CN108254338A - Gas content in transformer oil on-Line Monitor Device based on spectral absorption method - Google Patents

Abstract

The present invention relates to a kind of gas content in transformer oil on-Line Monitor Device based on spectral absorption method, the Dynamic headspace degassing module of negative pressure constant temperature therein includes degassing bottle, the air path part being connected with degassing bottle and oil circuit part；Further include oil-gas mixer；Multicomponent gas concentration detection module based on TDLAS includes signal generator, lock-in amplifier, laser driver, laser selector, laser base, laser, fiber coupler, collimator, focalizer, detector, data collecting card, control module, flowmeter and air pump；Tested gas measurement accuracy caused by by background gas cross jamming that the present invention solves current gas measurement device is low, time of measuring is long, device is complicated, the problem of measurement gas is single, measuring environment narrow range has high certainty of measurement, time of measuring is short, the advantages of device is simple, can measure multiple gases, and measuring environment range is wide.

Description

On-line monitoring device for gas content in transformer oil based on spectral absorption method

technical field

The invention relates to the technical field of on-line monitoring of transformer oil, in particular to an on-line monitoring device for gas content in transformer oil based on spectral absorption method.

Background technique

Transformers are not only the most expensive and important equipment in power facilities, but transformer failure or aging can cause very serious grid accidents. Therefore, real-time monitoring of the operating status and health status of transformers is helpful to improve the safety and stability of power facilities. Since there are many types of characteristic gases produced when a transformer fails, the monitoring of a single component gas can only be used for preliminary analysis of transformer faults. By monitoring the multi-component characteristic gas dissolved in the transformer oil, the detailed information of the transformer fault can be obtained, so as to judge the type and cause of the transformer fault more accurately. At present, the detection of dissolved gas content in transformer oil mainly includes two aspects of technology, namely oil-gas separation and multi-component gas detection.

The principle of oil and gas separation methods mainly includes dissolution equilibrium method and vacuum degassing method. The vacuum degassing method has the highest degassing efficiency, but in order to ensure the degassing effect, the vacuum degree of the system needs to be strictly controlled. The vacuum pump has high requirements, resulting in its complex structure and poor reliability, which is not suitable for online detection applications. On-line monitoring equipment mainly adopts the dissolution balance method, which is divided into mechanical oscillation method, dynamic headspace method and membrane separation method due to different balance methods. Among them, the mechanical oscillation method has high degassing rate and repeated It has good performance and is often used as the standard for degassing rate calibration of other degassing methods, but the operation process and device are relatively complicated, and it is not suitable for online equipment; The monitoring requirements are still in the research stage; the dynamic headspace method is currently the most widely used degassing method for online equipment. At present, high-purity _N2 is often used for purging in the dynamic headspace method, and the cost is relatively high; in addition, a stirring device or a bubbling device is installed at the bottom of the degassing bottle to separate the dissolved gas in the oil to the top of the degassing bottle. In the air chamber, but the separation effect needs to be improved.

At present, there are two types of gas monitoring methods: chemical analysis and spectroscopic analysis. Chemical methods mainly include chromatography, mass spectrometry and chromatography-mass spectrometry, etc., which have high sensitivity and reliable measurement results. The accuracy is high, but the response speed is slow and cannot be applied online. Spectroscopy includes Fourier Transform Infrared Spectroscopy (FTIR), Photoacoustic Spectroscopy (PAS) and Tunable Laser Absorption Spectroscopy (TDLAS). The equipment of Fourier transform infrared spectroscopy is relatively large, and the response speed is relatively slow; the existing photoacoustic gas measurement device mainly uses a single-ended single light source to enter the gas cell, and the singleness of the light source determines the accuracy of the measured gas. There are few types and great limitations. In some studies, one light source corresponds to one gas cell to solve the multi-light source coupling problem, but with the increase of components, the gas chamber will also increase accordingly, and the complexity of the device will increase.

