WO2022151880A1

WO2022151880A1 - System and method for detecting gas in transformer oil, and system for detecting fault in transformer

Info

Publication number: WO2022151880A1
Application number: PCT/CN2021/137011
Authority: WO
Inventors: 李林; 杨颖�; 王杰; 黄志华; 肖黎亚; 刘翊; 莫洪波; 陈皓; 黄贵励; 蒋小林; 谢谨; 吴晗; 刘海龙
Original assignee: 株洲国创轨道科技有限公司
Priority date: 2021-01-14
Filing date: 2021-12-10
Publication date: 2022-07-21
Also published as: CN112881948A

Abstract

A system for detecting gas in transformer oil, a detection method, and a system for detecting a fault in a transformer. The system for detecting gas comprises an oil-gas separation unit, a gas flow path unit, a gas separation unit, and a gas detection unit; the oil-gas separation unit comprises an oil-gas separator (11), and a gas chamber (3); the gas flow path unit comprises a gas pump (1), a gas path pipe (2), and the gas chamber (3); the gas chamber (3) is mounted on the oil-gas separator (11) and is used for collecting gas separated by the oil-gas separator (11); the gas path pipe (2) is used for sequentially connecting the gas pump (1), the gas chamber (3), the gas separation unit, and the gas detection unit; the gas pump (1) is used for supplying carrier gas so as to push mixed characteristic gas in the gas chamber (3) into the gas separation unit; the gas separation unit comprises a gas chromatography chip (4) and is used for separating the mixed characteristic gas; and the gas detection unit is used for detecting the type and content of the separated characteristic gas. The system has the advantages of real-time detection, high detection efficiency, pollution prevention, high detection accuracy, and the like.

Description

System, method and transformer fault detection system for detecting gas in transformer oil

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on the Chinese patent application with the application date of "2021-01-14", the application number of "202110048437.2", and the invention-creation title of "system, method and transformer fault detection system for detecting gas in transformer oil", and claim its priority, the full text of the Chinese patent application is incorporated herein by reference as a part of the present application.

【Technical field】

The invention mainly relates to the technical field of transformer oil, in particular to a system and method for detecting gas in transformer oil and a transformer fault detection system.

【Background technique】

Electric locomotives are the operating carrier of the rail transit industry and an inseparable and important part of China's economic artery. The power of the electric locomotive comes from the 25KV voltage of the external catenary. The high voltage is converted into a variety of low voltages (such as 970V voltage) through the transformer, thereby providing effective and usable energy for the traction motor of the whole vehicle. During the normal running of an electric locomotive, as an important part of the power plant, the safe and healthy state of the transformer operation is very important. The interior of the electric locomotive transformer is filled with transformer oil, which plays three roles of heat dissipation, insulation and arc suppression. During the normal operation of the transformer, the transformer oil will gradually age and decompose, producing less organic gases such as low molecular hydrocarbons, and inorganic gases such as carbon monoxide and carbon dioxide. When the transformer fails, the hydrocarbon organic gas or carbon inorganic gas produced by the decomposition of transformer oil will increase significantly, and the composition and corresponding content of the characteristic gas are closely related to the type and severity of the transformer fault.

At present, the inspection of transformer oil still relies on manual sampling and inspection of oil chromatography technology. This method takes a long time and has high maintenance costs. At the same time, there are also problems such as repeated pollution to transformer oil. Speed up its internal wear.

In addition, there are also technologies for monitoring the internal oil state of transformers, such as electrochemical sensors, laser monitoring technology, and ultrasonic monitoring technology. Although the electrochemical sensor monitoring method is fast, its life expectancy in harsh environments is not long; laser detection and Ultrasonic monitoring technology cannot avoid the problem of cross-interference caused by mixed gases, and the detection accuracy is limited.

[Content of the invention]

The technical problem to be solved by the present invention is: in view of the existing problems in the prior art, the present invention provides a real-time detection, high detection efficiency, and pollution-avoiding transformer oil gas detection system, method, and transformer fault detection system.

