CN108254338B - Online monitoring device for gas content in transformer oil based on spectrum absorption method - Google Patents
Online monitoring device for gas content in transformer oil based on spectrum absorption method Download PDFInfo
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- CN108254338B CN108254338B CN201810230077.6A CN201810230077A CN108254338B CN 108254338 B CN108254338 B CN 108254338B CN 201810230077 A CN201810230077 A CN 201810230077A CN 108254338 B CN108254338 B CN 108254338B
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Abstract
The invention relates to an online monitoring device for gas content in transformer oil based on a spectrum absorption method, wherein a negative pressure constant temperature dynamic headspace degassing module comprises a degassing bottle, a gas path part and a gas path part, wherein the gas path part and the gas path part are connected with the degassing bottle; the device also comprises an oil-gas mixer; the TDLAS-based multicomponent gas concentration detection module comprises 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 focusing device, a detector, a data acquisition card, a control module, a flowmeter and an air pump; the invention solves the problems of low measurement precision, long measurement time, complex device, single measurement gas and narrow measurement environment range caused by the cross interference of the background gas on the measured gas of the current gas measurement device, and has the advantages of high measurement precision, short measurement time, simple device, capability of measuring various gases and wide measurement environment range.
Description
Technical Field
The invention relates to the technical field of online monitoring of transformer oil, in particular to an online monitoring device for gas content in transformer oil based on a spectrum absorption method.
Background
Transformers are not only the most expensive and important equipment in an electrical installation, but also faults or ageing of the transformers can cause very serious grid accidents. Therefore, the running state and the health state of the transformer are monitored in real time, and the safety and the stability of the electric power facilities are improved. Because the types of characteristic gases generated when the transformer breaks down are more, monitoring the single-component gas can only perform primary analysis on the transformer fault. By monitoring the multicomponent characteristic gas dissolved in the transformer oil, the detailed information of the transformer fault can be obtained, so that the type and the reason of the transformer fault can be accurately judged. Currently, the detection of the content of dissolved gas in transformer oil mainly comprises two aspects of technologies, namely oil-gas separation and multi-component gas detection.
The oil-gas separation method is mainly distinguished from a dissolution equilibrium method and a vacuum degassing method in principle, and degassing by the vacuum degassing methodThe efficiency is highest, but in order to ensure the degassing effect, the vacuum degree of the system needs to be strictly controlled, so the requirements on the vacuum degree and the vacuum pump of the system are very high, the structure is complex, the reliability is poor, and the system is not suitable for on-line detection application. The method is mainly used on the online monitoring equipment, and the dissolution balance method is divided into a mechanical oscillation method, a dynamic headspace method, a membrane separation method and the like because of different balance means, wherein the mechanical oscillation method is often used as a standard for calibrating the degassing rate of other degassing methods because of higher degassing rate and good repeatability, but the operation process and the device are relatively complex, and the method is not suitable for online equipment; the membrane separation method has simple device, but the degassing time is longer, and the requirements of on-line monitoring cannot be well met, and the method is still in a research stage at present; dynamic headspace is a degassing method currently used in online equipment in a large number. At present, high-purity N is often adopted in a dynamic headspace method 2 Purging, the cost is high; in addition, the stirring device or the bubbling device is arranged at the bottom of the degassing bottle, so that dissolved gas in oil is separated into a gas chamber at the top of the degassing bottle, but the separation effect is required to be improved.
Currently, there are two main types of methods for gas monitoring: the chemical analysis method and the spectral analysis method mainly comprise a chromatographic analysis method, a mass spectrometry method, a chromatography-mass spectrometry combined analysis method and the like, and have high sensitivity, high reliability of measurement results, but low response speed and cannot be applied on line. Spectroscopy includes fourier transform infrared spectroscopy (FTIR), photoacoustic spectroscopy (PAS), tunable laser absorption spectroscopy (TDLAS), and the like. The Fourier transform infrared spectroscopy has the advantages of huge equipment and relatively slow response speed; the existing photoacoustic gas measuring device mainly adopts a single-ended single light source to be incident into a gas cell, the variety of the measured gas is determined by the singleness of the light source, and the limitation is large. In some researches, the problem of coupling of multiple light sources is solved by adopting a mode that one light source corresponds to one gas pool, but with the increase of components, the gas chamber is correspondingly increased, and the complexity of the device is increased.