Contents of the invention

The invention provides an on-line monitoring device for gas content in transformer oil based on the spectral absorption method, which solves the problem of low measurement accuracy, long measurement time, complicated device and difficulty in measuring gas caused by the cross interference of the background gas in the current gas measurement device. The problem of singleness and narrow measurement environment range; it has the advantages of high measurement accuracy, short measurement time, simple device, can measure a variety of gases, and has the advantages of wide measurement environment range.

In order to achieve the above object, the present invention adopts the following technical solutions to realize:

An online monitoring device for gas content in transformer oil based on spectral absorption method, including a dynamic headspace degassing module with negative pressure and constant temperature and a multi-component gas concentration detection module based on TDLAS; where:

The negative pressure and constant temperature dynamic headspace degassing module includes a degassing bottle, a gas circuit part connected to the degassing bottle and an oil circuit part; it is characterized in that it also includes an oil-gas mixer; the gas circuit part includes a The gas pipeline between the top gas outlet of the degassing bottle and the gas inlet of the oil-gas mixer, and the oil and gas filter device, pressure sensor, gas absorption pool, gas pump, first gas valve, a second air valve and a one-way valve; wherein the first air valve is also provided with an exhaust port, and the second air valve is also provided with a clean air inlet; the oil circuit part includes the oil inlet connected to the degassing bottle and The first oil pipeline between the oil delivery ports of the transformer, and the second oil pipeline connected between the oil outlet of the degasser and the oil return port of the transformer; The third oil valve, the first oil valve and the first liquid level sensor; the second oil pipeline is provided with the second oil valve and the fourth oil valve in sequence along the oil outlet direction, between the second oil valve and the fourth oil valve The second oil pipeline is connected to the oil inlet of the oil-gas mixer through the oil pump; the first oil pipeline between the first oil valve and the third oil valve is connected to the mixed oil-gas outlet of the oil-gas mixer; the degassing bottle is equipped with a second liquid position sensor and temperature sensor;

The TDLAS-based multi-component gas concentration detection module includes a signal generator, a lock-in amplifier, a laser driver, a laser selector, a laser base, a laser, an optical fiber coupler, a collimator, a focuser, a detector, and a data acquisition card, control module, flow meter and air pump; the signal generator is respectively connected to the lock-in amplifier and the laser driver through the output signal line, the laser driver is connected to the laser selector, the laser selector is connected to multiple laser bases, each laser base The lasers are installed correspondingly; each laser is connected to the fiber coupler through the output fiber, and the output pigtail of the fiber coupler is connected to the collimator. The final laser is received by the detector, the detector is connected to the lock-in amplifier through the output signal line, the output end of the lock-in amplifier is connected to the input end of the data acquisition card, the output end of the data acquisition card is connected to the control module through the data line, and the control module is connected to the signal Generator; the gas inlet of the gas absorption pool is connected to the output end of the flowmeter, and the gas outlet of the gas absorption pool is connected to the exhaust gas treatment device through an air pump.

The pressure sensor, air pump, first air valve, second air valve, third oil valve, first oil valve, first liquid level sensor, second oil valve, fourth oil valve, oil pump, second liquid level sensor and the temperature sensor are respectively connected to the control system.

The second liquid level sensor is arranged on the upper part of the degassing bottle, and the temperature sensor is arranged on the lower part of the degassing bottle.

The outside of the degassing bottle is provided with a temperature-controllable electric heating device.

The oil and gas filtering device is a polytetrafluoroethylene film.

The oil-gas mixer is a static mixing tube.

The clean air inlet of the second air valve communicates with the atmosphere through an air filter.

The gas absorption cell is a hollow optical fiber gas cell, a White cell, a Herriot cell or a long optical path gas cell.

The laser is a DFB laser.

The detectors are photodetectors.

