CN203811294U - Fiber-Raman cable-temperature monitoring and alarm system with attenuation self-compensating function - Google Patents

Abstract

The utility model discloses a fiber-Raman cable-temperature monitoring and alarm system with an attenuation self-compensating function, and the system comprises a fiber pulse laser, a fiber wavelength division multiplexer, a first photoelectric receiving module, a second photoelectric receiving module, a data collection module, a computer, a calibration optical cable, a sensing optical cable, a reflector, and a point-mode temperature sensor. Computer software comprises a temperature real-time monitoring part, a history data storage part, and a temperature rise fault alarm part. A fiber-Raman distributed temperature sensor with the attenuation self-compensating function can eliminate the node loss caused by bending and strain of a cable, especially eliminates the impact of optical fiber attenuation change caused by long-time working and working environment difference, achieves the attenuation self-compensating function, and improves the stability and reliability in measuring the temperature of the system. The computer software for cable temperature monitoring and alarm can obtain the working state of the cable through the comparison of the current data with the history data, thereby achieving the early-warning and alarm functions.

Description

The self-compensating fiber Raman cable temperature monitoring of a kind of decay and warning system

Technical field

The utility model belongs to distributing optical fiber sensing thermometric field, the particularly self-compensating fiber Raman cable temperature monitoring of a kind of decay and warning system, and it is the system of monitoring power cable Temperature Distribution and abnormal alarm.

Background technology

Along with the development of intelligent grid, the working state monitoring of cable has been proposed to more and more higher requirement at present.Traditional temperature sensor is due to the characteristic of its point type thermometric, to the very large inconvenience of installing and networking brings.Temperature-sensing system based on fiber raman scattering is a kind of distributed temperature sensing system truly, optical fiber both can transmitting optical signal, it itself is also sensor, so its thermometric monitoring range is large, add the feature that it is not subject to electromagnetic interference (EMI), make it be easy to install and networking, greatly reduce the cost of obtaining information.

When cable is laid sensing optic cable along the line, generally there are two kinds of methods available.First method is optimal mounting means, directly by optical fiber built-in on cable conductor core (or insulation shielding interlayer), the temperature of optical fiber is the temperature of cable like this, the information of the cable duty obtaining is comparatively accurate, but this has also brought two problems: 1 needs special cable, it is more inconvenient that the installation of 2 this special cables connects, so this scheme is not promoted at present.Second method is actual mounting means, be about to the outside surface that optical fiber is arranged on cable, this mode is installed more convenient, but also there are two problems, although the temperature of cable fibre core is very high while breaking down on the one hand, the temperature of cable surface is lower, average temperature rising is 10 degrees Celsius of left and right, but the difference due to cable laying position, and the temperature of cable surface is subject to extraneous environmental impact larger, the cable temperature of different location different time is poor just 10 degrees Celsius, so the warning of temperature need to be for the temperature rise situation of diverse location and determined; On the other hand, optical fiber is in different environment (as temperature and humidity) over time for a long time, the difference that will cause the attenuation coefficient of each section of optical fiber, and this impact of accurate calibration on temperature value is larger, so in such system, thermometric noise level is not special distinct issues, and eliminate the impact of optical fiber attenuation change along the line on temperature calibration, thereby the precision that improves temperature calibration, seems and is even more important.

Stability, reliability and low cost are the basic demands of technology in electric system, this patent, for the feature of power cable thermometric, has proposed a kind of self-compensating fiber Raman cable temperature monitoring of decay and warning system that is suitable for short-distance and medium-distance application.

Summary of the invention

Problem to be solved in the utility model is: for the demand of power cable distributed temperature measuring, design a kind of energy long-term stability, reliability service and lower-cost, be applicable to the self-compensating fiber Raman cable temperature monitoring of decay and the warning system of short-distance and medium-distance application.

The technical scheme in the invention for solving the above technical problem is:

Decay self-compensating fiber Raman cable temperature monitoring and warning system, comprise fiber pulse laser, optical fibre wavelength division multiplexer, the first photoelectricity receiver module, the second photoelectricity receiver module, data acquisition module, computing machine, demarcation optical cable, sensing optic cable, reflective mirror and point temperature sensor.