Disclosure of Invention
The invention provides a device for on-line monitoring of the gas content in transformer oil based on a spectrum absorption method, which solves the problems of low measurement precision, long measurement time, complex device, single measurement gas and narrow measurement environment range caused by the cross interference of background gas of the measured gas of the current gas measurement device; the device has the advantages of high measurement precision, short measurement time, simple device, capability of measuring various gases and wide measurement environment range.
In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:
the online monitoring device for the gas content in the transformer oil based on the spectrum absorption method comprises a dynamic headspace degassing module with negative pressure and constant temperature and a multi-component gas concentration detection module based on TDLAS; wherein:
the negative pressure constant temperature dynamic headspace degassing module comprises a degassing bottle, a gas path part and an oil path part which are connected with the degassing bottle; the device is characterized by also comprising an oil-gas mixer; the gas path part comprises a gas path pipeline connected between a top gas outlet of the degassing bottle and a gas inlet of the gas-gas mixer, and a gas-gas filtering device, a pressure sensor, a gas absorption tank, a gas pump, a first gas valve, a second gas valve and a one-way valve which are sequentially arranged on the gas path pipeline along the gas flow direction; 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 way part comprises a first oil way pipeline connected between an oil inlet of the degassing bottle and an oil feeding port of the transformer and a second oil way pipeline connected between an oil outlet of the degassing bottle and an oil return port of the transformer; a third oil valve, a first oil valve and a first liquid level sensor are sequentially arranged on the first oil way pipeline along the oil inlet direction; a second oil valve and a fourth oil valve are sequentially arranged on the second oil path pipeline along the oil outlet direction, and the second oil path pipeline between the second oil valve and the fourth oil valve is connected with an oil inlet of the oil-gas mixer through an oil pump; a first oil way pipeline between the first oil valve and the third oil valve is connected with a mixed oil gas outlet of the oil gas mixer; a second liquid level sensor and a temperature sensor are arranged in the degassing cylinder;
the TDLAS-based multicomponent gas concentration detection module comprises 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 focusing device, a detector, a data acquisition card, a control module, a flowmeter and an air pump; the signal generator is respectively connected with the lock-in amplifier and the laser driver through output signal lines, the laser driver is connected with the laser selector, the laser selector is connected with a plurality of laser bases, and each laser base is correspondingly provided with a laser; each laser is connected with an optical fiber coupler through an output optical fiber, an output tail fiber of the optical fiber coupler is connected with a collimator, the collimator is arranged at an incident port of a gas absorption tank, a focusing device is arranged at an emergent port of the gas absorption tank, focused laser is received by a detector, the detector is connected with a phase-locked amplifier through an output signal wire, an output end of the phase-locked amplifier is connected with an input end of a data acquisition card, an output end of the data acquisition card is connected with a control module through a data wire, and the control module is connected with a signal generator; the air inlet of the gas absorption tank is connected with the output end of the flowmeter, and the air outlet of the gas absorption tank is connected with the waste gas treatment device through an air pump.
The pressure sensor, the air pump, the first air valve, the second air valve, the third oil valve, the first liquid level sensor, the second oil valve, the fourth oil valve, the oil pump, the second liquid level sensor and the temperature sensor are respectively connected with the control system.
The second liquid level sensor is arranged at the upper part of the degassing cylinder, and the temperature sensor is arranged at the lower part of the degassing cylinder.
The outside of the degassing bottle is provided with a temperature-controllable electric heating device.
The oil gas filtering device is a polytetrafluoroethylene film.
The oil-gas mixer is a static mixing pipe.
The clean air inlet of the second air valve is communicated with the atmosphere through an air filter.
The gas absorption cell is a hollow fiber gas cell, a white cell, a Herriott cell or a long-optical-path gas cell.