Compared with prior art, the beneficial effect of the present invention is:

1. Compared with the existing degassing device, the dynamic headspace degassing module with negative pressure and constant temperature:

1) An oil-gas mixer is used to replace the conventional bubbling or electromagnetic stirring device. The gas and oil are mixed through the oil-gas mixer, and then fully contacted by the oil pump, which makes the oil-gas mixing more efficient and simplifies the device structure;

2) Extract clean air as the carrier gas, which is cheaper than purging with nitrogen;

3) Smaller gas absorption cells such as hollow fiber optic cells, White cells, Herriott cells, and long optical path gas cells are used to achieve ppb-level detection with mid-infrared lasers. And the gas demand is small, which is beneficial to simplify the structure of the degassing bottle and shorten the degassing time;

4) The degassing bottle adopts a negative pressure and high temperature environment to increase the concentration of the degassed gas and increase the degassing speed;

5) Adopt constant temperature and constant pressure degassing and gas detection environment, high degassing repeatability, high repeatability and precision of gas detection;

2. Compared with the existing multi-component gas detection device, the multi-component gas concentration detection module based on TDLAS:

1) Real-time detection of multi-component gases based on time-division scanning time-division multiplexing technology, and simultaneously detect the concentration of multiple component gases;

2) The design of a gas absorption cell is realized by using a fiber optic coupler, which greatly simplifies the volume of the multi-component gas detection device;

3) The entire device does not require consumable carrier gas, chromatographic columns that are prone to contamination and aging, and a complicated gas path control system, which can eliminate background gas cross-interference.

Description of drawings

Fig. 1 is a structural block diagram of the negative pressure and constant temperature dynamic headspace degassing module of the present invention.

Fig. 2 is a structural block diagram of the TDLAS-based multi-component gas concentration detection module of the present invention.

In the figure: 101. Gas absorption pool 102. Air pump 103. First air valve 104. Second air valve 105. Air filter 106. One-way valve 107. Pressure sensor 108. Oil and gas filter device 109. First oil valve 110. Second oil valve 111. Oil pump 112. Oil-air mixer 113. Third oil valve 114. Fourth oil valve 115. Degassing bottle 116. Temperature sensor 117. First liquid level sensor 118. Second liquid level sensor 201. Signal Generator 202. Lock-in amplifier 203. Laser driver 204. Laser selector 205. Laser base 206. Laser 207. Fiber coupler 208. Collimator 101. Gas absorption cell 209. Focuser 210. Detector 211. Data acquisition Card 212. Control module 213. Flow meter 102. Air pump

Detailed ways

The specific embodiment of the present invention will be further described below in conjunction with accompanying drawing:

The on-line monitoring device for gas content in transformer oil based on spectral absorption method of the present invention includes a dynamic headspace degassing module with negative pressure and constant temperature and a multi-component gas concentration detection module based on TDLAS; wherein:

As shown in Figure 1, the negative pressure and constant temperature dynamic headspace degassing module of the present invention includes a degassing bottle 115, a gas circuit part and an oil circuit part connected to the degassing bottle 115; it also includes an oil-gas mixer 112; The gas path part includes a gas path pipeline connected between the top gas outlet of the degassing bottle 115 and the gas inlet of the oil-gas mixer 112, and an oil-gas filter device 108 and a pressure sensor arranged sequentially on the gas path pipeline along the gas flow direction. 107, gas absorption pool 101, air pump 102, first air valve 103, second air valve 104 and one-way valve 106; wherein the first air valve 103 is also provided with an exhaust port, and the second air valve 104 is also provided with clean air Inlet; the oil circuit part includes the first oil circuit pipeline connected between the oil inlet of the degassing bottle 115 and the oil delivery port of the transformer, and is connected between the oil outlet of the degassing bottle 115 and the oil return port of the transformer The second oil pipeline; the first oil pipeline is sequentially provided with the third oil valve 113, the first oil valve 109 and the first liquid level sensor 117 along the oil inlet direction; the second oil pipeline is sequentially arranged along the oil outlet direction A second oil valve 110 and a fourth oil valve 114 are provided, and the second oil pipeline between the second oil valve 110 and the fourth oil valve 114 is connected to the oil inlet of the oil-air mixer 112 through an oil pump 111; the first oil valve 109 The first oil pipeline between the third oil valve 113 is connected to the mixed oil and gas outlet of the oil and gas mixer 112; the degassing bottle 115 is equipped with a second liquid level sensor 118 and a temperature sensor 116;