In order to solve the above-mentioned technical problems, the technical scheme proposed by the present invention is:

A system for detecting gas in transformer oil, comprising an oil and gas separation unit, a gas flow path unit, a gas separation unit and a gas detection unit;

The oil-gas separation unit includes an oil-gas separator and an air chamber, and the oil-liquid inlet and the oil-liquid outlet of the oil-gas separator are both connected to the electric locomotive transformer;

The gas flow path unit includes an air pump, an air path pipeline and an air chamber; the air chamber is installed on the oil and gas separator, and is used to collect the gas separated by the oil and gas separator; the air path pipeline is used to connect the air pump, the air chamber , the gas separation unit and the gas detection unit are connected in sequence; the gas pump is used to provide a carrier gas to push the mixed characteristic gas in the gas chamber into the gas separation unit;

The gas separation unit includes a gas chromatography chip, and the surface of the gas flow pipe of the gas chromatography chip is coated with a stationary phase coating, which is used for repeated adsorption and desorption processes with the mixed characteristic gas to separate the mixed characteristic gas;

The gas detection unit includes a surface acoustic wave gas sensor for detecting the type and content of the separated characteristic gas.

As a further improvement of the above technical solution:

The gas separation unit further includes a heating module for heating the gas chromatography chip to maintain it within a rated temperature range.

A cooling sheet is also included for maintaining the surface acoustic wave gas sensor within a rated temperature range.

The present invention also discloses a transformer fault detection system, comprising an acquisition unit, a fault determination unit and the above-mentioned system for detecting gas in transformer oil, wherein the acquisition unit is respectively connected with the acquisition unit and the gas detection system, The type and content of the characteristic gas detected by the gas detection system are collected, and the fault determination unit is used for judging the fault of the transformer according to the type and content of the characteristic gas.

The present invention further discloses a gas detection method based on the above-mentioned system for detecting gas in transformer oil, comprising the steps of:

1) Extract the transformer oil inside the transformer into the oil and gas separator through the oil inlet, separate the characteristic gas in the transformer oil through the oil and gas separator, and then discharge the transformer oil into the transformer through the oil outlet;

2) The air chamber is communicated with the oil and gas separator, and the characteristic gas separated from the transformer oil enters the air chamber; the air pump extracts air to form a carrier gas, which is mixed with the characteristic gas inside the air chamber, and pushes the characteristic gas to be delivered to the gas. in the separation unit;

3) The stationary phase coating applied on the surface of the gas flow duct of the gas separation unit and the mixed characteristic gas undergo repeated adsorption and desorption processes to separate the mixed characteristic gas;

4) The surface acoustic wave gas sensor detects the type and content of the separated characteristic gas.

As a further improvement of the above technical solution:

In step 3), the gas chromatographic chip has a long and narrow gas flow pipeline filled with micro-columns inside, and the stationary phase coating coated on the surface of the gas flow pipeline undergoes repeated adsorption and desorption processes with the mixed characteristic gas;

Due to the different distribution coefficients between different characteristic gases and the stationary phase coating, the retention capacity of the stationary phase coating during the gas flow process is different, and finally each characteristic gas comes out in sequence at the outlet of the gas flow pipe, thereby realizing the mixing of characteristic gases. separation between.

In step 4), the surface of the surface acoustic wave gas sensor is maintained at a preset temperature and is lower than the temperature of the characteristic gas flowing out of the gas separation unit to form a temperature gradient, the temperature gradient makes the characteristic gas enter the interior of the surface acoustic wave gas sensor chamber, It is rapidly condensed and adsorbed on the surface of the surface acoustic wave gas sensor, and the propagation characteristics of the surface acoustic wave change, which is expressed by the change of the oscillation frequency; The effect passes through the IDT and the impedance matching circuit, and is transmitted to the antenna to form an echo electromagnetic wave.

