CN115032165A - Photoacoustic spectroscopy insulating oil dissolved gas detection system based on MEMS technology - Google Patents
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
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Abstract
The invention discloses a photoacoustic spectroscopy insulating oil dissolved gas detection system based on MEMS technology, which comprises a sample oil sampling module, a light source photoacoustic cell selection module, a two-stage absorption enhancement module, a gas separation module, a gas analysis module and a data transmission module, and has the advantages of simple structure, no maintenance, no carrier gas, no need of frequent calibration and no radiation source, high-precision measurement results enable the system to accurately identify potential faults, test data and diagnosis information can be timely transmitted, the safety and reliability of the operation of equipment are ensured, the regular maintenance mode of the equipment is changed into real-time monitoring and preventive detection or maintenance, the occurrence of major power accidents is favorably reduced, the two-stage absorption enhancement photoacoustic spectroscopy technology is adopted, the system has the advantages of high sensitivity, low drift and continuous on-line monitoring, and the problems that the traditional gas chromatography monitor needs consumable carrier gas, and the gas is used for continuous on-line monitoring, Standard gas and chromatographic column are easy to age and can not be stably operated for a long time.
Description
Technical Field
The invention relates to the technical field of detection of dissolved gas in insulating oil, in particular to a photoacoustic spectroscopy detection system for dissolved gas in insulating oil based on an MEMS (micro-electromechanical systems) technology.
Background
The insulation of electrical equipment is mainly composed of mineral insulating oil and organic insulating materials immersed in the oil, wherein the mineral insulating oil, i.e. transformer oil, is a fractionated product of petroleum, and the organic insulating material is mainly composed of cellulose, in the normal operation state of the power equipment, because the oil and solid insulation can be gradually aged and deteriorated, and can decompose a very small amount of gas, when the internal of the power equipment has overheating fault, discharging fault or damp condition, the production of these gases increases rapidly, the gases are mostly dissolved in the insulating oil, a small portion rises above the surface of the insulating oil, the amount of the various constituents of the gases in the oil is directly related to the nature and extent of the failure, therefore, during the operation of the equipment, the composition and the content of the gas dissolved in the oil are measured periodically, the method has very important significance for early finding out latent faults existing in the oil-filled power equipment;
at present, manual regular oil pumping mode detection and gas chromatography online monitoring are mainly adopted for detection, the manual regular oil pumping mode detection is low in working efficiency, multiple in manual operation, poor in repeatability and high in labor intensity, potential fault factors cannot be found in time, a consumable carrier gas is used in the gas chromatography online monitoring mode, the gas cylinder is high in maintenance cost, for most remote substations, replacement of a gas steel cylinder is a very troublesome matter, in addition, accumulation of high-boiling-point components in gas separated from transformer oil in a chromatographic column can cause reduction of separation effect, periodic aging or replacement is needed, gas chromatography technical pipelines are complex, components are multiple, and stability and reliability of long-term operation of instruments are not enough.
Disclosure of Invention
The invention provides a photoacoustic spectroscopy insulating oil dissolved gas detection system based on an MEMS (micro electro mechanical system) technology, which can effectively solve the problems that the detection working efficiency is low, the number of manual operations is large, the repeatability is poor and the labor intensity is high, potential fault factors cannot be found in time in the method which is provided by the background technology, the maintenance cost is high due to the use of consumable carrier gas in the gas chromatography online monitoring method, the replacement of gas steel cylinders is a very troublesome matter for most remote substations, in addition, the accumulation of high-boiling-point components in the separated gas in transformer oil on a chromatographic column can also cause the reduction of the separation effect, the periodic aging or replacement is needed, the gas chromatography technology has complex pipelines and many components, and the instrument has insufficient stability and reliability in long-term operation.