As shown in Figure 2, the TDLAS-based multi-component gas concentration detection module of the present invention includes a signal generator 201, a lock-in amplifier 202, a laser driver 203, a laser selector 204, a laser base 205, a laser 206, a fiber coupling Device 207, collimator 208, focuser 209, detector 210, data acquisition card 211, control module 212, flowmeter 213 and air pump 102; connection, the laser driver 203 is connected to the laser selector 204, and the laser selector 204 is connected to a plurality of laser bases 205, and each laser base 205 is correspondingly installed with a laser 206; each laser 206 is connected to a fiber coupler 207 through an output fiber, and the fiber coupling The output pigtail of device 207 is connected with collimator 208, and collimator 208 is installed on the incident port of gas absorption cell 101, and the exit port of gas absorption cell 101 is installed focuser 209, and the laser light after focusing is received by detector 210, and detector 210 is connected to the lock-in amplifier 202 by the output signal line, the output end of the lock-in amplifier 202 is connected to the input end of the data acquisition card 211, and the output end of the data acquisition card 211 is connected to the control module 212 by the data line, and the control module 212 is connected to the signal generator 201 The gas inlet of the gas absorption pool 101 is connected to the output end of the flow meter 213, and the gas outlet of the gas absorption pool 101 is connected to the exhaust gas treatment device through the air pump 102.

The pressure sensor 107, air pump 102, first air valve 103, second air valve 104, third oil valve 113, first oil valve 109, first liquid level sensor 117, second oil valve 110, fourth oil valve 114 , the oil pump 111 , the second liquid level sensor 118 and the temperature sensor 116 are respectively connected to the control system.

The second liquid level sensor 118 is arranged on the upper part of the degassing bottle 115 , and the temperature sensor 116 is arranged on the lower part of the degassing bottle 115 .

The outside of the degassing bottle 115 is provided with a temperature-controllable electric heating device.

The oil and gas filtering device 108 is a polytetrafluoroethylene membrane.

The oil-air mixer 112 is a static mixing tube.

The clean air inlet of the second air valve 104 communicates with the atmosphere through an air filter 105 .

The gas absorption cell 101 is a hollow fiber optic cell, a White cell, a Herriott cell or a long optical path gas cell.

The laser is a DFB laser.

The detectors are photodetectors.

The working principle of the on-line monitoring device for gas content in transformer oil based on the spectral absorption method of the present invention is as follows: the signal generator 201 generates a high-frequency sinusoidal signal, which is superimposed with the low-frequency triangular wave signal generated by the laser driver 203, and is jointly loaded on the laser 206 , while the low-frequency triangular wave is linearly scanning, the output optical power of the laser 206 is also accompanied by high-frequency sinusoidal modulation, so the wavelength of the laser 206 is modulated. Such high-frequency modulation can suppress background noise interference in the low-frequency band and improve the system performance. Measurement sensitivity. The laser 206 outputs the laser light with the wavelength of the absorption line of the gas to be measured, passes through the gas absorption cell 101, is received by the detector 210, and after being amplified by the amplifier circuit, the second harmonic signal containing the concentration information is demodulated by the lock-in amplifier 202; The output signal of the phase amplifier 202 is collected into the control module 212 through the A/D conversion circuit, and the data is processed, displayed, stored and so on.

The negative pressure and constant temperature dynamic headspace degassing module of the present invention uses the oil and gas mixer 112 to mix and homogenize the oil and gas in the transformer oil sample, and then introduces the oil and gas mixture into the negative pressure and high temperature degassing bottle 115 to improve oil and gas separation efficiency, while using a smaller gas absorption cell 101 to simplify the overall structure of the device; using a constant temperature and pressure environment to shorten the degassing time and high degassing repeatability.

The TDLAS-based multi-component gas concentration detection module of the present invention shares a gas absorption cell 101 with the negative pressure and constant temperature dynamic headspace degassing module, and realizes the multi-component gas detection based on the time-division scanning time-division multiplexing technology. Real-time detection. It controls and switches the working state of the laser driver 203 through the control module 212, and sequentially selects the measurement beam from a series of lasers 206 to be introduced into the detection optical path, so as to realize the time-sharing sequential detection of multi-component gases. The use of optical fiber couplers to simultaneously detect the concentration of multiple gases greatly simplifies the structure of the device. The whole set of equipment does not require consumable carrier gas, easy-to-contaminate and aging chromatographic columns and complex gas path control system, which can eliminate background gas cross-interference, can detect the concentration of multiple component gases at the same time, has high measurement accuracy and short measurement time.

