CN205157423U - Can improve infrared gaseous detecting system who detects stability - Google Patents
Can improve infrared gaseous detecting system who detects stability Download PDFInfo
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- CN205157423U CN205157423U CN201520971007.8U CN201520971007U CN205157423U CN 205157423 U CN205157423 U CN 205157423U CN 201520971007 U CN201520971007 U CN 201520971007U CN 205157423 U CN205157423 U CN 205157423U
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Abstract
The utility model provides a can improve infrared gaseous detecting system who detects stability, belongs to the infrared gaseous technical field of detection, includes DFB laser instrument etc.. Before the DFB laser instrument lies in one minute two coupler of optic fibre, divide into two the tunnel with the light path by one minute two coupler of optic fibre, photoelectric detector A is arrived to its channel qi room of going the same way, and photoelectric detector A output meets amplifier circuit A, photoelectric detector B is received through one minute two coupler of optic fibre to another way light path, and photoelectric detector B output meets amplifier circuit B, and amplifier circuit A and B's output is connected to the stream input end of differential circuit respectively, and filter circuit is connected to its output, and filter circuit's output and microprocessor connect, and microprocessor connects control by temperature change circuit and current driving circuit respectively, and control by temperature change circuit and current driving circuit's output links to each other with the DFB laser instrument respectively, the utility model discloses simple structure, it is easy to realize, has the long term stability height, has overcome prior art's system measuring error, can be extensive be applied to the gaseous detection area of optic fibre.
Description
Technical field
Can the infrared gas detection system detecting stability be improved, belong to infrared gas detection technical field.
Background technology
The detection of micro-water content has important effect in power industry.Since the mid-80, along with developing rapidly of power industry, sulfur hexafluoride (SF6) electrical equipment is widely used, and specifically comprises SF6 isolating switch, GIS switchgear, the transformer that SF6 insulate, voltage transformer (VT), current transformer and all kinds of bushings etc.And at present building in electric pressure 110kv and above project, basis all uses SF6 switchgear.These electrical equipments, in electric system, play very important effect, and its reliability of operation is not only related to SF6 electrical equipment itself, and affects other equipment, the safety of even whole electrical network.
Be in operation, SF6 gas, by after arc discharge or high temperature, can resolve into the fluorine of monomer, sulphur and fluorine sulphur compound, and electric arc can be combined to again stable SF6 gas after disappearing.But when containing moisture in gas, fluorine sulphur compound can react with water and generate the very strong chemical substance etc. of the very strong hydrofluorite of corrosivity, sulfuric acid and other toxicity, thus corrosion electrical equipment, reduce apparatus insulated ability, jeopardize the life security of maintainer.The moisture will removing SF6 gas in instrument is completely impossible, but the moment grasps SF6 gas micro water content, takes corresponding Control Measure, reduces the moisture in SF6 gas, can ensure and improve the safe operation reliability of isolating switch.Except micro-water content in electric system high-tension switch cabinet, the water vapor body Concentration Testing in transformer oil is also indispensable.
Utilize Infrared spectra adsorption technology to detect moisture in SF6 isolating switch, its advantage is that reaction velocity is fast, highly sensitive, and can realize on-line checkingi.But because optical device is as laser instrument, coupling mechanism, collimating apparatus, optical fiber is easily subject to temperature, the impact of ambient stress factors vary and change light generation power and coupling efficiency, transmission light light intensity is changed, thus changes with the light intensity that gas absorption loss brings and obscure, bring measuring error.Have impact on measuring accuracy and the long-time stability of Infrared spectra adsorption technology.
The impact of temperature on light collimator is mentioned in paper " the angular deflection impact analysis of temperature on fiber collimating apparatus " [Sun Ming 1509-1512 page prompt in October, 2006 photon journal the 35th volume the 10th phase]; The impact of temperature on fiber one-to-two coupling mechanism is mentioned in paper " temperature-responsive of melting cone fiber one-to-two coupling mechanism " [Li Chuan, Zhang Yimo, Liu Tiegen, fourth victory sensing technology journal the 14th volume the 3rd 196-198 page in September calendar year 2001 phase].