Before step 1), also include the pre-boot process:

Perform corresponding temperature feedback and control on the gas chromatography chip and the surface acoustic wave gas sensor to keep it within the corresponding rated temperature range for a preset time;

The system transmits electromagnetic wave signals to the surface acoustic wave gas sensor. After the antenna of the surface acoustic wave gas sensor receives the radio frequency signal, the surface acoustic wave gas sensor converts the radio frequency signal into the surface acoustic wave through the inverse piezoelectric effect; The surface of the piezoelectric substrate propagates, and after encountering the reflection grid array, reflection occurs, the reflected signals are superimposed, and the radio frequency electrical signal is excited again, which is converted into an echo electromagnetic wave signal by the IDT through the piezoelectric effect; the antenna of the system converts the echo electromagnetic wave The signal is received, and a stable signal baseline under initial conditions is obtained on the screen.

Compared with the prior art, the advantages of the present invention are:

1) Compared with manual regular maintenance and detection, the system can realize real-time monitoring of trains whether during outage or during operation, avoiding problems such as human measurement errors, internal pollution caused by improper human operation, and long maintenance time. , and the detection efficiency is high.

2) The present invention can monitor the early development stage of transformer failure. By using the dissolved gas separated from the oil, combined with the surface acoustic wave and gas chromatography on-line detection technology, the statistical analysis of the change trend of the type and content of the dissolved gas is carried out. Before the transformer oil cracks a large amount of gas, it can be transmitted in time. Signal, feedback problems, report potential safety hazards of transformers.

3) The present invention combines three technologies: MEMS technology, gas chromatography technology and surface acoustic wave sensing technology. Using MEMS technology, the gas chromatography chip and the surface acoustic wave gas sensor can be assembled and integrated to compress the device volume and energy consumption. The use of gas chromatography to separate the mixed gas can effectively avoid the problem of cross-interference caused by the mixed gas to the detector and improve the detection accuracy; the use of surface acoustic wave sensing technology for gas detection and signal transmission Metal oxide semiconductor gas sensor does not require high temperature detection environment (such as 600 ℃), which is safer in oil environment; on the other hand, signal transmission can be through electromagnetic wave signal, and one collector can collect signals corresponding to multiple SAW gas sensors, In complex equipment environments, it is easy to install and monitor comprehensively.

4) The present invention can be installed on the transformer, and it can not only judge in real time that the transformer is in normal operation, early failure stage, mid-failure stage, etc. under the condition of high-speed operation of electric locomotives, but also can perform multi-point detection and feedback the detection data to the cloud system. , to lay a good data foundation for the prediction and analysis of the healthy life of electric locomotive transformers in the later period. The core devices are μGC chip and SAW gas sensor, both of which can be developed using MEMS technology and integrated into one. The μGC chip adopts a semi-filled serpentine layout flow channel structure, which has the advantages of large specific surface area, short mass transfer distance, and small gas dispersion. Save heating power consumption.

【Description of drawings】

FIG. 1 is a schematic structural diagram of an embodiment of the present invention.

FIG. 2 is a diagram of an embodiment of the device controller of the present invention in a specific application.

The symbols in the figure indicate: 1, air pump; 2, gas pipeline; 3, air chamber; 4, gas chromatography chip; 5, surface acoustic wave gas sensor; 6, antenna; 7, collector; 8, equipment controller; 9 , oil outlet; 10, oil inlet; 11, oil and gas separator.

【Detailed ways】

The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

As shown in Figure 1, the system for detecting gas in transformer oil of the present embodiment includes an oil and gas separation unit, a gas flow path unit, a gas separation unit and a gas detection unit; the oil and gas separation unit includes an oil and gas separator 11 and a gas chamber 3, The oil inlet 10 and the oil outlet 9 of the oil and gas separator 11 both extend into the interior of the transformer of the electric locomotive for the collection and discharge of transformer oil; the gas flow path unit includes an air pump 1, an air path pipeline 2 and an air chamber 3; the air chamber 3 is installed on the oil and gas separator 11 to collect the gas separated by the oil and gas separator 11; the gas pipeline 2 is used to connect the gas pump 1, the gas chamber 3, the gas separation unit and the gas detection unit in sequence; the gas pump 1 is used to provide a carrier. gas, to push the mixed characteristic gas in the gas chamber 3 into the gas separation unit; the gas separation unit is used to separate the mixed characteristic gas; the gas detection unit is used to detect the type and content of the separated characteristic gas.