Compared with other similar devices, the present invention has the advantages of: in terms of degassing, clean air is extracted as carrier gas without consumables; a gas absorption cell 101 with a smaller volume is used, such as a hollow fiber optic cell, a White cell, a Herriott cell Riot cells, long optical path gas chambers, etc. These gas absorption cells require less oil and gas, which facilitates the simplification of the degassing bottle structure and shortens the degassing time; The degassing and gas detection environment with constant temperature and pressure make the degassing repeatability of the device high, and the gas detection repeatability and precision are high; the static mixing tube is used instead of bubbling and electromagnetic stirring device to make the oil and gas mixing efficiency Higher, simplifying the device structure. In terms of gas detection, the traditional multi-gas chamber detection method is banned, as long as lasers 206 with different wavelengths are selected, the working state of the laser driver 203 is controlled and switched through the control module 212, so that the measurement beams are sequentially selected from a series of lasers 206 and introduced into To the detection optical path, the time-sharing sequential detection of multi-component gases is realized.

As shown in Figure 1, in the online monitoring device for gas content in transformer oil based on spectral absorption method according to the present invention, the dynamic headspace degassing module with negative pressure and constant temperature has the following working states:

1) The initial state of the system:

In the oil circuit part, the first oil valve 109 is off; the second oil valve 110 is off; the third oil valve 113 is off; the fourth oil valve 114 is off.

In the gas path, port 1 and port 3 of the first air valve 103 are connected; port 4 and port 6 of the second air valve 104 are connected.

The air pump 102 is stopped, and the oil pump 111 is stopped.

2) Oil filling status:

In the initial state of the system, the state of the second oil valve 110 is turned on; the third oil valve 113 is turned on; the oil pump 111 runs until the oil level reaches the position of the second liquid level sensor 118 and stops.

3) Oil discharge state:

In the initial state of the system, the first oil valve 109 is open; the fourth oil valve 114 is open; the oil pump 111 runs until the oil level reaches the position of the first liquid level sensor 117 and stops.

4) Purge status outside the gas path:

In the initial state of the system, the first oil valve 109 is connected; the connection of port 1 and port 3 of the first air valve 103 is changed to the connection of port 1 and port 2; the connection of port 4 and port 6 of the second air valve 104 is changed to Ports 5 and 6 are connected; the air pump 102 is in operation.

5) Purge status in the gas circuit:

In the initial state of the system, the first oil valve 109 is open; the air pump 102 is running.

6) Negative pressure state:

In the initial state of the system, the connection between port 1 and port 3 of the first air valve 103 is changed to port 1 and port 2; the air pump 102 runs and stops when the pressure value measured by the pressure sensor 107 reaches the set value.

7) The gas chamber cuts into the sample gas to measure the degassed state:

In the initial state of the system, the first oil valve 109 is open; the second oil valve 110 is open; the air pump 102 is running; the oil pump 111 is running.

8) Oil treatment status before oil discharge:

In the initial state of the system, the first oil valve 109 is connected; the connection of port 1 and port 3 of the first air valve 103 is changed to the connection of port 1 and port 2; the air pump 102 is running.

The on-off status of each oil valve, air valve, oil pump, and air pump in the above working state is shown in Table 1.

Table 1

The working process of the dynamic headspace degassing module with negative pressure and constant temperature is divided into the following eight steps: the first step, initialization; the second step, oil circuit flushing; the third step, purging; the fourth step, gas circuit pumping negative pressure ; The fifth step, sample oil; the sixth step, degassing and sampling; the seventh step, oil treatment before oil discharge; the eighth step, oil discharge. A total of 13 working processes are: initial state → negative pressure pumping → oil discharge → oil injection → oil discharge → purge outside the gas path → purge inside the gas path → purge outside the gas path → negative pressure pumping → oil injection → degassing and sampling → Oil Handling → Default. in:

The initialization process is to deal with abnormal conditions when the system is running. For example, when the pressure in the air chamber is unstable or there is still residual oil, the oil sample contamination can be prevented by pumping negative pressure. It mainly includes a negative pressure pumping and an oil discharge process.