In order to achieve the purpose, the invention provides the following technical scheme: a photoacoustic spectroscopy insulating oil dissolved gas detection system based on MEMS technology comprises a sample oil sampling module, a light source photoacoustic cell selection module, a two-stage absorption enhancement module, a gas separation module, a gas analysis module and a data transmission module;
the detection system irradiates a sample sealed in the photoacoustic cell through a modulated monochromatic light source, the sample absorbs light energy and is de-excited in a mode of releasing heat energy, the released heat energy enables the sample and surrounding media to generate periodic heating according to the modulation frequency of light, so that the media generate periodic pressure fluctuation, the pressure fluctuation is detected through a photoacoustic spectrum detector with extremely high sensitivity, and photoacoustic signals are obtained through amplification;
because each infrared active compound has a specific infrared absorption spectrum, the wavelength of monochromatic light is changed, and photoacoustic signals changing along with the wavelength can be detected, so that quantitative analysis of the compounds is realized.
According to the technical scheme, the sample oil sampling module mainly acquires sample oil in a transformer oil tank to be detected, and the acquisition of the sample oil needs to consider various factors: the method comprises the following steps of (1) fully considering the factors and combining with on-site investigation, selecting a transformer on-line monitoring port for sampling, wherein the positions of the sampling ports of different types of transformers are different;
after the sample oil is detected and analyzed, the sample oil is processed in a mode of returning to an oil tank of the transformer.
According to the technical scheme, when the light source is selected, the light source photoacoustic cell selection module uses a point-modulated MEMS infrared light source to replace a traditional mechanical chopper dimming mode, and the MEMS infrared light source is mainly an infrared light source device based on a micro electro mechanical system manufacturing process;
when the photoacoustic cell is selected, the tubular gold-plated photoacoustic air chamber is mainly adopted, so that the detector is isolated from the gas, the pollution of oil gas to the detector is reduced, and the noise interference of a mobile phase is avoided.
According to the technical scheme, when the light source photoacoustic cell selection module selects the MEMS infrared light source, the radiation spectrum distribution characteristic test is carried out on the MEMS infrared light source by adopting the SR5000 spectral radiometer, so that the radiation spectrum distribution characteristic and the temperature characteristic of the MEMS infrared light source are determined.
According to the technical scheme, the double-stage absorption enhancement module adopts a double-stage absorption enhancement type photoacoustic spectroscopy technology, so that the device has high sensitivity, high reliability and high stability;
a double-stage absorption enhancement structure is adopted to isolate a gas sample from the photoacoustic detector, the total volume of the whole gas chamber is less than 3ML, most of infrared energy after passing through the first-stage analysis gas chamber is absorbed in the second-stage photoacoustic gas chamber, and gas generated after oil-gas separation does not contact with the detection element.
According to the technical scheme, the gas separation module is mainly used for analyzing dissolved gas components in oil by separating gas from the oil, and then the components and the content are analyzed by adopting a photoacoustic spectrometry method, wherein the degassing method comprises a dissolution equilibrium method, a thin film vacuum method and a mechanical vacuum method;
the method comprises the steps of reestablishing the balance between dissolved gas and high-purity nitrogen in oil through a certain oscillation period under the condition of constant temperature, and obtaining the original concentration of the dissolved gas through calculation by detecting the concentration of each component in the balance gas, wherein the method is incomplete degassing;
the film vacuum method is characterized in that a principle that gas with small molecular weight can pass through a film but oil cannot pass through the film due to the fact that the molecular volume difference between transformer oil and dissolved gas is utilized, a high polymer film is adopted to separate the oil and the gas, a gas sampling side is vacuumized, a positive pressure is applied to a sample oil side, and the dissolved gas permeates to a vacuum side through a pressure difference to complete collection;
the mechanical vacuum method is evolved from a mercury vacuum degassing method, and utilizes the characteristic that atmospheric pressure and negative pressure alternately apply force to a variable-diameter piston to replace an equivalent device of a mercury pump;
the method adopts a degassing mode combining a dissolution balance method and a mechanical vacuum method, heats sample oil to a certain temperature, keeps a constant temperature state, and repeatedly pushes and pulls an electric push-pull rod to form a vacuum and normal pressure alternate environment to obtain the separation gas.
According to the technical scheme, the monitoring gas separated from the gas separation module belongs to mixed trace gas, and the main components of the monitoring gas are hydrogen, carbon monoxide, methane, ethane, ethylene and acetylene.