Optical fibre wavelength division multiplexer has 4 ports, wherein 1550nm input port A is connected with fiber pulse laser, output port B is connected with demarcation any one end of optical cable, 1450nm output port C is connected with the input end of the first photoelectricity receiver module, and 1663nm output port D is connected with the input end of the second photoelectricity receiver module; The output terminal of the first photoelectricity receiver module and the second photoelectricity receiver module is connected with two input ends of data acquisition module, and the trigger pip of data acquisition module is produced by fiber pulse laser, and the output terminal of data acquisition module is connected with computing machine; Demarcate the remaining port of optical cable and any one end of sensing optic cable and be connected, the sensing optic cable other end is connected with reflective mirror; Point temperature sensor is connected with computing machine.

The centre wavelength of described fiber pulse laser is 1550nm, and spectrum three dB bandwidth is 0.3nm, and laser pulse width is 15ns, and peak power 0～100W is adjustable, repetition frequency 0.5～20kHz.

The bandwidth of described optical fibre wavelength division multiplexer is 7nm.

The first described photoelectricity receiver module and the second photoelectricity receiver module convert anti-Stokes light and stokes light electric signal to and amplify respectively, its voltage range is mated with the input voltage range of data acquisition module, what photoelectricity receiver module adopted is APD detection circuit, and its three dB bandwidth is 80MHz.

The sampling rate of described data acquisition module is 100MHz.

Described demarcation optical cable and sensing optic cable are the graded index multimode fibers of identical 62.5-125um, and demarcation cable length is 220m, comprises 200m blind area, and sensing optic cable is arranged on cable surface.

Described reflective mirror should reach 99% for 1550nm, 1450nm and 1663nm reflection of light rate.

Described point temperature sensor is connected with computing machine, for feeding back the temperature information of demarcating optical cable.

Computer software comprises three parts: temperature Real-Time Monitoring part, and storage of history data P part and temperature rise fault alarm part, temperature Real-Time Monitoring is the state of temperature for showing that cable is current partly; Storage of history data P is partly for preserving the data of cable duty, conveniently consults cable work historic state and provides data basis for temperature rise fault alarm; Rise fault alarm partly by more current state of temperature and historical data, analyze the position that may will break down, and indicate the position of having broken down.

The utility model advantage is compared to the prior art:

1), the utility model can eliminate cable along the line because of bending, strain, node loss, particularly works long hours and impact that optical fiber attenuation that the factor such as working environment difference causes changes.Realize the self compensation of decay, improve the Stability and dependability of system thermometric.And the selection of sensing optic cable is not had to special requirement, even can select the optical cable that lays in advance, easy for installation.Be specially adapted to monitoring and the warning of medium or short range power cable temperature along the line.

2), the temperature rise fault alarm that the utility model proposes can monitoring cable diverse location place temperature rise situation, thereby can carry out temperature alarming for the temperature rise situation of diverse location.

Accompanying drawing explanation

Fig. 1 is the structured flowchart of the utility model system;

Fig. 2 is in the sensing optic cable with catoptron, and the propagation condition of pulse laser and scattered light is schematic diagram;

Fig. 3 is the schematic diagram of cable temperature monitoring and warning system software configuration.

Embodiment

Below in conjunction with accompanying drawing, the utility model system is elaborated.

As shown in Figure 1, decay self-compensating fiber Raman cable temperature monitoring and warning system, consist of the following components: fiber pulse laser 1, optical fibre wavelength division multiplexer 2, the first photoelectricity receiver module 3, the second photoelectricity receiver module 4, data acquisition module 5, computing machine 6, demarcate optical cable 7, sensing optic cable 8, reflective mirror 9 and point temperature sensor 10.