Once the solution for this problem was had, its thinking produces analog references light signal by microprocessor calibrate and adjust laser instrument bright dipping, decrease the systematic error that the environmental factors such as Yin Wendu produce to a certain extent, but because laser instrument light power becomes nonlinear relationship with Injection Current, with the program obtain uneven without absorption place spectral line baseline, cause signal to noise ratio (S/N ratio) to reduce.
Summary of the invention
For overcoming the deficiencies in the prior art and defect, the utility model proposes a kind of infrared gas detection system that can improve detection stability, by eliminating the fluctuation of luminous power in the transmission light path brought due to environmental factor (except gas absorption) from the automatic control of gain amplifier, to overcome the systematic measurement error brought thus.
The technical solution of the utility model realizes in the following manner:
A kind of infrared gas detection system that can improve detection stability, comprise temperature control circuit, current driving circuit, Distributed Feedback Laser, optical fiber one-to-two coupling mechanism, air chamber, photodetector A and B, amplifying circuit A and B (from gain amplifier and peripheral circuit), difference channel, filtering circuit and microprocessor, before it is characterized in that Distributed Feedback Laser is positioned at optical fiber one-to-two coupling mechanism, by optical fiber one-to-two coupling mechanism, one tunnel light path is divided into two-way, wherein a road arrives the input end of photodetector A through air chamber, the output terminal of photodetector A is connected to the input end of amplifying circuit A, another road light path receives the input end of photodetector B through optical fiber one-to-two coupling mechanism, the output terminal of photodetector B is connected to the input end of amplifying circuit B, the output terminal of amplifying circuit A and B is connected respectively to the two-way input end of difference channel, the output terminal of difference channel connects the input end of filtering circuit, the output terminal of filtering circuit is connected with microprocessor, microprocessor is connected respectively to temperature control circuit and current driving circuit, and temperature control circuit is connected with Distributed Feedback Laser respectively with the output terminal of current driving circuit,
Described temperature control circuit uses the semiconductor laser diode controller LDC501 of Stamford Study system company;
Described amplifying circuit A and B comprises front and back stages AD603 amplifier chip and an AD8561 comparer chip separately, contact resistance R1 between the positive-negative input end of wherein prime AD603 amplifier chip, negative input end ground connection; Its output terminal is connected to the positive input terminal of rear class AD603 amplifier chip through resistance R2; Contact resistance R3 between the positive-negative input end of rear class AD603 amplifier chip, its negative input end ground connection, output terminal is connected to the output terminal of whole amplifying circuit after resistance R4 contacts with R5 or R13; The negative input end of AD8561 comparer chip is connected with the common point of resistance R4, R5 through resistance R6, its positive input terminal is connected to through resistance R9 by after potentiometer WR1 dividing potential drop, positive input terminal is through electric capacity C2 ground connection, its outlet internal ground connection, its the 8th pin is connected to the 2nd pin of two-stage AD603 amplifier chip through resistance R7, the 2nd pin ground connection after resistance R8 and electric capacity C1 is in parallel of two-stage AD603 amplifier chip;
Described current driving circuit is formed by connecting by the DA mouth of microprocessor and integrated transporting discharging LM358 chip;
Described photodetector A and B is all PIN photoelectric detector.
Described difference channel is amplifier AD8221 chip.
Described filtering circuit is universal active filter chip UAF42, is low-pass filter structure.
Described microprocessor is LPC1758 chip.
Described Distributed Feedback Laser is the distributed feedback laser of WSLS-137010C1424-20 butterfly-type encapsulation (DistributedFeedbackLaser), and wavelength is 1370 ± 2nm.
