CN101813529A - Temperature measurement system of fiber bragg grating (FBG) and multi-point temperature measurement method - Google Patents
Temperature measurement system of fiber bragg grating (FBG) and multi-point temperature measurement method Download PDFInfo
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- CN101813529A CN101813529A CN200910228048A CN200910228048A CN101813529A CN 101813529 A CN101813529 A CN 101813529A CN 200910228048 A CN200910228048 A CN 200910228048A CN 200910228048 A CN200910228048 A CN 200910228048A CN 101813529 A CN101813529 A CN 101813529A
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Abstract
The invention belongs to the temperature measurement field, and relates to a temperature sensing system of fiber bragg grating (FBG), comprising a temperature measurement sensing head and an FBG temperature measurement controller. The broadband light emitted by the SLED light source of the FBG temperature measurement controller enters the temperature measurement sensing head through a first fiber directional coupler; the period of the temperature measurement sensing head changes long with the change of the external temperature and thus the central wavelength changes; the light emitted by the broadband SLED light source is reflected by the temperature measurement sensing head and then changes into a narrow-band signal the central wavelength of which corresponds to that of the sensing head, wherein the narrow-band signal sequentially enters a temperature discriminator through a first directional coupler and a second directional coupler. The invention also provides a multi-point temperature measurement method realized by using the temperature measurement system. By organically combining the automatic temperature control technology with the FBG technology, the invention improves the instability of the serial FBG temperature measurement system and lowers the cost. Moreover, the invention further provides a simplified FBG temperature measurement structure, which reduces the system complexity and further lowers the cost.
Description
Technical field
The present invention relates to temperature monitoring system, belong to field of sensing technologies based on fiber grating.
Background technology
In electric system, in the equipment long-time running process, positions such as various disconnecting links contact and bus row junction are because of wearing out or contact resistance is excessive generates heat.By the ruuning situation of monitoring contact temperature, can prevent effectively that the fire of power equipment from taking place, realize that therefore on-line temperature monitoring is the important means that guarantees the power equipment safety operation.Because the environment of power equipment high pressure causes the temperature of these heating positions to be difficult to timely on-line monitoring, therefore causes fire failure easily.At present, domestic most of power plant and transformer station adopt the temp measuring system based on electric signal sensor.Wherein infrared measurement of temperature is a non-cpntact measurement, is subject to environment and peripheral electromagnetic field and disturbs, and need manually-operated, can't realize on-line measurement, inefficiency; Electronic temperature transmitter is subject to electromagnetic interference (EMI), and the temperature sensor of machinery is subjected to the influence of environment also bigger, more than the measurement effect of several detection methods all not ideal enough.Therefore develop a kind of large-capacity distributing online in real time temperature monitoring system, the temperature of monitoring various power equipments contact has become the power industry task of top priority.
Along with the development of sensor technology, signal processing technology, computer technology, artificial intelligence technology, make that the state of temperature to each equipment of transformer station carries out on-line monitoring, in time finding potential faults and accumulative total property fault made prediction becomes possibility.It reduces maintenance frequency for the normal operation that guarantees substation equipment, and the operational reliability and the automaticity that improve electric system are significant.Because high voltage electric power equip ment is in high voltage, high-temperature, high-intensity magnetic field and the extremely strong electromagnetic interference environment, realize the thermometric to contact, must solve the adaptability of electronic measuring device under above-mentioned severe environmental conditions.
Utilize optical fiber grating temperature-measuring to be mostly to adopt the wavelength selectivity reflection original of FBG: when composite signal entered FBG, near the spectrum its reflection kernel wavelength almost all was reflected back, but not near the almost completely transmission of light the centre wavelength.The existing scheme of optical fiber grating temperature-measuring of utilizing is utilized the thermally sensitive characteristic of fiber grating, the wavelength that utilizes broadband spectral to enter behind the grating selects reflection characteristic to carry out the measurement of temperature, thereby reflection wave is introduced the fiber grating demodulation device wavelength is carried out demodulation, obtain temperature to be measured.Because the fiber grating demodulation device costs an arm and a leg, the general mode that adopts a plurality of fiber gratings to connect of this scheme realizes the measurement of multiple spot.The cost of each measurement point can be shared equally like this.Though this scheme has realized utilizing fiber grating that temperature is measured, because grating is connected, therefore in case wherein certain is damaged, total system just can not have been worked, and has reduced the stability of system.