The centre wavelength of fiber pulse laser 1 is 1550nm, and spectral width is 0.3nm, and laser pulse width is 15ns, and peak power 0～100W is adjustable, repetition frequency 0.5～20kHz.The bandwidth of optical fibre wavelength division multiplexer 2 is 7nm.The first photoelectricity receiver module 3 and the second photoelectricity receiver module 4 convert anti-Stokes light and stokes light electric signal to and amplify respectively, its voltage range is mated with the input voltage range of data acquisition module 5, what photoelectricity receiver module adopted is APD detection circuit, and three dB bandwidth is 80MHz.The sampling rate of data acquisition module 5 is 100MHz.The graded index multimode fiber of demarcating optical cable 7 and sensing optic cable 8 and be identical 62.5/125um, demarcating optical cable 7 length is that 220m(comprises 200m blind area), sensing optic cable 8 is laid on cable surface.Reflective mirror 9 should reach 99% for 1550nm, 1450nm and 1663nm reflection of light rate.Point temperature sensor 10 is connected with computing machine 6, for feedback temperature groove temperature information.

In sensing optic cable with catoptron, the propagation condition of pulse laser 11 and Raman backscatter light 12 as shown in Figure 2.At the same position of optical fiber, have Raman scattering process dorsad twice, be once the dorsad Raman scattering of laser pulse in propagated forward process, another time be laser pulse after mirror-reflection, the Raman scattering dorsad in back-propagating process.The propagation distance of the back-scattering light that this double scattering process produces in optical fiber is different, through different time, arrives photoelectricity receiver module.

As shown in Figure 3, cable temperature monitoring and warning system software, consist of three parts: temperature Real-Time Monitoring part 13, storage of history data P part 14 and temperature rise fault alarm part 15.Temperature Real-Time Monitoring part 13 completes and comprises the demodulation of the obtaining of light intensity data, temperature and the function that shows the state of temperature that cable is current; Storage of history data P part 14 is regularly preserved cable temperature information, conveniently consults cable work historic state and provides data basis for temperature rise fault alarm; Temperature rise fault alarm part 15, by more current state of temperature and historical data, analyzes the position that may will break down, and indicates the position of having broken down.

The utility model can be realized the self compensation of decay, based on following principle, realizes:

As shown in Figure 2, the total length of demarcating optical cable 7 and sensing optic cable 8 is L, and the position that scattering occurs is l, and temperature is T, and establishing so light intensity is I ₀dorsad Raman scattering light intensity (the stokes light I of laser pulse in propagated forward process _s1, anti-Stokes I _as1) can be expressed as:

$I_{s1}=I_0{\mathrm{\Γ}}_s\left(l\right)v_s^4{R}_s\left(T\right)\exp (-{\∫}_0^l{\mathrm{\α}}_0\left(z\right)\mathrm{dz}-{\∫}_0^l{\mathrm{\α}}_s\left(z\right)\mathrm{dz})---\left(1\right)$

$I_{\mathrm{asl}}=I_0{\mathrm{\Γ}}_{\mathrm{as}}\left(l\right)v_{\mathrm{as}}^4{R}_{\mathrm{as}}\left(T\right)\exp (-{\∫}_0^l{\mathrm{\α}}_0\left(z\right)\mathrm{dz}-{\∫}_0^l{\mathrm{\α}}_{\mathrm{as}}\left(z\right)\mathrm{dz})---\left(2\right)$

Wherein, Γ _sand Γ (l) _as(l) be respectively the scattering capture rate of position l place stokes light and anti-Stokes light, ν _sand ν _asbe respectively the spectral frequency of stokes light and anti-Stokes light, α _o(z), α _sand α (z) _as(z) be respectively z position incident pulse laser, the light wave transmissions total attenuation coefficient of stokes light and anti-Stokes light, R _sand R (T) _as(T) be respectively the scattered light intensity ratio of stokes light and anti-Stokes light:

R _s(T)＝[1-exp(-hΔν/kT)] ^-1 （3）

R _as(T)＝[exp(hΔν/kT)-1] ^-1 （4）

Wherein h is Planck constant, and k is Boltzmann constant, and Δ ν is Raman frequency shift amount.