Utilize the method that said detecting system detects steam in air chamber, step is as follows:
1) said detecting system connected, connect the power supply in light path and each circuit, debugging light path and each circuit are in normal operating conditions; Gas to be measured is poured in air chamber;
2) by temperature control circuit, thermostatic control is carried out to Distributed Feedback Laser: utilizing microprocessor to produce curent change amplitude within the 0.03S time interval is 48mA, change procedure is raised to 72mA from low to high from 24mA, and then back and forth carry out to 24mA from high to low from 72mA, the curent change of setting is that the voltage signal exported by microprocessor realizes with the form of sine wave; The change of the output wavelength of Distributed Feedback Laser can be caused due to Distributed Feedback Laser drive current variations, the change in voltage arranged in the microprocessor exports and the output wavelength of Distributed Feedback Laser is changed, the variation range of the output wavelength of Distributed Feedback Laser corresponds to the variation range of its drive current, the variation range of the drive current namely between 24mA to 72mA contains the output wavelength of the 1368.597nm that Distributed Feedback Laser produces, and this output wavelength is the wavelength that water vapor absorption peak is corresponding;
3) using in the two-way light that separated by optical fiber one-to-two coupling mechanism not by a road of air chamber as with reference to light, through a road of air chamber as detection light, regulate the enlargement factor of amplifying circuit A and B and difference channel, observe the output signal of difference channel output terminal with oscillograph during adjustment, the amplitude of its output voltage outside water vapor absorption spike is long is made to be in 0mv to 100mv scope, it is identical that this illustrates that two-way amplifying circuit A with B outputs signal baseline, be no more than 3V at the voltage of water vapor absorption spike strong point, to meet the signal amplitude requirement of microcontroller acquires simultaneously;
4) after the enlargement factor of detection optical circuit is adjusted, gathered out after water vapor absorption at the signal that wavelength 1368.597nm and reference light one tunnel produce through being absorbed in Same Wavelength place without steam at the output terminal of filtering circuit by microprocessor, calculate the difference of these two signals through microprocessor and store this difference, by above-mentioned collection, calculating and storing process repeat 1000 times, after getting the mean value of these 1000 differences, under passing through the different moisture content of contrast before utilizing experiment, the linearity curve of the difference (Y-axis) obtained by the microwater device reading corresponding relation storing difference corresponding to synchronization detection system and moisture content (X-axis), contrast obtains vapour concentration,
5) gas detect to be measured is complete, closes detection system power supply everywhere.
The final water vapor absorption spike shape of systems axiol-ogy of the present utility model utilizes optical fiber one-to-two coupling mechanism that laser emitting light is divided into two, reference optical signal and detection light signal, by two-way photodetector A and B and amplifying circuit A and B, two paths of signals is subtracted each other rear acquisition by difference channel, one tunnel is the electric signal that light signal is converted to by photoelectric detector by air chamber, another road is as reference signal, namely light without air chamber directly by the electric signal produced after photoelectric detector, when environmental factor is (as temperature, stress) when changing, can occur to strengthen or decay by the signal light intensity of air chamber, namely the road sine wave (road of light signal conversion) entering difference channel can increase or reduce, and the sinusoidal wave electric signal of reference circuit is constant all the time, and (pure electric signal is affected by environment very little, change can be ignored), which results in final absorption peak waveform to distort, waveform generation distortion can make microprocessor calculated difference change, thus bring measuring error to measuring system, for solving this problem, can adopt from gain amplifier from controlling enlargement factor function, order output signal peak-to-peak value remains unchanged, to eliminate the impact of environmental factor change on detection system.
The utility model system is by realizing from gain amplifier the function improving infrared gas detection system stability:
1) two place's input amplifiers receive two place's photodetector output terminals respectively, and amplification circuit output end receives two input ends of difference channel respectively.
2) the sinusoidal wave electric signal of two-way, one tunnel is light beam is directly produced the amplifying circuit amplification of Bing Yougai road by photoelectric detector sinusoidal wave electric signal without air chamber, another road is the sine wave signal amplified by this amplifying circuit after transmission light opto-electronic conversion, the absorption peak waveform obtained after difference channel difference is the waveform that microprocessor finally gathers, when environmental factor does not change, in final collection waveform, both sides, gas absorption peak should in same level position.