In a specific embodiment, the gas separation unit includes a gas chromatography (Micro Gas Chromatography, μGC) chip, referred to as a μGC chip, and the inside of the μGC chip has a long and narrow airflow duct filled with micro-columns, and the surface of the airflow duct is coated with a stationary phase. Coating for repeated adsorption and desorption processes with mixed characteristic gases. Due to the difference in the intermolecular forces between characteristic gases of different molecular weights and the stationary phase coating, as the carrier gas continuously pushes the flow of the characteristic gases, the characteristic gases will eventually separate from each other on the time axis. In addition, a heating module (such as a resistance heater) and a temperature measurement module (such as a temperature sensor) are integrated on the back of the μGC chip to perform closed-loop heating control of the μGC chip to maintain it within the rated temperature range required for characteristic gas separation Inside.

In a specific embodiment, the gas detection unit includes a surface acoustic wave (Surface Acoustic Wave, SAW) gas sensor, referred to as a SAW gas sensor. SAW gas sensors are resonator-type high-frequency devices with low time delay, high speed of sound, high reliability, etc., and can better adapt to high voltage, strong electromagnetic, severe vibration and airtight environments of electric locomotives; resonator-type SAW gas sensors It usually includes an Interdigital Transducer (IDT) and two sets of reflection grids. The reflection grids are symmetrically arranged on both sides of the IDT in the center of the substrate. At the same time, the SAW gas sensor is connected to an impedance matching network and an antenna 6 for Transmission of high frequency signals. The back of the SAW gas sensor is provided with a cooling module (such as a cooling sheet) and a temperature measuring module, which are used to maintain the surface acoustic wave gas sensor 5 within the rated temperature range through closed-loop control. Since the above μGC chip has a certain temperature for gas separation, while the SAW gas sensor uses a refrigeration chip to maintain a lower constant temperature and normal temperature state, the two have a certain temperature gradient. After the characteristic gas is separated from the μGC chip, it will be condensed on the surface of the SAW gas sensor in turn. The change of the surface acoustic wave propagation characteristics caused by the condensation of different characteristic gases on the surface of the SAW gas sensor leads to the change of the vibration frequency of the SAW gas sensor. Through the calibration and monitoring of the frequency change, the type and content of the relevant characteristic gases can be analyzed.

The invention can be assembled on the transformer, perform online detection according to a fixed time period, and accumulate long-term data at the same time, which can be used for the analysis and prediction of the transformer's health state. Integrated assembly in one. The μGC chip adopts a semi-filled serpentine layout flow channel structure, which has the advantages of large specific surface area, short mass transfer distance, and small gas dispersion. Save heating power consumption.

The present invention also discloses a transformer fault detection system, which includes a collection unit (such as a collector 7), a fault determination unit (such as the equipment controller 8 in FIG. 1 and FIG. The gas system, the acquisition unit is respectively connected with the acquisition unit and the gas detection system, and is used to collect the type and content of the characteristic gas detected by the gas detection system. The fault determination unit is used to determine the fault of the transformer according to the type and content of the characteristic gas. , and display related signals and states at the same time.

Specifically, the collector 7 receives the radio frequency signal generated by the SAW gas sensor through the antenna 6 in real time, and after signal demodulation and processing, obtains graphic and digital information such as the peak time and peak shape state of each characteristic gas, and displays it on the display. middle. Finally, the characteristic gas data is analyzed by the three ratio method and the gas production rate method, so as to judge and monitor the transformer oil status in real time, and obtain the monitoring conclusions such as normal internal health, high temperature and overheating, arc discharge, arc discharge and overheating.

In a specific embodiment, the device controller 8 includes a microprocessor, a temperature control module, a valve control module, a liquid crystal display module, a status indication module and a key command module, a temperature control module, a valve control module, a liquid crystal display module, a status indication The module and the key command module are connected with the microprocessor; the microprocessor receives the signal through the collector 7 and analyzes the signal; the liquid crystal display module displays the analysis result in real time, and the status indicator module briefly indicates the operating status of the transformer. The temperature control module is respectively connected with the μGC chip and the SAW gas sensor; the valve control module respectively controls the on-off of the valve between the oil and gas separator 11 and the gas chamber 3, so as to control the oil and gas paths such as oil sample extraction and exhaust.