The laser is a DFB laser.
The detector is a photoelectric detector.
Compared with the prior art, the invention has the beneficial effects that:
1. compared with the existing degassing device, the negative pressure constant-temperature dynamic headspace degassing module is characterized in that:
1) The conventional bubbling or electromagnetic stirring device is replaced by the oil-gas mixer, gas and oil are mixed through the oil-gas mixer, and then are fully contacted through the oil pump, so that the oil-gas mixing efficiency is higher, and the structure of the device is simplified;
2) The clean air is extracted as carrier gas, so that the cost is lower compared with the nitrogen purging;
3) The air absorption tank with smaller volumes such as a hollow fiber air chamber, a White (White), a tank Herriott (Herriott) tank and a long-optical-path air chamber is adopted, and the mid-infrared laser is matched to realize ppb level detection, so that the oil and air requirements are small, the structure of a degassing bottle is simplified, and the degassing time is shortened;
4) The degassing cylinder adopts a negative pressure high-temperature environment, so that the concentration of the degassing gas is improved, and the degassing speed is improved;
5) The constant-temperature and constant-pressure degassing and gas detection environments are adopted, so that the degassing repeatability is high, and the gas detection repeatability and the gas detection accuracy are high;
2. compared with the existing multicomponent gas detection device, the multicomponent gas concentration detection module based on TDLAS has the advantages that:
1) Real-time detection of the multi-component gas is realized based on a time division multiplexing technology of time-sharing scanning, and the concentration of the multi-component gas is detected simultaneously;
2) The design of a gas absorption tank is realized by utilizing the optical fiber coupler, so that the device volume for detecting the multi-component gas is greatly simplified;
3) The whole set of device does not need a chromatographic column and a complex gas path control system which consume carrier gas and are easy to pollute and age, and can eliminate the cross interference of background gas.
Drawings
FIG. 1 is a block diagram of a dynamic headspace degassing module with negative pressure and constant temperature according to the present invention.
Fig. 2 is a block diagram of a TDLAS based multicomponent gas concentration detection module according to the present invention.
In the figure: 101. the gas absorption cell 102, the gas pump 103, the first gas valve 104, the second gas valve 105, the air filter 106, the one-way valve 107, the pressure sensor 108, the oil and gas filtering device 109, the first oil valve 110, the second oil valve 111, the oil pump 112, the oil and gas mixer 113, the third oil valve 114, the fourth oil valve 115, the degassing bottle 116, the temperature sensor 117, the first liquid level sensor 118, the second liquid level sensor 201, the signal generator 202, the lock-in amplifier 203, the laser driver 204, the laser selector 205, the laser base 206, the laser 207, the optical fiber coupler 208, the collimator 101, the gas absorption cell 209, the focusing device 210, the detector 211, the acquisition card 212, the control module 213, the flow meter 102, the gas pump
Detailed Description
The following is a further description of embodiments of the invention, taken in conjunction with the accompanying drawings:
the invention relates to an online monitoring device for the gas content in transformer oil based on a spectrum absorption method, which comprises 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 fig. 1, the dynamic headspace degassing module with negative pressure and constant temperature comprises a degassing bottle 115, a gas path part and an oil path part, wherein the gas path part and the oil path part are connected with the degassing bottle 115; also included is an oil and gas mixer 112; the gas path part comprises a gas path pipeline connected between a top gas outlet of the degassing bottle 115 and a gas inlet of the gas-gas mixer 112, and a gas-gas filtering device 108, a pressure sensor 107, a gas absorption tank 101, a gas pump 102, a first gas valve 103, a second gas valve 104 and a one-way valve 106 which are sequentially arranged on the gas path pipeline along the gas flow direction; wherein the first air valve 103 is also provided with an exhaust port, and the second air valve 104 is also provided with a clean air inlet; the oil path part comprises a first oil path pipeline connected between an oil inlet of the degassing bottle 115 and an oil feeding port of the transformer, and a second oil path pipeline connected between an oil outlet of the degassing bottle 115 and an oil return port of the transformer; the first oil path pipeline is sequentially provided with a third oil valve 113, a first oil valve 109 and a first liquid level sensor 117 along the oil inlet direction; a second oil valve 110 and a fourth oil valve 114 are sequentially arranged on the second oil path pipeline along the oil outlet direction, and the second oil path pipeline between the second oil valve 110 and the fourth oil valve 114 is connected with an oil inlet of the oil-gas mixer 112 through an oil pump 111; a first oil path pipeline between the first oil valve 109 and the third oil valve 113 is connected with a mixed oil gas outlet of the oil gas mixer 112; a second liquid level sensor 118 and a temperature sensor 116 are arranged in the degassing cylinder 115;