The patent of invention content
The present invention is directed to above-mentioned prior art and deficiency, the invention provides two kinds of novel optical fiber and optical grating temp measuring systems with identical inventive concept, and provide two kinds of multi-point temperature measurement methods that utilize these two kinds of temp measuring systems to realize respectively, utilize the FBG that is with heat-conducting plate to make the temperature Discr. measured temperature is differentiated, improved measuring accuracy greatly.And overcome, and, employing greatly reduces cost owing to oneself having designed FBG thermometric controller owing to series connection has caused systematic jitters.
A kind of fiber grating temperature sensor of the present invention system, comprise thermometric sensing head and FBG thermometric controller, it is characterized in that FBG thermometric controller comprises temperature Discr., wide range SLED light source, first fiber directional coupler, second fiber directional coupler, photo-detector and the CPU that is with heat-conducting plate; The wide range light of SLED light emitted is by entering the thermometric sensing head after first fiber directional coupler, described thermometric sensing head is subjected to the variation of external temperature and change cycle and then change centre wavelength, the light that is sent by wide range SLED light source becomes the centre wavelength narrow band signal corresponding with sensing head centre wavelength after the reflection of thermometric sensing head, this narrow band signal is successively by entering the temperature Discr. behind first direction coupling mechanism and the second direction coupling mechanism; The centre wavelength of temperature Discr. is according to the heating or the cooling temperature change of heat-conducting plate, the narrow band signal that enters temperature Discr. reflected signal when identical with the centre wavelength of temperature Discr. is the strongest, reflected signal is admitted to photo-detector via the second direction coupling mechanism, light signal strength by the photo-detector collection is admitted to CPU, and CPU is according to the light signal strength maximum value calculation and monitor external temperature.
As preferred implementation, described system can also comprise another photo-detector of baseline optical signal being sent into CPU.
Another kind of fiber grating temperature sensor provided by the invention system, comprise the thermometric sensing head that places external environment condition, stick to narrow-band semiconductor laser instrument, directional coupler, photo-detector and CPU on the heat-conducting plate, described thermometric sensing head is subjected to the variation of external temperature and changes centre wavelength; Heat or lower the temperature by CPU control heat-conducting plate noise spectra of semiconductor lasers, its center emission wavelength is changed; The narrow band light of semiconductor laser emission enters the thermometric sensing head, is admitted to photo-detector through directional coupler after the narrow band light that is complementary with thermometric sensing head centre wavelength is reflected, and the signal of photo-detector output is admitted to CPU; The CPU internal memory contains the calibration data of expressing the relation between narrow-band semiconductor laser instrument emission wavelength and the external temperature, and CPU calculates external temperature according to the signal and the calibration data of photo-detector input.
The present invention provides the multi-point temperature measurement method that utilizes above-mentioned fiber grating temperature sensor system to realize respectively simultaneously, uses a photoswitch with two or more optical fiber grating temperature-measuring system parallel connections, by the temperature patrol inspection of time division multiplex realization to a plurality of points.
The present invention organically combines temperature automatic control technology and fiber grating, has given full play to the advantage of fiber grating, has improved the instability of general tandem type optical fiber grating temperature-measuring system, and has reduced cost, and the precision height of thermometric uses flexibly.The invention allows for a kind of parallel optical fibre grating thermometric structure that adopts photoswitch, can further reduce cost.Particularly, the present invention has following advantage:
1. high temperature resistant, measuring temperature range is 0 ℃～250 ℃;
2. measuring accuracy height, error generally+/-0.1 ℃;
3. reliability height, the up time was more than 20 years;
4. cost is low, and general one cost is about 3000 yuan;
5. volume is little, is convenient to install, and package dimension is Φ 5.5 * 65mm;
6. each probe works alone during many parallel connections, can not influence each other;
7. full quartz packaged, the insulativity height.
Description of drawings
Fig. 1 is a theory structure synoptic diagram of the present invention;
The optical fiber grating temperature-measuring structural representation of Fig. 2 for simplifying.
Embodiment
Specify below in conjunction with schematic diagram of the present invention:
As shown in Figure 1, the present invention includes thermometric sensing head 1, and FBG thermometric controller 2 these two large divisions.And comprised 3, two fiber directional couplers 4 of wide range SLED light source and 5 in the FBG thermometric controller 2, temperature Discr. 6,7, two photodetection instrument 8 of heat-conducting plate and 9, and the CPU of a control usefulness.Temperature Discr. 6 be stick on the heat-conducting plate 7 so that change the grating cycle and the centre wavelength of temperature Discr. 6 by heat-conducting plate 7 heating or cooling.CPU and heat-conducting plate 7, two photo-detectors 8 link to each other with 9 and SLED light source 3, control the running of whole FBG thermometric controller.