The gas detection system and the transformer fault detection system of the present invention can monitor the state of the transformer oil in real time, and have the following technical effects:

1) Compared with manual regular maintenance and detection, the system can realize real-time monitoring of trains whether during outage or during operation, avoiding problems such as human measurement errors, internal pollution caused by improper human operation, and long maintenance time. .

2) The present invention can monitor the early development stage of transformer failure. By using the dissolved gas separated from the oil, combined with the surface acoustic wave and gas chromatography on-line detection technology, a statistical analysis of the change trend of the type and content of the dissolved gas is carried out. Before the transformer oil cracks a large amount of gas, it can be transmitted in time. Signal, feedback problems, report potential safety hazards of transformers.

3) The present invention combines three technologies: MEMS technology, gas chromatography technology and surface acoustic wave sensing technology. Using the MEMS technology, the gas chromatography chip 4 and the surface acoustic wave gas sensor 5 can be assembled and integrated into one, thereby compressing the device volume and energy consumption. The use of gas chromatography to separate the mixed gas can effectively avoid the problem of cross-interference caused by the mixed gas to the detector; the use of surface acoustic wave sensing technology for gas detection and signal transmission, on the one hand, compared with commonly used metal oxide semiconductors The gas sensor does not require a high temperature detection environment (such as 600°C), and is safer in an oil environment; on the other hand, the signal transmission can be through electromagnetic wave signals, and one collector 7 can collect signals corresponding to multiple SAW gas sensors. In the equipment environment, the installation is convenient and the monitoring is comprehensive.

The present invention also discloses a gas detection method based on the above-mentioned system for detecting gas in transformer oil, comprising the steps of:

1) Extract the transformer oil inside the transformer into the oil and gas separator 11 through the oil inlet 10, separate the characteristic gas in the transformer oil through the oil and gas separator 11, and then discharge the transformer oil into the transformer through the oil outlet 9 ;

2) The air chamber 3 is communicated with the oil and gas separator 11, and the characteristic gas separated in the transformer oil enters the air chamber 3; the air pump 1 extracts air to form a carrier gas, which is mixed with the characteristic gas inside the air chamber 3, and promotes the characteristic gas. delivered to the gas separation unit;

3) The gas separation unit separates each mixed characteristic gas;

4) The gas detection unit detects the type and content of the separated characteristic gas.

The above invention will be further described below in conjunction with a specific embodiment:

1. Pre-start of the instrument: The equipment controller 8 starts the temperature control module, and performs corresponding temperature feedback and control on the μGC chip and SAW gas sensor. The temperature control adopts the fuzzy PID algorithm for negative feedback adjustment, and the control accuracy reaches ±0.1 °C; After the chip and the SAW gas sensor reach the normal working temperature, maintain a constant temperature for 5 minutes, and ensure that the internal coating of the μGC chip reaches the rated temperature through a period of heat conduction, and the substrate surface of the SAW gas sensor reaches the rated temperature;

At the same time, the collector 7 is started to continuously transmit electromagnetic wave signals to the SAW gas sensor; after the antenna 6 receives the radio frequency signal, the SAW gas sensor converts the radio frequency signal into SAW through the inverse piezoelectric effect; the SAW follows the surface of the piezoelectric substrate Propagation, reflection occurs after encountering the reflection grid array, the reflected signals are superimposed, and the radio frequency electrical signal is excited again, which is converted into an echo electromagnetic wave signal by the IDT through the piezoelectric effect; the antenna 6 sends the echo electromagnetic wave signal to the collector 7, Ultimately the process yields a stable signal baseline under initial conditions.

2. Extracting oil samples: the oil and gas separator 11 starts the oil inlet 10, extracts the transformer oil inside the transformer, and enters the oil and gas separator 11. At the same time, the valve control module of the equipment controller 8 closes the valve connecting the upper end of the oil-gas separator 11 and the air chamber 3 to prevent the oil from entering the air chamber 3 .