According to the above technical solution, the gas analysis module mainly analyzes the obtained desorbed gas by a gas analysis method, and the gas analysis method mainly includes: gas chromatography and photoacoustic spectrometry;
the gas chromatography structurally comprises a gas path system, a column thermostat, a chromatographic column, a detector, a data processing system and the like, wherein mixed gas is brought into the thermostatic chromatographic column through carrier gas with a certain flow rate, each component gas flows out in sequence at a set flow rate within a specified time by utilizing the separation action of the chromatographic column, and the data analysis system analyzes and calculates the data waveform area of the detector to obtain the content of each gas component;
the principle of the method is that heat energy or infrared radiation of characteristic gas is converted into sound pressure signals, then the sound signals are converted into electric signals through a micro-sound detector, and the electric signals are amplified and input into a data display device to complete detection;
according to the practical application condition of the transformer, because the requirement of testing time is lower relative to the requirement of space, and the photoacoustic spectrometry is superior to gas chromatography in all aspects, the photoacoustic spectrometry is selected, and the automatic sampling and sample injection analysis is realized by adopting an electromagnetic valve, a vacuum pump, an air chamber, an MEMS (micro-electromechanical systems) electric modulation light source and the like in the design of an air path.
According to the technical scheme, when the gas analysis module analyzes the separated gas, the gas analysis module mainly adopts comparison experiment research and quantitative analysis, and the gas analysis module adopts a comparison experiment to analyze, compare and research data by collecting all test data in a certain time period.
According to the technical scheme, the data transmission module is used for transmitting the analyzed result information to the control terminal in a wired or wireless mode by combining a computer technology and a communication technology.
Compared with the prior art, the invention has the beneficial effects that:
1. the detection system is developed based on the advanced enhanced photoacoustic spectroscopy platform technology, has the characteristics of high sensitivity and quick response, can continuously monitor 9 fault gases and trace water on line, has a simple system structure, is maintenance-free, has no carrier gas, does not need frequent calibration and has no radiation source, high-precision measurement results enable the system to accurately identify potential faults, test data and diagnosis information can be timely transmitted in a wired and wireless mode, the safety and reliability of equipment operation are ensured, the regular maintenance mode of the equipment is changed into real-time monitoring and preventive detection or maintenance, and the occurrence of major power accidents is favorably reduced;
meanwhile, by adopting the two-stage absorption enhanced photoacoustic spectroscopy technology, the gas chromatographic monitor has the advantages of high sensitivity, low drift and continuous online monitoring, and effectively solves the problems that the traditional gas chromatographic monitor needs consumable carrier gas and standard gas, a chromatographic column is easy to age and cannot stably run for a long time.
2. When the photoacoustic cell is selected, the tubular gold-plated photoacoustic air chamber is adopted, so that the detector is isolated from gas, the pollution of oil gas to the detector is reduced to a certain degree, and the noise interference of a mobile phase is avoided.
3. Adopt contrast experiment research, quantitative analysis through contrastive analysis research module, be convenient for carry out analysis comparative research to data, and through the contrastive analysis to the experimental data, conveniently look for the deviation reason, redesign system oil circuit and gas circuit system.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.
In the drawings:
FIG. 1 is a block diagram of the detection system of the present invention;
FIG. 2 is a technical scheme of the gas analysis module of the present invention;
fig. 3 is a real object diagram of the transformer on-line monitoring port of the invention.
Detailed Description
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.
Example (b): as shown in fig. 1-3, the present invention provides a technical solution, a photoacoustic spectroscopy insulating oil dissolved gas detection system based on MEMS technology, including a sample oil sampling module, a light source photoacoustic cell selection module, a two-stage absorption enhancement module, a gas separation module, a gas analysis module, and a data transmission module;
the detection system irradiates a sample sealed in the photoacoustic cell through a modulated monochromatic light source, the sample absorbs light energy and is de-excited in a mode of releasing heat energy, the released heat energy enables the sample and surrounding media to generate periodic heating according to the modulation frequency of light, so that the media generate periodic pressure fluctuation, the pressure fluctuation is detected through a photoacoustic spectrum detector with extremely high sensitivity, and photoacoustic signals are obtained through amplification;
because each infrared active compound has a specific infrared absorption spectrum, the wavelength of monochromatic light is changed, and photoacoustic signals changing along with the wavelength can be detected, so that quantitative analysis of the compounds is realized.