As Fig. 1, thermometric sensing head 1 is placed external environment condition, thereby change the centre wavelength that its reflects because the temperature of external environment condition can cause the grating cycle of thermometric sensing head to change.SLED light source 3 from thermometric controller 2 enters the thermometric sensing head after emitting wide range light direction of passage coupling mechanism 4, the thermometric sensing head of this moment has been because because external temperature has changed the cycle, so wide range light enters the information that narrow band light that the sensing head back reflection returns has just been carried external temperature.Owing to plated absorbing film in thermometric sensing head 1 other end, so the signal that sensing head 1 is crossed in transmission will be absorbed, can be because of reflection taking place and influence measurement afterwards at rear end face.Reflected narrow band light by entering temperature Discr. 6 after fiber directional coupler 4 and 5 by thermometric sensing head 1, CPU control this moment heat-conducting plate 7 is given 6 heating of temperature Discr. or cooling, monitors the luminous power of accepting on photo-detector 8 and 9 simultaneously.Heat-conducting plate 7 heating or cooling make the temperature of the temperature Discr. 6 on it rise or reduce, thereby the feasible wherein cyclomorphosis of FBG changes its reflection kernel wavelength.When its heating or the cooling temperature not to the time, the centre wavelength of temperature Discr. 6 does not match with the narrow band light that has the external temperature signal of transmitting the temperature Discr., thereby causes the most of transmission excess temperature of laser of narrowband Discr. 6 to enter photo-detector 9 and the received optical power of photo-detector 8 almost is very much 0.And when the temperature of heat-conducting plate 7 heating or cooling just in time reaches external temperature, the centre wavelength of temperature Discr. 6 is just in time mated with the narrow band light that has the external temperature signal that transmits the temperature Discr., thereby make the laser of narrowband major part by 6 reflections of temperature Discr., enter photo-detector 8 after the reflected light direction of passage coupling mechanism 5, when the received optical power of photo-detector 8 reaches maximum at this moment, control circuit stops heat-conducting plate being heated or lowers the temperature, and with the heat-conducting plate temperature that the records this moment temperature as sensing head.Meanwhile, all the time the light signal of surveying on the photo-detector 2 be can be used as reference, eliminate any interference that causes because of other factors of system automatically.
As want to measure the temperature of many places, and can use photoswitch with a plurality of such optical fiber grating temperature-measuring system parallel connections, can realize the temperature of a plurality of points is patrolled and examined by time division multiplex.Can also further reduce the cost of each point for measuring temperature like this.
As another alternative embodiment, the present invention also proposes a kind of optical fiber grating temperature-measuring structure of simplification.
As shown in Figure 2, this simplified structure has comprised the CPU of 4, one photo-detectors 5 of 3, heat-conducting plates of 2, one directional couplers of 1, one narrow-band semiconductor laser instrument of thermometric sensing head and a control usefulness.Semiconductor laser 2 sticks on the heat-conducting plate 4, and CPU and narrow-band semiconductor laser instrument 2, heat-conducting plate 4, and photo-detector 5 is continuous, with the control whole system operation.
As Fig. 2, the advanced behaviour earlier calibrated before measurement, obtains the relation between narrow-band semiconductor laser instrument emission wavelength and the external temperature.Thermometric sensing head 1 places external environment condition, thereby changes the centre wavelength that its reflects because the temperature of external environment condition can cause the grating cycle of thermometric sensing head to change.Heat-conducting plate 4 and semiconductor laser 2 adhere to each other, heat or lower the temperature by CPU6 control heat-conducting plate 4 noise spectra of semiconductor lasers 6, and the emission center wavelength temperature influence of semiconductor laser 2, the heating of 4 pairs of laser instruments of heat-conducting plate or cooling can cause the center emission wavelength of semiconductor laser to change.Carry out cyclical variation by CPU 6 control heat-conducting plates 4 temperature, thereby make the periodic scan variations of centre wavelength of narrow-band semiconductor laser instrument 2.The laser of narrowband of semiconductor laser 2 emissions enters thermometric sensing head 1, if the narrow band light of emission and the centre wavelength of thermometric sensing head 1 do not match, laser of narrowband is most of so can see through thermometric FBG, because coated absorbing film at thermometric sensing head 1 rear end face, the narrow band light that sees through thermometric sensing head 1 can be absorbed film and absorb, and does not influence measurement effect and can not reflect.Therefore the luminous power that this moment, photo-detector 5 recorded is very little.And if the centre wavelength of the narrow band light of laser instrument emission and thermometric sensing head 1 is mated, narrow band light is most of so can be entered photo-detector 5 by fiber directional coupler 3 by 1 reflection of thermometric sensing head, and the luminous power maximum that this moment, photo-detector 5 recorded.Control by CPU can record the temperature of the luminous power that records on the photo-detector 5 heat-conducting plate 4 when maximum and the emission center wavelength of semiconductor laser 2.Utilize the data of calibration in advance, CPU can calculate outside temperature this moment.
