Based on narrow band laser demodulating fiber bragg grating temp measuring system
Technical field
The utility model belongs to technical field of temperature measurement.
Background technology
As the power equipment portion such as power cable in urban distribution network, transformer is increasing, electric power facility load
Voltage and current also improve constantly, this will necessarily increase temperature during power equipment operation, even more than limiting temperature, easily
The failures such as equipment short circuit, open circuit, or even blast is caused to trigger fire disaster accident.Therefore, how the temperature of power system is existed
Line monitors, and it is very important that the very first time, which finds and removed a hidden danger,.
At present, most domestic power equipment is all based on the temp measuring system of conventional telecommunications sensor, and traditional electricity
Sensor is highly prone to electromagnetic interference, and many local environment very severes, and it is good that this requires that temperature survey facility has
Insulation characterisitic, have very high antijamming capability, detection range are big, service life is long, it is not charged, do not done by the electromagnetism of power equipment
Disturb, it is flexible for installation and conveniently, cost it is low, and can pass through multiplexing technology carry out distributed networking carry out temperature survey.
Utilize the various temp measuring systems designed by the sensitivity characteristic of fiber grating pair temperature, its fiber grating signal demodulation skill
Art is the key in optical fiber grating temperature-measuring field, and it is exactly to lead to the change for monitoring wavelength of optical signal so as to which indirect gain is tested to demodulate
Temperature signal.At present, the demodulation techniques of optical fiber grating temperature-measuring have many kinds:(1)Spectrometer monitoring method, grating is transmitted back to
Optical signal access spectrometer by spectrum so that obtain information measured, but its demodulation resolution ratio is not high, expensive and not portable
Band;(2)Tunable F-P interferometer wave filter demodulation method, by controlling PZT magnitude of voltage to control the optical wavelength of F-P cavity, work as raster center
When wavelength is identical with the wavelength that F-P cavity transmits, now magnitude of voltage corresponding to PZT is the centre wavelength of fiber grating, but high-precision
The F-P cavity wave filter of degree is expensive and filtering loss is larger;(3)Matched fiber grating demodulation method, the light of wideband light source is sent
Enter sensing grating, then by a matched FBG as sensing grating parameter, when the spectrum of the two overlaps, matching it is anti-
It is most strong to penetrate light;But if the wavelength of sensing grating because extraneous factor is drifted about, its spectrum intersection will very little, matching
The reflective light intensity of grating will very little, nonlinearity erron is larger, is not easy to demodulate.
Utility model content
In order to solve the above problems, the utility model provides one kind and is based on narrow band laser demodulating fiber bragg grating thermometric system
System.Distributed Feedback Laser is used as restitution element again as light source, simplifies optical fiber grating temperature-measuring system structure.Optical fiber grating sensing
Device compared to traditional temperature sensor, its service life is long, precision is high, not by electromagnetic interference, detection range is big, is easy to tie up
Protect and use is safer.
The utility model adopts the following technical scheme that realization:One kind is based on narrow band laser demodulating fiber bragg grating thermometric system
System, including STM32 master control borads(8), Distributed Feedback Laser(2), drive module(1), temperature control modules(5), coupler(3)、FBG
Fiber-optic grating sensor(4), photoelectric conversion amplifier(6), data acquisition unit(7), the Distributed Feedback Laser and temperature control modules
Connected with drive module, the other end of the laser is connected with coupler input, an output end of the coupler with
Grating sensor connects, and another output end of the coupler is connected to the input of photoelectric conversion amplifier, the photoelectricity
Switching amplifier is connected with data acquisition unit, and the data acquisition unit connects master control borad.Using fiber grating for the quick of temperature
Perception, using distributed Feedback Distributed Feedback Laser as light source, by sending ripple under the co- controlling of drive module and thermal module
Long tunable laser, laser of narrowband are incided on FBG fiber gratings by coupler, meet that the light of Bragg condition is reflected back toward
Coupler enters photoelectric conversion amplifier, and optical signal is converted into electric signal, and filtered, amplification is exported to data acquisition unit,
Signal transacting is carried out to the data gathered, obtains tested temperature information.
The coupler is three-dB coupler.
The fiber grating demodulation method is tunable narrowband optical source demodulation method, makes it by the wavelength for changing narrow-band light source
Periodic raster, the centre wavelength of fiber-optic grating sensor is correspond at largest light intensity.
The centre wavelength scope 1549.5+0.2nm of the FBG fiber gratings.
The narrow-band light source is made up of drive module, temperature control modules and Distributed Feedback Laser.
The Distributed Feedback Laser is encapsulated using 14 pin butterflies, centre wavelength 1550.00+0.4nm(25℃)。
The drive module uses LM317 integrated circuits.
The temperature control modules use the DC388B temperature controllers provided by linear companies.