3) when environmental factor changes, the light intensity that reference light there occurs in various degree respectively with detection light changes, but due in two-way as the action effect of amplifying circuit A and B from gain amplifier, by changing the variable quantity of the light intensity that the electric gain compensation external factor such as temperature cause in real time, eliminate the light intensity change because environmental factor causes, make the gas absorption peak-to-peak signal after eventually passing through difference channel not by the impact of light intensity change under non-absorbing effect, same level position is got back in both sides, gas absorption peak.
The utility model has following advantage: the utility model is convenient to be installed, and structure is simple.By the automatic control function from gain amplifier, eliminate the impact of the instability of environmental change and light source, the environment larger in the temperature difference also can run, degree of accuracy and highly sensitive, and the response time is short, vapour concentration can be monitored in time, easy and simple to handle, pollution-free, as long as change wavelength coverage, this way can be applied in the detection of other species concentration simultaneously and go, and applies very extensive.
Accompanying drawing explanation
Fig. 1 is structural representation of the present utility model.
Wherein: 1, Distributed Feedback Laser, 2, optical fiber one-to-two coupling mechanism, 3, air chamber, 4, photodetector A, 5, amplifying circuit A, 6, difference channel, 7, filtering circuit, 8, microprocessor, 9, temperature control circuit, 10, current driving circuit, 11, photodetector B, 12, amplifying circuit B.
Fig. 2 is the circuit diagram of amplifying circuit A or B of the present utility model, adopt two AD603 amplifier chips (being called pre-amplifier and post-amplifier afterwards), an AD8561 comparer chip is formed by connecting, wherein P1, P2 are BNC (snap-fit connector), as a kind of signal I/O mode, another kind of mode then carrys out signal transmission by row's pin J1, J2, J4, J4 is unsettled within the system, wherein J1 (P1) is from gain amplifying circuit input end, and J2 (P2) is amplification circuit output end.Wherein front and back stages AD603 chip 1 pin all receives trigger pip Vg+, in figure, NC represents and can not connect this resistance, 8 pins all connect power Vcc, 6 pins all meet common ground end Vss, AD603 chip 5,7 pin at different levels connects, two-stage amplifier 7 pin (output terminal) each connecting resistance R2, R4, post-amplifier output terminal is connected to the output terminal of whole amplifying circuit after resistance R4 contacts with R5 or R13, two positive-negative input end 3,4 pin connect R1, R2 two ends respectively and 3 pin connect input signal, 4 pin ground connection, 2 pin of two amplifier chips are connected; The negative input end of AD8561 comparer chip is connected with the common point of resistance R4, R5 through resistance R6, its positive input terminal is connected to through resistance R9 by after potentiometer WR1 dividing potential drop, positive input terminal is through electric capacity C2 ground connection, its outlet internal ground connection, its the 8th pin is connected to the 2nd pin of two-stage AD603 amplifier chip through resistance R7, the 2nd pin ground connection after resistance R8 and electric capacity C1 is in parallel of two-stage AD603 amplifier chip;
Fig. 3 is difference channel of the present utility model and filtering circuit circuit diagram, difference channel adopts amplifier 8221 chip, its negative input end contact resistance Rg, positive input terminal contact resistance Rh, 3 pin of 8221 chips connect intermediate ends and one end of current potential R, the other end of potentiometer R connects 2 pin of 8221 chips, and potentiometer R can carry out gain control to difference channel; 5,8 pin of 8221 chips connect negative, positive 12V power supply respectively, negative, positive 12V power supply be connected electric capacity C41, C40 between ground connection place respectively and carry out filtering; The other end of the output terminal 7 pin contact resistance Rm of 8221 chips, Rm, on the one hand through resistance Rn ground connection, is connected to the 4th pin of active power filtering chip UAF on the other hand; Filtering circuit is the low-pass filter be made up of active power filtering chip UAF, wherein resistance Ri is connected to 8 pin and 16 pin of filtering chip UAF, resistance Rk is connected to 9 pin and 14 pin of filtering chip UAF, the A/D end that its 1 pin connects microprocessor carries out data acquisition, 2,12,15 pin ground connection, 10 pin, 11 pin connect negative, positive 12V power supply respectively, and negative, positive 12V power supply is connected to ground to carry out filtering through electric capacity C43, C42 respectively; In low-pass filter, the resistance of Ri, Rk, Rm, Rn is with deciding filter cutoff frequency.