Based on above-mentioned technical scheme, sample oil sampling module mainly acquires the sample oil in the transformer tank that needs to survey, and many-sided factors need be considered in the acquirement of sample oil: the method comprises the following steps of (1) fully considering the factors and combining with on-site investigation, selecting a transformer on-line monitoring port for sampling, wherein the positions of sampling ports of different types of transformers are different, and the positions of the sampling ports are shown in figure 3;
after the sample oil is detected and analyzed, the sample oil is processed in a mode of returning to an oil tank of the transformer.
Based on the technical scheme, the light source photoacoustic cell selection module uses a point-modulated MEMS infrared light source to replace the traditional mechanical chopper dimming mode when selecting the light source, and the MEMS infrared light source is mainly an infrared light source device based on a micro electro mechanical system manufacturing process;
when the photoacoustic cell is selected, the tubular gold-plated photoacoustic air chamber is mainly adopted, so that the detector is isolated from the gas, the pollution of oil gas to the detector is reduced, and the noise interference of a mobile phase is avoided.
Based on the technical scheme, when the light source photoacoustic cell selection module selects the MEMS infrared light source, the radiation spectrum distribution characteristic test is carried out on the MEMS infrared light source by adopting the SR5000 spectral radiometer, so that the radiation spectrum distribution characteristic and the temperature characteristic of the MEMS infrared light source are determined.
Based on the technical scheme, the double-stage absorption enhancement module adopts a double-stage absorption enhancement type photoacoustic spectroscopy technology, so that the equipment has high sensitivity, high reliability and high stability;
a double-stage absorption enhancement structure is adopted to isolate a gas sample from the photoacoustic detector, the total volume of the whole gas chamber is less than 3ML, most of infrared energy after passing through the first-stage analysis gas chamber is absorbed in the second-stage photoacoustic gas chamber, and gas generated after oil-gas separation does not contact with the detection element.
Based on the technical scheme, the gas separation module is mainly used for separating gas from oil to analyze dissolved gas components in the oil, and then the photoacoustic spectrometry is used for analyzing components and content, wherein the degassing mode comprises a dissolution equilibrium method, a thin film vacuum method and a mechanical vacuum method;
the dissolving balance method, also called mechanical oscillation method, reestablishes the balance between the dissolved gas and the high-purity nitrogen in the oil through a certain oscillation period under the condition of constant temperature, and obtains the original concentration of the dissolved gas through calculation by detecting the concentration of each component in the balance gas, and the method has the advantages of incomplete degassing: the operation mode is simple, the dissolution balance stability is fully utilized to separate gas, the repeatability is high, and the defects are as follows: the degassing rate is low, the concentration of some key gases after degassing is low, the requirement on the resolution of a gas detector is high, and the integral error is large;
the film vacuum method utilizes the principle that the molecular volume difference between transformer oil and dissolved gas is utilized, gas with small molecular weight can pass through the film and oil can not pass through, adopts high polymer film to separate oil and gas, and to the evacuation of gas sampling side, the positive pressure is exerted on the sample oil side, and the dissolved gas permeates to the vacuum side through pressure difference to finish the collection, the advantage: high efficiency, short degassing time and disadvantages: the requirement on the air tightness of the whole device is high due to large pressure difference, and the film is easy to damage and short in service life;
the mechanical vacuum method is evolved from a mercury vacuum degassing method, and utilizes the characteristic that atmospheric pressure and negative pressure alternately apply force to a variable-diameter piston to replace an equivalent device of a mercury pump, and has the advantages that: reach the full degasification effect, small, simple to use, safe and reliable, shortcoming: the degassing efficiency is low, and the time consumption is long;
the method adopts a degassing mode combining a dissolution balance method and a mechanical vacuum method, heats sample oil to a certain temperature, keeps a constant temperature state, and repeatedly pushes and pulls an electric push-pull rod to form a vacuum and normal pressure alternate environment to obtain the separation gas.