as shown in fig. 2, the TDLAS-based multicomponent 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 coupler 207, a collimator 208, a focusing device 209, a detector 210, a data acquisition card 211, a control module 212, a flow meter 213, and a gas pump 102; the signal generator 201 is respectively connected with the lock-in amplifier 202 and the laser driver 203 through output signal lines, the laser driver 203 is connected with the laser selector 204, the laser selector 204 is connected with a plurality of laser bases 205, and each laser base 205 is correspondingly provided with a laser 206; each laser 206 is connected with an optical fiber coupler 207 through an output optical fiber, an output tail fiber of the optical fiber coupler 207 is connected with a collimator 208, the collimator 208 is arranged at an incident port of the gas absorption tank 101, a focusing device 209 is arranged at an emergent port of the gas absorption tank 101, focused laser is received by a detector 210, the detector 210 is connected with a lock-in amplifier 202 through an output signal wire, an output end of the lock-in amplifier 202 is connected with an input end of a data acquisition card 211, an output end of the data acquisition card 211 is connected with a control module 212 through a data wire, and the control module 212 is connected with a signal generator 201; an air inlet of the gas absorption tank 101 is connected with an output end of the flowmeter 213, and an air outlet of the gas absorption tank 101 is connected with an exhaust gas treatment device through the air pump 102.
The pressure sensor 107, the air pump 102, the first air valve 103, the second air valve 104, the third oil valve 113, the first oil valve 109, the first liquid level sensor 117, the second oil valve 110, the fourth oil valve 114, the oil pump 111, the second liquid level sensor 118 and the temperature sensor 116 are respectively connected with a control system.
The second liquid level sensor 118 is provided at the upper portion of the degassing cylinder 115, and the temperature sensor 116 is provided at the lower portion of the degassing cylinder 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 film.
The oil and gas 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 gas cell, a white cell, a herriott cell, or a long optical path gas cell.
The laser is a DFB laser.
The detector is a photoelectric detector.
The working principle of the online monitoring device for the gas content in the transformer oil based on the spectrum absorption method is as follows: the signal generator 201 generates a high-frequency sinusoidal signal, and the high-frequency sinusoidal signal is superimposed with a low-frequency triangular wave signal generated by the laser driver 203 and is loaded onto the laser 206 together, and the output light power of the laser 206 is also accompanied by high-frequency sinusoidal modulation while the low-frequency triangular wave is linearly scanned, so that the wavelength of the laser 206 is modulated, and the high-frequency modulation can inhibit background noise interference of a low frequency band and improve the measurement sensitivity of the system. The laser 206 outputs laser with the wavelength of the absorption spectrum of the gas to be detected, the laser passes through the gas absorption tank 101, is received by the detector 210, is amplified by the amplifying circuit, and then demodulates a second harmonic signal containing concentration information by the lock-in amplifier 202; the output signal of the lock-in amplifier 202 is collected into the control module 212 via the a/D conversion circuit, and data is processed, displayed, stored, etc.
According to the negative pressure constant temperature dynamic headspace degassing module, the oil gas in the oil sample of the transformer is mixed and homogenized by adopting the oil gas mixer 112, then the oil gas mixture is introduced into the negative pressure high temperature degassing bottle 115, so that the oil gas separation efficiency is improved, and meanwhile, the whole structure of the device is simplified by adopting the gas absorption tank 101 with smaller volume; the constant temperature and constant pressure environment is adopted, so that the degassing time is short, and the degassing repeatability is high.