3. Oil and gas separation: the extracted oil enters the oil and gas separator 11, and under the uniform stirring of the stirring motor, the vacuum inside the separator is gradually extracted; and then the dissolved gas in the transformer oil is separated by the filter element. This separation process for about 10min. Afterwards, the valve control module of the equipment controller 8 opens the valve connecting the upper end of the oil-gas separator 11 and the gas chamber 3 , and the released gas reaches the gas chamber 3 . Next, the treated transformer oil is discharged into the transformer through the oil outlet 9 .

4. Air supply by air pump 1: Air pump 1 is started, and the air is drawn into the air pipeline 2; the air passes through the gas filter to form a pure carrier gas, which is mixed with the characteristic gas in the air chamber 3, and then pushes the characteristic gas to continue to advance.

5. Gas separation: driven by the carrier gas, the characteristic gas enters the μGC chip. Inside the μGC chip is a long and narrow gas flow channel filled with micro-columns. The surface of the micro-channel is coated with a stationary phase coating with targeted separation performance, which undergoes repeated adsorption and desorption processes with characteristic gases. The distribution coefficients between different characteristic gases and stationary phase coatings are different, and the retention capacity of the coatings is different. For example, the stronger the coating is to retain the characteristic gas, the later the characteristic gas will come out at the exit of the μGC chip. Finally, each characteristic gas comes out sequentially at the outlet of the μGC chip and enters the SAW gas sensor.

6. Gas detection: After the μGC chip separation treatment, the characteristic gas has a higher temperature, and the SAW gas sensor maintains a lower surface temperature due to the action of the cooling chip, and the temperature gradient makes the characteristic gas enter the SAW gas sensor chamber. , which is rapidly condensed and adsorbed on the surface of the SAW gas sensor, and the SAW gas sensor changes the propagation characteristics of the surface acoustic wave, which is expressed by the change of the oscillation frequency. The frequency changes of the sound waves on the surface of the substrate caused by different characteristic gases are transmitted to the antenna 6 through the IDT and impedance matching circuit through the piezoelectric effect to form echo electromagnetic waves, which are received by the collector 7 .

7. Data processing and state analysis: The collector 7 demodulates the received signal to form a chromatographic curve with qualitative and quantitative analysis of characteristic gases, which is the original data curve formed by continuously detecting the outflow concentration of components. The corresponding characteristic gas is judged according to the retention time value of the chromatographic peak in the curve, and the content of the characteristic gas is judged according to the peak area and peak height of the chromatographic peak. Then, according to the three-ratio method, the characteristic three-ratio values of the five gases of methane, ethane, ethylene, acetylene, and hydrogen are calculated, and the calculated results are compared and analyzed with the recommended standard of the power industry DL/T 722-2014. Find out if the transformer has failed, and what kind of failure (local overheating, arcing, etc.).

The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions that belong to the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those skilled in the art, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

A system for detecting gas in transformer oil, characterized in that it comprises an oil and gas separation unit, a gas flow path unit, a gas separation unit and a gas detection unit;

The oil-gas separation unit comprises an oil-gas separator (11) and an air chamber (3), and the oil-liquid inlet (10) and the oil-liquid outlet (9) of the oil-gas separator (11) are both connected to the transformer of the electric locomotive;

The gas flow path unit comprises an air pump (1), a gas path pipeline (2) and an air chamber (3); the air chamber (3) is installed on the oil and gas separator (11) and is used for collecting the oil and gas separator ( 11) Separated gas; the gas pipeline (2) is used to connect the gas pump (1), the gas chamber (3), the gas separation unit and the gas detection unit in sequence; the gas pump (1) is used to provide a carrier gas, to push the mixed characteristic gas in the gas chamber (3) into the gas separation unit;

The gas separation unit comprises a gas chromatography chip (4), the surface of the gas flow pipe of the gas chromatography chip (4) is coated with a stationary phase coating for repeated adsorption and desorption processes with the mixed characteristic gas to separate the mixed characteristic gas;