Based on the technical scheme, the monitoring gas separated from the gas separation module belongs to mixed trace gas, and the main components of the monitoring gas are hydrogen, carbon monoxide, methane, ethane, ethylene and acetylene.
Based on the technical scheme, the gas analysis module mainly analyzes the obtained desorbed gas by a gas analysis method, and the gas analysis method mainly comprises the following steps: gas chromatography and photoacoustic spectrometry;
the structure of the gas chromatography comprises a gas path system, a column thermostat, a chromatographic column, a detector, a data processing system and the like, mixed gas is brought into the thermostatic chromatographic column through carrier gas with a certain flow rate, and each component gas flows out in sequence at a set flow rate in a specified time by utilizing the separation action of the chromatographic column, and the data analysis system analyzes and calculates the data waveform area of the detector to obtain the content of each gas component, and has the advantages that: the analyzable gas has multiple types, large analyzable content range and defects: the time consumption is long, the data is unstable, the structure is complex, and the analysis is not accurate enough;
the photoacoustic spectrometry utilizes different air chambers and detectors to measure the content of each component in the mixed gas, mainly comprises infrared source, sample chamber, filter, light filter, detector, amplifier and data display device, and its principle is to change the heat energy or infrared radiation of characteristic gas into the sound pressure signal, and the rethread microsound detector converts the acoustic signal into the signal of telecommunication and through amplification processing again, inputs data display device and accomplishes the detection, the advantage: the response speed is fast, it is high to examine and examine the precision, stability is good, non-maintaining, longe-lived, the shortcoming: large one-time investment;
according to the practical application condition of the transformer, because the requirement of testing time is lower relative to the requirement of space, and the photoacoustic spectrometry is superior to gas chromatography in all aspects, the photoacoustic spectrometry is selected, and the automatic sampling and sample injection analysis is realized by adopting an electromagnetic valve, a vacuum pump, an air chamber, an MEMS (micro-electromechanical systems) electric modulation light source and the like in the design of an air path.
Based on the technical scheme, when the gas analysis module analyzes the separated gas, the gas analysis module mainly adopts comparison experiment research and quantitative analysis, and adopts comparison experiment to analyze and compare and research data by collecting all test data in a certain time period.
Based on the technical scheme, the data transmission module is used for transmitting the analyzed result information to the control terminal in a wired or wireless mode by combining a computer technology and a communication technology.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described above, or equivalents may be substituted for elements thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A photoacoustic spectroscopy insulating oil dissolved gas detection system based on MEMS technology is characterized in that: the device comprises a sample oil sampling module, a light source photoacoustic cell selection module, a two-stage absorption enhancement module, a gas separation module, a gas analysis module and a data transmission module;
the detection system irradiates a sample sealed in the photoacoustic cell through a modulated monochromatic light source, the sample absorbs light energy and is de-excited in a mode of releasing heat energy, the released heat energy enables the sample and surrounding media to generate periodic heating according to the modulation frequency of light, so that the media generate periodic pressure fluctuation, the pressure fluctuation is detected through a photoacoustic spectrum detector with extremely high sensitivity, and photoacoustic signals are obtained through amplification;
because each infrared active compound has a specific infrared absorption spectrum, the wavelength of monochromatic light is changed, and photoacoustic signals changing along with the wavelength can be detected, so that quantitative analysis of the compounds is realized.
2. A photoacoustic spectroscopy-based photoacoustic oil-dissolved gas detection system according to claim 1, wherein: the sample oil sampling module mainly acquires sample oil in a transformer oil tank to be detected, and the acquisition of the sample oil needs to consider various factors: the method comprises the following steps of (1) fully considering the factors and combining with on-site investigation, selecting a transformer on-line monitoring port for sampling, wherein the positions of sampling ports of different types of transformers are different;
after the sample oil is detected and analyzed, the sample oil is processed in a mode of returning to an oil tank of the transformer.