The oil circuit flushing process is to eliminate the impact of the sample oil remaining in the degassing bottle 115 and the two oil circuit pipelines on this measurement after the last measurement, mainly including oil injection and oil discharge once each.

The purging process is mainly carried out in the gas path, including the first external purging, internal purging and the second external purging. During the external purging, the air passes through the air filter 105 and enters the gas path from the atmosphere to clean the entire device. After purging, it flows into the atmosphere; during internal purging, only the air pump 102 works, and the whole system is still closed.

The negative pressure process of the air circuit is to keep the system in a negative pressure state.

The oil injection process is realized by the oil circuit part, and the oil pump 111 is controlled to stop by the second liquid level sensor 118, including an oil injection process.

The degassing and sampling process is jointly realized by the degassing bottle 115 and the gas path. After the gas and oil are mixed through the oil-gas mixer 112, they are then passed through the oil pump 111 to fully contact the oil and gas.

The pre-drainage oil treatment process is carried out after sampling, and the purpose is to discharge excess gas in the sampled oil.

During the oil discharge process, the first liquid level sensor 117 controls the oil pump 111 to stop, and returns to the initial state of the system after the oil discharge, ready for the next working cycle.

As shown in Figure 2, in the on-line monitoring device for gas content in transformer oil based on spectral absorption method according to the present invention, the multi-component gas concentration detection module based on TDLAS is set with 4 lasers and simultaneously detects 6 kinds of gases as an example; the table 2 is the detailed parameters of the selected laser.

Table 2

The detection method is as follows:

1) Fill the gas to be measured into the gas absorption cell 101 through the flow meter 213, and the flow meter 213 is used to monitor the gas flow rate in the gas absorption cell.

2) The control module 212 generates two signals through the control signal generator 201 , one reference signal is sent to the reference terminal of the lock-in amplifier 202 , and one modulation signal is sent to the laser driver 203 . The control module is mainly used to process the collected data, and control the signal generator 201 to generate different signals, and then switch the working state of the laser driver 203 to realize time-division multiplex scanning.

3) The laser driver 203 cooperates with the laser selector 204 and the laser base 205 to modulate the output of the laser 206; different lasers 206 are switched to generate light of different wavelengths for time-sharing scanning.

4) The output pigtail of the laser 206 is coupled through the fiber coupler 207, and the collimated spot formed after being collimated by the collimator 208 scans the six gases sequentially in the gas absorption cell 101, and the outgoing light is sent by the focuser 209 Converged on the detector 210.

5) The signal output by the detector 210 is input to the signal terminal of the lock-in amplifier 202 , and the harmonic signal obtained by the lock-in amplifier 202 is sent to the data acquisition card 211 .

6) Send all the data in the data acquisition card 211 to the control module 212 for processing and calculation; the control module 212 corrects the measurement error caused by the change of the ambient temperature and pressure of the gas absorption cell 101 to obtain an accurate concentration value .

7) Send the detected gas to the waste gas treatment device through the gas pump 102 for waste gas treatment.

The control module can adopt single-chip microcomputer or PLC.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, any person familiar with the technical field within the technical scope disclosed in the present invention, according to the technical solution of the present invention Equivalent replacements or changes to the concepts thereof shall fall within the protection scope of the present invention.