The beneficial effects of the utility model:(1)Distributed Feedback Laser has low-loss, narrow compared with general semiconductor laser
The advantages that line width, high stability and tunable wave length;(2)Fiber-optic grating sensor by electromagnetic field due to its passivity, do not done
Disturb, high-temp resisting high-humidity resisting, not by chemical attack, insertion loss is low, performance long-time stability are good the features such as, be particularly suitable for it is inflammable,
Used under the adverse circumstances such as explosive and strong electromagnetic, can be very good to apply in power equipment temperature survey;(3)Temperature signal passes through
Optical signal transmission, stable and reliable for performance, measurement accuracy and high resolution, temperature measurement accuracy can reach 0.1 DEG C;(4)Arrowband
Light source scanning method has great signal to noise ratio and higher resolution ratio;(5)Can be by multiplexing technology by multiple temperature sensor strings
Knot, to realize distributed temperature measuring network.
Brief description of the drawings
Fig. 1 is schematic diagram of the present utility model;
In figure:1- drive modules, 2-DFB lasers, 3- couplers, 4-FBG fiber-optic grating sensors, 5- temperature control moulds
Block, 6- photoelectric conversion amplifiers, 7- data acquisition units, 8-STM32 master control borads.
Embodiment
The utility model is further described with reference to the accompanying drawings and detailed description.
As shown in figure 1, a kind of be based on narrow band laser demodulating fiber bragg grating temp measuring system, mainly include STM32 master control borads
(8), Distributed Feedback Laser(2), drive module(1), temperature control modules(5), coupler(3), FBG fiber-optic grating sensors(4)、
Photoelectric conversion amplifier(6), data acquisition unit(7);The Distributed Feedback Laser is connected with temperature control modules and drive module, institute
The other end for stating Distributed Feedback Laser is connected with coupler input, and the other end of the coupler is connected with grating sensor, described
The output end of coupler is connected to the input of photoelectric conversion amplifier, the photoelectric conversion amplifier and data acquisition unit phase
Even, the data acquisition unit connects master control borad;The coupler is three-dB coupler;The narrow-band light source is by drive module, temperature
Control module and Distributed Feedback Laser composition;The drive module uses LM317 integrated circuits;The temperature control modules use by
The DC388B temperature controllers that linear companies provide;The Distributed Feedback Laser is encapsulated using 14 pin butterflies, centre wavelength
1550.00+0.4nm(25℃);The centre wavelength scope 1549.5 of FBG fiber gratings+0.2nm。
The system architecture is divided into following three parts, fiber-optic grating sensor part, Distributed Feedback Laser demodulation part and
STM32 master control systems part.Laser sends tunable wave length laser, arrowband in the presence of drive circuit and temperature controller
Laser is incided on FBG fiber gratings by coupler, and FBG gratings are substantially an optical filters, meet Bradley glazing bar
The incident light of part is reflected through coupler and entered in photoelectric conversion amplifier, and photoelectric conversion amplifier converts optical signals to electricity
Signal, into STM32 master control borads, while triangular wave caused by master control borad carries out digital quantity to the reference voltage of temperature controller
Regulation, control laser is scanned to FBG gratings, and performs peak-seeking algorithm, obtains and temperature corresponding FBG centers in real time
Wavelength, when capturing the peak value of FBG centre wavelengths, gather centre wavelength and carry out data operation, can thus complete whole
The test of individual system and the monitoring of temperature.
Distributed Feedback Laser demodulation part, the system use light source portion of the distributed feedback narrow band laser as whole system
Point, the maximum advantage of distributed feedback laser is that monochromaticjty is very good, that is, its spectrum is very pure, and with compared with
High side mode suppression ratio, what is applied within the system is that centre wavelength is 1550.17nm(Under the conditions of test temperature is 28 oC)
DFB narrow band lasers, output current is very good in 80mA, performance.The constant current that driving circuit section is formed using LM317 is driven
It is dynamic, while protection circuit is designed with to prevent output voltage to be more than 2v, avoid peak current or peak voltage from producing laser
Raw damage.
Fiber-optic grating sensor part, the sensitiveness using FBG for temperature, the change information of temperature can be modulated to
Among the change of FBG optic fiber grating wavelength information;The reference voltage provided due to Distributed Feedback Laser tunable wave length, drive circuit
Corresponded with Distributed Feedback Laser wavelength, using the linear relationship between FBG fiber bragg grating center wavelengths and temperature, by seeking
Peak algorithm determines the centre wavelength of the Distributed Feedback Laser i.e. now centre wavelength of FBG fiber gratings, passes through FBG centre wavelengths and temperature
The linear relationship of degree can obtain current temperature information.
STM32 master control systems part, 1V ~ 2V triangular wave is produced using its hardware circuit and algorithm, so as to laser
Temperature control circuit carries out the regulation of digital quantity, produces periodic light wave and FBG gratings are scanned;And amplified by gathering photoelectricity
The output signal of device, the peak value of FBG fiber gratings is caught by system data processing and Algorithm Analysis, calculates current FBG's
Centre wavelength, Current Temperatures information is calculated by the linear relationship of itself and temperature.