In like manner, laser pulse is after mirror-reflection, and in same position, scattering, (the stokes light I of the Raman scattering light intensity dorsad in back-propagating process occur at l place _s2, anti-Stokes I _as2) can be expressed as:

$I_{s2}=I_0{\mathrm{\Γ}}_s\left(l\right)v_s^4{R}_s\left(T\right)R_0{R}_{\mathrm{ss}}\exp (-{\∫}_0^L{\mathrm{\α}}_0\left(z\right)\mathrm{dz}-{\∫}_l^L{\mathrm{\α}}_0\left(z\right)\mathrm{dz}-{\∫}_0^L{\mathrm{\α}}_s\left(z\right)\mathrm{dz}-{\∫}_l^L{\mathrm{\α}}_s\left(z\right)\mathrm{dz})---\left(5\right)$

$I_{\mathrm{as}2}=I_0{\mathrm{\Γ}}_{\mathrm{as}}\left(l\right)v_{\mathrm{as}}^4{R}_{\mathrm{as}}\left(T\right)R_0{R}_{\mathrm{ass}}\exp (-{\∫}_0^L{\mathrm{\α}}_0\left(z\right)\mathrm{dz}-{\∫}_l^L{\mathrm{\α}}_0\left(z\right)\mathrm{dz}-{\∫}_0^L{\mathrm{\α}}_{\mathrm{as}}\left(z\right)\mathrm{dz}-{\∫}_l^L{\mathrm{\α}}_{\mathrm{as}}\left(z\right)\mathrm{dz})---\left(6\right)$

R wherein ₀, R _ssand R _assbe respectively incident laser pulse, stokes light and anti-Stokes light are at the reflectivity at minute surface place.

Get respectively I _s1with I _s2, I _as1with I _as2geometrical mean can obtain:

$I_s=\sqrt{I_{s1}{I}_{s2}}=I_0{\mathrm{\Γ}}_s\left(l\right)v_s^4{R}_s\left(T\right)\sqrt{R_0{R}_{\mathrm{ss}}}\exp (-{\∫}_0^L{\mathrm{\α}}_0\left(z\right)\mathrm{dz}-{\∫}_0^L{\mathrm{\α}}_s\left(z\right)\mathrm{dz})---\left(7\right)$

$I_{\mathrm{as}}=\sqrt{I_{\mathrm{as}1}{I}_{\mathrm{as}2}}=I_0{\mathrm{\Γ}}_{\mathrm{as}}\left(l\right)v_{\mathrm{as}}^4{R}_{\mathrm{as}}\left(T\right)\sqrt{R_0{R}_{\mathrm{ass}}}\exp (-{\∫}_0^L{\mathrm{\α}}_0\left(z\right)\mathrm{dz}-{\∫}_0^L{\mathrm{\α}}_{\mathrm{as}}\left(z\right)\mathrm{dz})---\left(8\right)$

By two formula above, can be found out, relevant to decay does not change with the variation of position l, and anti-Stokes light and stokes light beam intensity ratio are so:

$\frac{I_{\mathrm{as}}}{I_s}=Q\frac{R_{\mathrm{as}}\left(T\right)}{R_s\left(T\right)}---\left(9\right)$

Wherein Q is constant, can be obtained again by (3), (4) two formulas:

$\frac{R_{\mathrm{as}}\left(T\right)}{R_s\left(T\right)}=\exp (-\mathrm{h\Δv}/\mathrm{kT})---\left(10\right)$

Position can be definite by the time delay of scattered light, and temperature can be calculated by following formula:

$T=\frac{\mathrm{h\Δv}/k}{\ln (I_s/I_{\mathrm{as}})+\ln Q}---\left(11\right)$

H Δ ν/k and lnQ are constant, if by the data of calibration zone optical fiber, determine in real time h Δ ν/k and these two parameters of lnQ, just can eliminate and work long hours and impact that optical fiber attenuation that the factor such as working environment difference causes changes, realize the self compensation decaying.

The utility model can be realized monitoring and the warning of temperature rise situation, is to use following algorithm to realize:

Step1: the cable Temperature Distribution situation along the line data when searching out cable normally working from historical data, are designated as T ₀(z).

Step2: partly obtain current cable Temperature Distribution situation data along the line from temperature Real-Time Monitoring, be designated as T (z).