The TDLAS-based multi-component gas concentration detection module shares a gas absorption tank 101 with the dynamic headspace degassing module with negative pressure and constant temperature, and realizes real-time detection of multi-component gas based on a time-division multiplexing technology of time-division scanning. The control module 212 is used for controlling and switching the working state of the laser driver 203, and sequentially selecting measuring beams from a series of lasers 206 to be led into a detection light path so as to realize time-sharing sequential detection of the multi-component gas. The concentration of various gases is detected simultaneously by utilizing the optical fiber coupler, so that the structure of the device is greatly simplified. The whole set of device does not need a chromatographic column and a complex gas path control system which consume carrier gas and are easy to pollute and age, can eliminate the cross interference of background gas, can detect the concentration of a plurality of component gases at the same time, has high measurement precision and short measurement time.
Compared with other similar devices, the invention has the advantages that: in the aspect of degassing, clean air is extracted as carrier gas, and consumable materials are not needed; the gas absorption tank 101 with smaller volume is adopted, such as a hollow optical fiber gas chamber, a White tank, a Herriott tank, a long optical path gas chamber and the like, and the gas absorption tank has small oil and gas requirements, so that the structure of a degassing bottle is convenient to simplify, and the degassing time is shortened; meanwhile, a negative pressure high-temperature environment is adopted, so that the concentration of the extracted gas is improved, and the degassing speed is improved; the degassing repeatability of the device and the gas detection accuracy are high due to the constant-temperature and constant-pressure degassing and gas detection environment; the static mixing tube is used for replacing bubbling and electromagnetic stirring devices, so that the oil-gas mixing efficiency is higher, and the device structure is simplified. In the aspect of gas detection, the conventional multi-gas chamber detection method is banned, and only lasers 206 with different wavelengths are selected, and the working states of the laser driver 203 are controlled and switched through the control module 212, so that measuring beams are sequentially selected from a series of lasers 206 to be led into a detection light path, and time-sharing sequential detection of multi-component gas is realized.
As shown in fig. 1, in the online monitoring device for gas content in transformer oil based on the spectrum absorption method, the dynamic headspace degassing module with constant temperature under negative pressure has the following working states:
1) System initial state:
an oil path portion, the first oil valve 109 being broken; a second oil valve break 110; the third oil valve 113 is opened; the fourth oil valve 114 is opened.
The air path part is communicated with the 1 port and the 3 port of the first air valve 103; the 4 ports and the 6 ports of the second air valve 104 are communicated.
The air pump 102 is stopped and the oil pump 111 is stopped.
2) Oiling state:
in the initial state of the system, the state of the second oil valve 110 is turned on; the third oil valve 113 is open; the oil pump 111 is stopped until the oil level reaches the position of the second level sensor 118.
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 is stopped until the oil level reaches the position of the first level sensor 117.
4) State of off-gas purge:
in the initial state of the system, the first oil valve 109 is open; changing the communication between 1 port and 3 ports of the first air valve 103 into 1 port and 2 port communication; changing the communication between the 4 ports and the 6 ports of the second air valve 104 into the communication between the 5 ports and the 6 ports; the air pump 102 operates.
5) Purging state in the gas circuit:
in the initial state of the system, the first oil valve 109 is open; the air pump 102 operates.
6) And (3) pumping negative pressure:
in the initial state of the system, the communication between 1 port and 3 ports of the first air valve 103 is changed into the communication between 1 port and 2 ports; the air pump 102 is operated and stopped when the pressure value measured by the pressure sensor 107 reaches a set value.
7) The gas cell was cut into the sample gas to measure the degassing state:
in the initial state of the system, the first oil valve 109 is opened; the second oil valve 110 is open; the air pump 102 is operated; the oil pump 111 operates.
8) Oil treatment state before oil discharge:
in the initial state of the system, the first oil valve 109 is open; the communication between 1 port and 3 ports of the first air valve 103 is changed into 1 port and 2 port communication; the air pump 102 operates.
