing network described in claim 1, it is characterised in that use Length scanning type Distributed Optical Fiber Sensing Techniques, in wide spectrum light source injection fibre, using Fiber Bragg Grating FBG (FBG) as passing Sensor, carries out parameter measurement by the change of detection output spectrum.

3. railway monitoring system based on quasi-distributed optical fiber sensing network as claimed in claim 1, it is characterised in that by width Spectrum light source is connected on optoisolator, utilizes and drives power drives wide spectrum light source to launch wide spectrum optical to bonder.

4. railway monitoring system based on quasi-distributed optical fiber sensing network as claimed in claim 1, it is characterised in that optical fiber Sensor array utilizes single-mode fiber to cascade, and is then attached on light switch, and photoswitch is again by bonder and wavelength solution Adjusting system is connected, the optical multiplexing system that formation wavelength-division multiplex and space division multiplexing combine.

5. railway monitoring system based on quasi-distributed optical fiber sensing network as claimed in claim 1, it is characterised in that sensing Signal is by coupler reflectivity to erbium-doped fiber amplifier, and erbium-doped fiber amplifier is connected with array waveguide grating wave filter, Then it is connected with photodetector, forms Wavelength demodulation system.

6. railway monitoring system based on quasi-distributed optical fiber sensing network as claimed in claim 1, it is characterised in that photoelectricity Detector and data acquisition processing module is connected, specifically, photodetector is followed by an analog-digital converter, is then turned by modulus Parallel operation is connected to monitor on computer by digital signal processing unit, then by radio communication, transfers data to center prison Control station carries out unifying monitoring and analyzes.