Claims (10)

1. the gas content in transformer oil on-Line Monitor Device based on spectral absorption method, which is characterized in that including negative pressure constant temperature The Dynamic headspace degassing module and multicomponent gas concentration detection module based on TDLAS；Wherein：

The Dynamic headspace degassing module of the negative pressure constant temperature, the air path part being connected including degassing bottle, with degassing bottle and oil circuit portion Point；It is characterized in that, further include oil-gas mixer；The air path part includes being connected to top gas outlet and the oil gas of degassing bottle Gas path pipe between the gas access of mixer and the oil gas mistake being successively set on along gas flow direction on gas path pipe Filter device, pressure sensor, gas absorption cell, air pump, the first air valve, the second air valve and check valve；Wherein the first air valve is also set There is exhaust outlet, the second air valve is additionally provided with pure air entrance；The oil circuit part includes being connected to oil inlet and the change of degassing bottle Depressor send the first oil line pipe between hydraulic fluid port and be connected between the degassing oil outlet of bottle and transformer oil return opening second Oil line pipe；First oil line pipe upper edge oil inlet direction is equipped with third fuel tap, the first fuel tap and the first liquid level sensor successively；The The two fuel-displaced directions of oil line pipe upper edge successively be equipped with the second fuel tap and the 4th fuel tap, second between the second fuel tap and the 4th fuel tap Oil line pipe connects the oil-in of oil-gas mixer by oil pump；The first oil line pipe between first fuel tap and third fuel tap connects Connect the mixed oil and gas outlet of oil-gas mixer；The second liquid level sensor and temperature sensor are set in degassing bottle；

The multicomponent gas concentration detection module based on TDLAS, including signal generator, lock-in amplifier, Laser Driven Device, laser selector, laser base, laser, fiber coupler, collimator, focalizer, detector, data collecting card, Control module, flowmeter and air pump；Signal generator is connected by output signal line with lock-in amplifier, laser driver respectively It connects, laser driver is connect with laser selector, and laser selector is connect with more laser bases, every laser bottom It is corresponding respectively on seat that laser is installed；Each laser connects fiber coupler, the output tail of fiber coupler by output optical fibre Fibre connection collimator, collimator are mounted on the entry port of gas absorption cell, and the exit ports of gas absorption cell install focalizer, Laser after focusing is received by detector, and detector connects lock-in amplifier, the output of lock-in amplifier by output signal line The input terminal of end connection data collecting card, by data line link control module, control module connects the output terminal of data collecting card Connect signal generator；The output terminal of the air inlet connection flowmeter of gas absorption cell, the gas outlet of gas absorption cell passes through air pump Connect emission-control equipment.

2. the gas content in transformer oil on-Line Monitor Device according to claim 1 based on spectral absorption method, special Sign is, the pressure sensor, air pump, the first air valve, the second air valve, third fuel tap, the first fuel tap, the first level sensing Device, the second fuel tap, the 4th fuel tap, oil pump, the second liquid level sensor and temperature sensor connect control system respectively.

3. the gas content in transformer oil on-Line Monitor Device according to claim 1 or 2 based on spectral absorption method, It is characterized in that, second liquid level sensor is set on the top of degassing bottle, and temperature sensor is set on the lower part of degassing bottle.

4. the gas content in transformer oil on-Line Monitor Device according to claim 1 based on spectral absorption method, special Sign is that the outside of the degassing bottle is equipped with controllable temperature electric heater unit.

5. the gas content in transformer oil on-Line Monitor Device according to claim 1 based on spectral absorption method, special Sign is that the hydrocarbon filter device is polytetrafluoroethylene film.

6. the gas content in transformer oil on-Line Monitor Device according to claim 1 based on spectral absorption method, special Sign is that the oil-gas mixer is static mixing tube.

7. the gas content in transformer oil on-Line Monitor Device according to claim 1 based on spectral absorption method, special Sign is that the pure air entrance of second air valve passes through air filter and atmosphere.

8. the gas content in transformer oil on-Line Monitor Device according to claim 1 based on spectral absorption method, special Sign is that the gas absorption cell is hollow optic fibre gas chamber, Huai Techi, Maurice Herriott pond or long light path gas chamber.

9. the gas content in transformer oil on-Line Monitor Device according to claim 1 based on spectral absorption method, special Sign is that the laser is Distributed Feedback Laser.

10. the gas content in transformer oil on-Line Monitor Device according to claim 1 based on spectral absorption method, special Sign is that the detector is photodetector.