Step3: temperature rise situation Tr (z)=T (the z)-T that calculates cable each point along the line place ₀(z).

Step4: calculate cable maximum temperature rise value along the line wherein N is that z counts from the total thermometric in 0 to L scope.

Step5: if Tr _maxsurpass a certain default alarm threshold value, produce temperature rise and report to the police; Otherwise, return to Step2.

The not detailed disclosed part of the utility model belongs to the known technology of this area.

Although above the illustrative embodiment of the utility model is described; so that the technician of this technology neck understands the utility model; but should be clear; the utility model is not limited to the scope of embodiment; to those skilled in the art; as long as various variations appended claim limit and the spirit and scope of the present utility model determined in, these variations are apparent, all innovation and creation that utilize the utility model design are all at the row of protection.

Claims (8)

1. a decay self-compensating fiber Raman cable temperature monitoring and warning system, it is characterized in that, comprise fiber pulse laser (1), optical fibre wavelength division multiplexer (2), the first photoelectricity receiver module (3), the second photoelectricity receiver module (4), data acquisition module (5), computing machine (6), demarcate optical cable (7), sensing optic cable (8), reflective mirror (9) and point temperature sensor (10); Optical fibre wavelength division multiplexer (2) has 4 ports, wherein 1550nm input port A is connected with fiber pulse laser (1), output port B is connected one end arbitrarily with demarcation optical cable (7), 1450nm output port C is connected with the input end of the first photoelectricity receiver module (3), and 1663nm output port D is connected with the input end of the second photoelectricity receiver module (4); The output terminal of the first photoelectricity receiver module (3) and the second photoelectricity receiver module (4) is connected with two input ends of data acquisition module (5), the trigger pip of data acquisition module (5) is produced by fiber pulse laser (1), and the output terminal of data acquisition module (5) is connected with computing machine (6); The remaining port of demarcating optical cable (7) is connected with any one end of sensing optic cable (8), and sensing optic cable (8) other end is connected with reflective mirror (9); Point temperature sensor (10) is connected with computing machine (6).

2. the self-compensating fiber Raman cable temperature monitoring of decay as claimed in claim 1 and warning system, the centre wavelength that it is characterized in that fiber pulse laser (1) is 1550nm, spectrum three dB bandwidth is 0.3nm, laser pulse width is 15ns, peak power 0～100W is adjustable, repetition frequency 0.5～20kHz.

3. the self-compensating fiber Raman cable temperature monitoring of decay as claimed in claim 1 and warning system, the bandwidth that it is characterized in that optical fibre wavelength division multiplexer (2) is 7nm.

4. the self-compensating fiber Raman cable temperature monitoring of decay as claimed in claim 1 and warning system, it is characterized in that the first photoelectricity receiver module (3) and the second photoelectricity receiver module (4) convert anti-Stokes light and stokes light electric signal to and amplify respectively, its voltage range is mated with the input voltage range of data acquisition module (5), what photoelectricity receiver module adopted is APD detection circuit, and its three dB bandwidth is 80MHz.

5. the self-compensating fiber Raman cable temperature monitoring of decay as claimed in claim 1 and warning system, the sampling rate that it is characterized in that data acquisition module (5) is 100MHz.

6. the self-compensating fiber Raman cable temperature monitoring of decay as claimed in claim 1 and warning system, it is characterized in that demarcating optical cable (7) and sensing optic cable (8) and be the graded index multimode fiber of identical 62.5-125um, demarcating optical cable (7) length is 220m, comprise 200m blind area, sensing optic cable (8) is arranged on cable surface.

7. the self-compensating fiber Raman cable temperature monitoring of decay as claimed in claim 1 and warning system, is characterized in that reflective mirror (9) should reach 99% for 1550nm, 1450nm and 1663nm reflection of light rate.

8. the self-compensating fiber Raman cable temperature monitoring of decay as claimed in claim 1 and warning system, is characterized in that point temperature sensor (10) is connected with computing machine (6), for feeding back the temperature information of demarcating optical cable (7).