The gas detection unit includes a surface acoustic wave gas sensor (5) for detecting the type and content of the separated characteristic gas.
The system for detecting gas in transformer oil according to claim 1, characterized in that the gas separation unit further comprises a heating module for heating the gas chromatography chip (4) so as to keep it at a temperature within the rated temperature range.
The system for detecting gas in transformer oil according to claim 1, characterized in that it further comprises a cooling chip, which is used to maintain the surface acoustic wave gas sensor (5) within a rated temperature range.
A transformer fault detection system, characterized in that it comprises an acquisition unit, a fault determination unit and the system for detecting gas in transformer oil according to claim 1, 2 or 3, wherein the acquisition unit is respectively connected with the acquisition unit. It is connected to the gas detection system and is used to collect the type and content of the characteristic gas detected by the gas detection system. The fault determination unit is used to determine the fault of the transformer according to the type and content of the characteristic gas.
A gas detection method based on the system for detecting gas in transformer oil according to any one of claims 1 to 3, characterized in that it comprises the steps of:

1) Extract the transformer oil inside the transformer into the oil and gas separator (11) through the oil inlet (10), separate the characteristic gas in the transformer oil through the oil and gas separator (11), and then pass the transformer oil through the oil outlet (9) Discharge into the transformer;

2) The air chamber (3) is communicated with the oil and gas separator (11), and the characteristic gas separated from the transformer oil enters the air chamber (3); the air pump (1) extracts air to form a carrier gas, which is connected with the air chamber (3). ) is mixed with the characteristic gas inside, and pushes the characteristic gas to be delivered to the gas separation unit;

3) The stationary phase coating applied on the surface of the gas flow duct of the gas separation unit and the mixed characteristic gas undergo repeated adsorption and desorption processes to separate the mixed characteristic gas;

4) The surface acoustic wave gas sensor (5) detects the type and content of the separated characteristic gas.
The gas detection method according to claim 5, characterized in that, in step 3), the gas chromatographic chip (4) has a narrow and long airflow duct filled with micro-columns inside, and the surface of the airflow duct is coated with a stationary phase Coating, repeated adsorption and desorption process with mixed characteristic gas;

Due to the different distribution coefficients between different characteristic gases and the stationary phase coating, the retention capacity of the stationary phase coating is different, so that each characteristic gas at the outlet of the gas flow pipe comes out in sequence, thereby realizing the separation of each characteristic gas.
The gas detection method according to claim 6, characterized in that, in step 4), the surface of the surface acoustic wave gas sensor (5) is kept at a preset temperature and is lower than the temperature of the characteristic gas to form a temperature gradient, the temperature gradient being such that The characteristic gas enters the chamber of the surface acoustic wave gas sensor (5), and is rapidly condensed and adsorbed on the surface of the surface acoustic wave gas sensor (5), so that the propagation characteristics of the surface acoustic wave change, which is manifested by the change of the oscillation frequency. ; The frequency change of the sound wave on the surface of the substrate caused by the gas with different characteristics is transmitted to the antenna (6) through the piezoelectric effect through the IDT and the impedance matching circuit to form an echo electromagnetic wave.
The gas detection method according to claim 7, characterized in that, before step 1), it also includes a pre-start process:

Corresponding temperature feedback and control are performed on the gas chromatography chip (4) and the surface acoustic wave gas sensor (5), so that they are maintained within the corresponding rated temperature range and maintained for a preset time;

The electromagnetic wave signal is transmitted to the surface acoustic wave gas sensor (5), and after the antenna (6) of the surface acoustic wave gas sensor (5) receives the radio frequency signal, the surface acoustic wave gas sensor (5) transmits the radio frequency signal through the inverse piezoelectric effect Converted to surface acoustic wave; the surface acoustic wave propagates along the surface of the piezoelectric substrate, and after encountering the reflection grid array, it is reflected, the reflected signals are superimposed, and the radio frequency electrical signal is excited again, and is converted into a return signal by the IDT through the piezoelectric effect. wave electromagnetic wave signal; the antenna (6) sends back the echo electromagnetic wave signal to obtain a stable signal baseline under the initial condition.