The on-off conditions of each oil valve, the air valve, the oil pump and the air pump in the working state are shown in table 1.
TABLE 1
The working process of the dynamic headspace degassing module with constant negative pressure and constant temperature comprises the following eight steps: step one, initializing; secondly, flushing an oil way; thirdly, purging; fourth, the air path is vacuumized; fifthly, injecting oil; sixthly, degassing and sampling; seventh, oil treatment before oil discharge; eighth, discharging oil. The total 13 working processes are as follows: initial state, negative pressure pumping, oil discharging, oil filling, oil discharging, gas path external blowing, gas path internal blowing, gas path external blowing, negative pressure pumping, oil filling, degassing sampling, oil treatment and defaulting. Wherein:
the initialization process is to deal with abnormal conditions occurring during the operation of the system, such as unstable pressure in the air chamber or residual oil, and can prevent the pollution of the oil sample by pumping negative pressure, and mainly comprises a process of pumping negative pressure once and discharging oil once.
The oil way flushing process is to eliminate the influence of residual sample oil in the degassing cylinder 115 and 2 oil way pipelines on the measurement after the last measurement is completed, and mainly comprises oiling and oil discharging.
The purging process is mainly performed in the gas path part, comprising a first external purging, an internal purging and a second external purging, wherein the air in the external purging enters the gas path part from the atmosphere through the air filter 105, and then flows into the atmosphere after the whole device is purged; only the air pump 102 is operated during the internal purge, and the entire system is still closed.
The negative pressure pumping process of the air circuit is used for keeping the system in a negative pressure state.
The oil injection process is implemented by the oil path part, and the oil pump 111 is controlled to stop through the second liquid level sensor 118, including a primary oil injection process.
The degassing and sampling process is realized by the degassing bottle 115 and the gas path part, and after the gas and the oil are mixed by the oil-gas mixer 112, the oil-gas is fully contacted by the oil pump 111.
The pre-discharge treatment process is performed after sampling in order to discharge the excess gas in the sample oil.
The oil discharge process is stopped by the first liquid level sensor 117 controlling the oil pump 111, and the system returns to the initial state after oil discharge, and the next working cycle is ready.
As shown in fig. 2, in the online monitoring device for gas content in transformer oil based on the spectral absorption method, a multi-component gas concentration detection module based on TDLAS is used for setting 4 lasers, and 6 gases are detected at the same time as an example; table 2 shows the detailed parameters of the selected lasers.
TABLE 2
The detection method comprises the following steps:
1) The gas to be measured is filled into the gas absorption cell 101 through the flow meter 213, and the flow meter 213 is used for monitoring the gas flow in the gas absorption cell.
2) The control module 212 generates two signals by controlling the signal generator 201, one of which is sent to the reference terminal of the lock-in amplifier 202 and one of which is sent to the laser driver 203. The control module is mainly used for processing the collected data, and controlling the signal generator 201 to generate different signals, so as to switch the working state of the laser driver 203, thereby realizing time-sharing multi-path scanning.
3) The laser driver 203 cooperates with the laser selector 204 and the laser mount 205 to modulate the output of the laser 206; by switching the different lasers 206, light of different wavelengths is generated and time-sharing scanning is performed.
4) The output tail fiber of the laser 206 is coupled through an optical fiber coupler 207, the collimated light spots formed after being collimated by a collimator 208 sequentially scan 6 gases in the gas absorption tank 101, and the emergent light is converged on a detector 210 by a focusing device 209.
5) The signal output by the detector 210 is input to the signal end 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) All data in the data acquisition card 211 are transmitted to the control module 212 for processing and operation; the control module 212 corrects measurement errors caused by changes in the ambient temperature and pressure of the gas absorption cell 101 to obtain an accurate concentration value.
7) The detected gas is sent to the exhaust gas treatment device by the gas pump 102 for exhaust gas treatment.
The control module is realized by a singlechip or a PLC.
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme and the concept of the present invention, and should be covered by the scope of the present invention.