As want to measure the temperature of many places, and can make equally to use up and open the light a plurality of such optical fiber grating temperature-measuring system parallel connections, can realize the temperature of a plurality of points is patrolled and examined by time division multiplex.Can also further reduce the cost of each point for measuring temperature like this.
Claims (5)
1. fiber grating temperature sensor system, comprise thermometric sensing head and FBG thermometric controller, it is characterized in that FBG thermometric controller comprises temperature Discr., wide range SLED light source, first fiber directional coupler, second fiber directional coupler, photo-detector and the CPU that is with heat-conducting plate; The wide range light of SLED light emitted is by entering the thermometric sensing head after first fiber directional coupler, described thermometric sensing head is subjected to the variation of external temperature and change cycle and then change centre wavelength, the light that is sent by wide range SLED light source becomes the centre wavelength narrow band signal corresponding with sensing head centre wavelength after the reflection of thermometric sensing head, this narrow band signal is successively by entering the temperature Discr. behind first direction coupling mechanism and the second direction coupling mechanism; The centre wavelength of temperature Discr. is according to the heating or the cooling temperature change of heat-conducting plate, the narrow band signal that enters temperature Discr. reflected signal when identical with the centre wavelength of temperature Discr. is the strongest, reflected signal is admitted to photo-detector via the second direction coupling mechanism, light signal strength by the photo-detector collection is admitted to CPU, and CPU is according to the light signal strength maximum value calculation and monitor external temperature.
2. fiber grating temperature sensor according to claim 1 system is characterized in that described system also comprises another photo-detector of baseline optical signal being sent into CPU.
3. multi-point temperature measurement method that adopts the described fiber grating temperature sensor of claim 1 system to realize, it is characterized in that, use a photoswitch with two or more optical fiber grating temperature-measuring system parallel connections, by the temperature patrol inspection of time division multiplex realization to a plurality of points.
4. fiber grating temperature sensor system, comprise the thermometric sensing head that places external environment condition, stick to narrow-band semiconductor laser instrument, directional coupler, photo-detector and CPU on the heat-conducting plate, described thermometric sensing head is subjected to the variation of external temperature and changes centre wavelength; Heat or lower the temperature by CPU control heat-conducting plate noise spectra of semiconductor lasers, its center emission wavelength is changed; The narrow band light of semiconductor laser emission enters the thermometric sensing head, is admitted to photo-detector through directional coupler after the narrow band light that is complementary with thermometric sensing head centre wavelength is reflected, and the signal of photo-detector output is admitted to CPU; The CPU internal memory contains the calibration data of expressing the relation between narrow-band semiconductor laser instrument emission wavelength and the external temperature, and CPU calculates external temperature according to the signal and the calibration data of photo-detector input.
5. multi-point temperature measurement method that adopts the described fiber grating temperature sensor of claim 4 system to realize, it is characterized in that, use a photoswitch with two or more optical fiber grating temperature-measuring system parallel connections, by the temperature patrol inspection of time division multiplex realization to a plurality of points.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103364658A (en) * | 2013-06-28 | 2013-10-23 | 国网电力科学研究院武汉南瑞有限责任公司 | Method for predicting service life of transformer based on fiber grating temperature measurement system |
| CN105203225A (en) * | 2014-06-19 | 2015-12-30 | 国家电网公司 | Optical fiber grating temperature detecting method and device |
| CN110542444A (en) * | 2019-09-30 | 2019-12-06 | 深圳市简测智能技术有限公司 | fiber grating demodulation system |
-
2009
- 2009-11-06 CN CN200910228048A patent/CN101813529A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103364658A (en) * | 2013-06-28 | 2013-10-23 | 国网电力科学研究院武汉南瑞有限责任公司 | Method for predicting service life of transformer based on fiber grating temperature measurement system |
| CN105203225A (en) * | 2014-06-19 | 2015-12-30 | 国家电网公司 | Optical fiber grating temperature detecting method and device |
| CN105203225B (en) * | 2014-06-19 | 2019-02-26 | 国家电网公司 | A kind of optical fiber grating temperature detection method and device |
| CN110542444A (en) * | 2019-09-30 | 2019-12-06 | 深圳市简测智能技术有限公司 | fiber grating demodulation system |
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Application publication date: 20100825 |