Embodiment
Below in conjunction with drawings and Examples, the utility model is described further, but is not limited thereto.
Embodiment:
The utility model embodiment as Figure 1-3, a kind of infrared gas detection system that can improve detection stability, comprise temperature control circuit 9, current driving circuit 10, Distributed Feedback Laser 1, optical fiber one-to-two coupling mechanism 2, air chamber 3, photodetector A (4) and B (11), amplifying circuit A (5) and B (12), difference channel 6, filtering circuit 7 and microprocessor 8, before it is characterized in that Distributed Feedback Laser 1 is positioned at optical fiber one-to-two coupling mechanism 2, by optical fiber one-to-two coupling mechanism 2, a tunnel light path is divided into two-way, wherein a road arrives the input end of photodetector A (4) through air chamber 3, the output terminal of photodetector A (4) is connected to the input end of amplifying circuit A (5), another road light path receives the input end of photodetector B (11) through optical fiber one-to-two coupling mechanism 2, the output terminal of photodetector B (11) is connected to the input end of amplifying circuit B (12), the output terminal of amplifying circuit A (5) and B (12) is connected respectively to the two-way input end of difference channel 6, the output terminal of difference channel 6 connects the input end of filtering circuit 7, the output terminal of filtering circuit 7 is connected with microprocessor 8, microprocessor 8 is connected respectively to temperature control circuit 9 and current driving circuit 10, temperature control circuit 9 is connected with Distributed Feedback Laser 1 respectively with the output terminal of current driving circuit 10,
Described temperature control circuit 9 uses the semiconductor laser diode controller LDC501 of Stamford Study system company;
Described amplifying circuit A and B comprises front and back stages AD603 amplifier chip and an AD8561 comparer chip separately, contact resistance R1 between the positive-negative input end of wherein prime AD603 amplifier chip, negative input end ground connection; Its output terminal is connected to the positive input terminal of rear class AD603 amplifier chip through resistance R2; Contact resistance R3 between the positive-negative input end of rear class AD603 amplifier chip, its negative input end ground connection, output terminal is connected to the output terminal of whole amplifying circuit after resistance R4 contacts with R5 or R13; The negative input end of AD8561 comparer chip is connected with the common point of resistance R4, R5 through resistance R6, its positive input terminal is connected to through resistance R9 by after potentiometer WR1 dividing potential drop, positive input terminal is through electric capacity C2 ground connection, its outlet internal ground connection, its the 8th pin is connected to the 2nd pin of two-stage AD603 amplifier chip through resistance R7, the 2nd pin ground connection after resistance R8 and electric capacity C1 is in parallel of two-stage AD603 amplifier chip;
Described current driving circuit 10 is formed by connecting by the DA mouth of microprocessor 8 and integrated transporting discharging LM358 chip;
Described photodetector A and B is all PIN photoelectric detector.
Described difference channel 6 is amplifier AD8221 chip.
Described filtering circuit 7 is universal active filter chip UAF42, is low-pass filter structure.
Described microprocessor 8 is LPC1758 chip.
Described Distributed Feedback Laser 1 is the distributed feedback laser of WSLS-137010C1424-20 butterfly-type encapsulation (DistributedFeedbackLaser), and wavelength is 1370 ± 2nm.