Claims (8)
1. The online monitoring device for the gas content in the transformer oil based on the spectrum absorption method is characterized by comprising a dynamic headspace degassing module with negative pressure and constant temperature and a multi-component gas concentration detection module based on TDLAS; wherein:
the negative pressure constant temperature dynamic headspace degassing module comprises a degassing bottle, a gas path part and an oil path part which are connected with the degassing bottle; the device is characterized by also comprising an oil-gas mixer; the gas path part comprises a gas path pipeline connected between a top gas outlet of the degassing bottle and a gas inlet of the gas-gas mixer, and a gas-gas filtering device, a pressure sensor, a gas absorption tank, a gas pump, a first gas valve, a second gas valve and a one-way valve which are sequentially arranged on the gas path pipeline along the gas flow direction; 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 way part comprises a first oil way pipeline connected between an oil inlet of the degassing bottle and an oil feeding port of the transformer and a second oil way pipeline connected between an oil outlet of the degassing bottle and an oil return port of the transformer; a third oil valve, a first oil valve and a first liquid level sensor are sequentially arranged on the first oil way pipeline along the oil inlet direction; a second oil valve and a fourth oil valve are sequentially arranged on the second oil path pipeline along the oil outlet direction, and the second oil path pipeline between the second oil valve and the fourth oil valve is connected with an oil inlet of the oil-gas mixer through an oil pump; a first oil way pipeline between the first oil valve and the third oil valve is connected with a mixed oil gas outlet of the oil gas mixer; a second liquid level sensor and a temperature sensor are arranged in the degassing cylinder; the outside of the degassing cylinder is provided with a temperature-controllable electric heating device;
the TDLAS-based multicomponent gas concentration detection module comprises 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 focusing device, a detector, a data acquisition card, a control module, a flowmeter and an air pump; the signal generator is respectively connected with the lock-in amplifier and the laser driver through output signal lines, the laser driver is connected with the laser selector, the laser selector is connected with a plurality of laser bases, and each laser base is correspondingly provided with a laser; each laser is connected with an optical fiber coupler through an output optical fiber, an output tail fiber of the optical fiber coupler is connected with a collimator, the collimator is arranged at an incident port of a gas absorption tank, a focusing device is arranged at an emergent port of the gas absorption tank, focused laser is received by a detector, the detector is connected with a phase-locked amplifier through an output signal wire, an output end of the phase-locked amplifier is connected with an input end of a data acquisition card, an output end of the data acquisition card is connected with a control module through a data wire, and the control module is connected with a signal generator; the air inlet of the gas absorption tank is connected with the output end of the flowmeter, and the air outlet of the gas absorption tank is connected with the waste gas treatment device through an air pump;
the pressure sensor, the air pump, the first air valve, the second air valve, the third oil valve, the first liquid level sensor, the second oil valve, the fourth oil valve, the oil pump, the second liquid level sensor and the temperature sensor are respectively connected with the control system.
2. The online monitoring device for the gas content in the transformer oil based on the spectrum absorption method according to claim 1, wherein the second liquid level sensor is arranged at the upper part of the degassing cylinder, and the temperature sensor is arranged at the lower part of the degassing cylinder.
3. The online monitoring device for gas content in transformer oil based on spectrum absorption method according to claim 1, wherein the oil-gas filtering device is a polytetrafluoroethylene film.
4. The online monitoring device for gas content in transformer oil based on spectrum absorption method according to claim 1, wherein the oil-gas mixer is a static mixing tube.
5. The online monitoring device for gas content in transformer oil based on spectrum absorption method according to claim 1, wherein the clean air inlet of the second air valve is communicated with the atmosphere through an air filter.
6. The online monitoring device for the gas content in the transformer oil based on the spectrum absorption method according to claim 1, wherein the gas absorption tank is a hollow fiber gas chamber, a white tank, a herriott tank or a long-optical-path gas chamber.
7. The online monitoring device for gas content in transformer oil based on spectrum absorption method according to claim 1, wherein the laser is a DFB laser.
8. The online monitoring device for gas content in transformer oil based on spectrum absorption method according to claim 1, wherein the detector is a photoelectric detector.
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