3. A photoacoustic spectroscopy-based photoacoustic oil-dissolved gas detection system according to claim 1, wherein: the light source photoacoustic cell selection module is characterized in that when a light source is selected, a point-modulated MEMS infrared light source is used for replacing a traditional mechanical chopper dimming mode, and the MEMS infrared light source is mainly an infrared light source device based on a micro-electro-mechanical system manufacturing process;
when the photoacoustic cell is selected, the tubular gold-plated photoacoustic air chamber is mainly adopted, so that the detector is isolated from the gas, the pollution of oil gas to the detector is reduced, and the noise interference of a mobile phase is avoided.
4. A photoacoustic spectroscopy insulated oil-dissolved gas detection system based on MEMS technology as claimed in claim 3, characterized in that: when the light source photoacoustic cell selection module selects the MEMS infrared light source, the radiation spectrum distribution characteristic test is carried out on the MEMS infrared light source by adopting the SR5000 spectrum radiometer, so that the radiation spectrum distribution characteristic and the temperature characteristic of the MEMS infrared light source are determined.
5. A photoacoustic spectroscopy-based photoacoustic oil-dissolved gas detection system according to claim 1, wherein: the double-stage absorption enhancement module adopts a double-stage absorption enhancement type photoacoustic spectroscopy technology, so that the equipment has high sensitivity, reliability and stability;
a double-stage absorption enhancement structure is adopted to isolate a gas sample from the photoacoustic detector, the total volume of the whole gas chamber is less than 3ML, most of infrared energy after passing through the first-stage analysis gas chamber is absorbed in the second-stage photoacoustic gas chamber, and gas generated after oil-gas separation does not contact with the detection element.
6. A photoacoustic spectroscopy insulated oil-dissolved gas detection system according to claim 1 based on MEMS technology, characterized in that: the gas separation module is mainly used for analyzing dissolved gas components in oil by separating gas from the oil, and then the components and the content are analyzed by adopting a photoacoustic spectrometry, wherein the degassing mode comprises a dissolution equilibrium method, a thin film vacuum method and a mechanical vacuum method;
the method adopts a degassing mode combining a dissolution balance method and a mechanical vacuum method, heats sample oil to a certain temperature, keeps a constant temperature state, and repeatedly pushes and pulls an electric push-pull rod to form a vacuum and normal pressure alternate environment to obtain the separation gas.
7. The photoacoustic spectroscopy insulating oil-dissolved gas detection system according to claim 6, wherein: the monitoring gas separated from the gas separation module belongs to mixed trace gas, and the main components of the monitoring gas are hydrogen, carbon monoxide, methane, ethane, ethylene and acetylene.
8. A photoacoustic spectroscopy insulated oil-dissolved gas detection system according to claim 1 based on MEMS technology, characterized in that: the gas analysis module mainly analyzes the obtained desorbed gas by a gas analysis method, and the gas analysis method mainly comprises the following steps: gas chromatography and photoacoustic spectrometry;
according to the practical application condition of the transformer, because the requirement of testing time is lower relative to the requirement of space, and the photoacoustic spectrometry is superior to gas chromatography in all aspects, the photoacoustic spectrometry is selected, and the automatic sampling and sample injection analysis is realized by adopting an electromagnetic valve, a vacuum pump, an air chamber, an MEMS (micro-electromechanical systems) electric modulation light source and the like in the design of an air path.
9. A photoacoustic spectroscopy-based photoacoustic oil-dissolved gas detection system according to claim 8, wherein: when the gas analysis module analyzes the separated gas, the gas analysis module mainly adopts contrast experiment research and quantitative analysis, and the gas analysis module adopts a contrast experiment to analyze, compare and research data by collecting all test data in a certain time period.
10. A photoacoustic spectroscopy-based photoacoustic oil-dissolved gas detection system according to claim 1, wherein: the data transmission module is used for transmitting the analyzed result information to the control terminal in a wired or wireless mode by combining a computer technology and a communication technology.
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