Claims (4)
1. one kind can be improved the infrared gas detection system detecting stability, comprise temperature control circuit, current driving circuit, Distributed Feedback Laser, optical fiber one-to-two coupling mechanism, air chamber, photodetector A and B, amplifying circuit A and B (from gain amplifier and peripheral circuit), difference channel, filtering circuit and microprocessor, before it is characterized in that Distributed Feedback Laser is positioned at optical fiber one-to-two coupling mechanism, by optical fiber one-to-two coupling mechanism, one tunnel light path is divided into two-way, wherein a road arrives the input end of photodetector A through air chamber, the output terminal of photodetector A is connected to the input end of amplifying circuit A, another road light path receives the input end of photodetector B through optical fiber one-to-two coupling mechanism, the output terminal of photodetector B is connected to the input end of amplifying circuit B, the output terminal of amplifying circuit A and B is connected respectively to the two-way input end of difference channel, the output terminal of difference channel connects the input end of filtering circuit, the output terminal of filtering circuit is connected with microprocessor, microprocessor is connected respectively to temperature control circuit and current driving circuit, and temperature control circuit is connected with Distributed Feedback Laser respectively with the output terminal of current driving circuit,
Described temperature control circuit uses the semiconductor laser diode controller LDC501 of Stamford Study system company;
Described amplifying circuit A and B comprises front and back stages AD603 amplifier chip and an AD8561 comparer chip separately, contact resistance R1 between the positive-negative input end of wherein prime AD603 amplifier chip, negative input end ground connection; Its output terminal is connected to the positive input terminal of rear class AD603 amplifier chip through resistance R2; Contact resistance R3 between the positive-negative input end of rear class AD603 amplifier chip, its negative input end ground connection, output terminal is connected to the output terminal of whole amplifying circuit after resistance R4 contacts with R5 or R13; The negative input end of AD8561 comparer chip is connected with the common point of resistance R4, R5 through resistance R6, its positive input terminal is connected to through resistance R9 by after potentiometer WR1 dividing potential drop, positive input terminal is through electric capacity C2 ground connection, its outlet internal ground connection, its the 8th pin is connected to the 2nd pin of two-stage AD603 amplifier chip through resistance R7, the 2nd pin ground connection after resistance R8 and electric capacity C1 is in parallel of two-stage AD603 amplifier chip;
Described current driving circuit is formed by connecting by the DA mouth of microprocessor and integrated transporting discharging LM358 chip;
Described difference channel is amplifier AD8221 chip;
Described filtering circuit is universal active filter chip UAF42, is low-pass filter structure.
2. a kind of infrared gas detection system that can improve detection stability as claimed in claim 1, is characterized in that described microprocessor is LPC1758 chip.
3. a kind of infrared gas detection system that can improve detection stability as claimed in claim 1, is characterized in that described photodetector A and B is all PIN photoelectric detector.
4. a kind of infrared gas detection system that can improve detection stability as claimed in claim 1, it is characterized in that described Distributed Feedback Laser is the distributed feedback laser of WSLS-137010C1424-20 butterfly-type encapsulation, wavelength is 1370 ± 2nm.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201520971007.8U CN205157423U (en) | 2015-11-27 | 2015-11-27 | Can improve infrared gaseous detecting system who detects stability |
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| CN201520971007.8U CN205157423U (en) | 2015-11-27 | 2015-11-27 | Can improve infrared gaseous detecting system who detects stability |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105241837A (en) * | 2015-11-27 | 2016-01-13 | 济南大学 | Infrared gas detection system capable of improving detection stability |
| CN110308076A (en) * | 2019-06-28 | 2019-10-08 | 中国矿业大学 | A kind of adaptive black water sinking speed detection device and working method |
-
2015
- 2015-11-27 CN CN201520971007.8U patent/CN205157423U/en not_active Withdrawn - After Issue
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105241837A (en) * | 2015-11-27 | 2016-01-13 | 济南大学 | Infrared gas detection system capable of improving detection stability |
| CN105241837B (en) * | 2015-11-27 | 2018-04-13 | 济南大学 | A kind of infrared gas detection system that can improve detection stability |
| CN110308076A (en) * | 2019-06-28 | 2019-10-08 | 中国矿业大学 | A kind of adaptive black water sinking speed detection device and working method |
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| C14 | Grant of patent or utility model | ||
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| AV01 | Patent right actively abandoned |
Granted publication date: 20160413 Effective date of abandoning: 20180413 |
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| AV01 | Patent right actively abandoned |