Device and method for detecting dissolved gas and gas content in transformer oil

Abstract

The invention discloses a device and a method for detecting dissolved gas and gas content in transformer oil, belongs to the technical field of power equipment state monitoring, and solves the problem of how to improve the detection efficiency of the dissolved gas and the gas content in the transformer oil. The device comprises a valve, a peristaltic pump, a flowmeter, an oil-gas membrane separation module, a mass spectrometry detection module, a low-concentration calibration mixed gas steel cylinder and a high-concentration calibration mixed gas steel cylinder, according to the method, the content of the target gas in the gas phase is analyzed by using the mass spectrometer and combining peak interference calibration, and then the concentration of each dissolved gas in the oil sample is calculated through reverse inference of the Henry law, so that the detection efficiency is greatly improved, and rapid, online and accurate monitoring of the multiple dissolved gases and the gas content in the transformer oil is realized; the method is suitable for transformer fault diagnosis and sealing state evaluation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power equipment state monitoring, and relates to a device and method for detecting dissolved gas and gas content in transformer oil. BACKGROUND

[0002] Oil-immersed transformers are core equipment of power systems, which use transformer oil as insulation and cooling medium to ensure safe operation of the equipment. During operation, transformer oil will deteriorate due to insulation faults (such as aging, discharge, etc.), producing characteristic gases such as acetylene (C2H2), methane (CH4), and hydrogen (H2). The concentration of these gases is directly related to the type and severity of the fault.

[0003] Online monitoring of dissolved gas in transformer oil realizes effective online monitoring of the internal operating state of oil-immersed transformers through monitoring and analysis of dissolved gas in insulating oil, which can timely discover and diagnose internal faults, thereby ensuring safe and stable operation of the transformer. The national standard "Guidelines for Transformer Oil Maintenance and Management" (GB / T 14542-2017) has specific requirements for the gas content index of transformers and reactors of different voltage levels after hot oil circulation and during operation.

[0004] The main working process of the current online monitoring device for dissolved gas in oil based on chromatography or photoacoustic spectroscopy is to separate the gas dissolved in the oil first, and then monitor and analyze the separated gas. Due to the inherent working principle limitation of gas separation and detection technology, the single monitoring period is more than 1h, which leads to the existing online monitoring device gradually difficult to meet the rapid monitoring demand, especially for the large oil-filled equipment serving extra-high voltage power transmission and transformation with fast fault development speed. For example, chromatography needs to complete a complex separation process, and the single detection period is usually more than 1h. The photoacoustic spectroscopy has a long detection period of more than 40 minutes due to low gas separation efficiency, which cannot realize rapid response. In addition, the field operation shows that the online monitoring device for dissolved gas in oil often has false negatives, false positives and other situations due to equipment aging and other reasons during long-term operation, which leads to the transformer damage due to the failure to repair the transformer in time, or unnecessary shutdown and repair. Therefore, it is necessary to calibrate and analyze the accuracy of the online monitoring device for dissolved gas. The main process is to configure oil samples with different contents, connect the online monitoring device to be calibrated with the inlet and outlet of the oil sample tank, detect the oil sample, manually sample, and use the laboratory insulating oil chromatograph to detect the results. The detection results of the laboratory chromatograph are used as reference values, the detection results of the online monitoring device are compared with the reference values, and the detection error of the monitoring device is evaluated. Since the detection period of the online monitoring device is generally 2h, and some even 4h, the repetitive test needs to be detected for 6 times, and the calibration of low, medium and high standard oil samples needs to be carried out, which leads to a long time-consuming of the whole calibration process, and the low work efficiency of manual sampling and detection. In addition, the standard oil sample prepared in the laboratory is greatly affected by temperature, pressure and transportation bump, and the gas concentration is easy to change, which leads to the decrease of calibration accuracy.

[0005] The invention patent document with the application publication number CN119104667A discloses a transformer oil chromatography online detection device and method. Different concentrations of standard oil samples are pre-configured and stored in specific storage containers. The corresponding valves are controlled to realize automatic switching sampling of transformer standard oil samples, and then data comparison and verification of online monitoring devices and offline monitoring devices are realized. However, it is still necessary to configure standard oil samples, and then perform calibration operation on the online device on site. The invention patent document with the application publication number CN111239304A discloses an insulating oil gas component content reference oil sample configuration system, which can configure high, medium and low concentration reference oil samples. The reference oil sample configuration system can configure target reference oil sample concentrations that meet the calibration requirements of multiple instruments. However, there are disadvantages such as large equipment size, difficulty in carrying, and inability to recycle calibration oil samples. The existing transformer oil dissolved gas online monitoring device field calibration device and method based on standard oil samples have the following disadvantages: first, the laboratory-prepared standard oil sample may change in concentration of each dissolved characteristic gas due to jolting, external pressure and temperature during transportation, reducing the accuracy of online chromatography monitoring device field calibration. Second, the calibration site environment is poor, and laboratory methods cannot be used to configure standard oil samples on site. Finally, the standard oil sample preparation process is complicated, the oil sample shelf life is short, and there is a lack of flexibility in adjusting the target oil sample concentration according to the site conditions.

[0006] The gas content in transformer oil refers to the total content of N2, O2, CO2 and CO in transformer oil. Analysis of gas content is an effective technical means to early detect sealing failure of electrical equipment, avoid internal bubble discharge of ultra-high voltage and extra-high voltage electrical equipment, and prevent water ingress and dampness failure.

[0007] And for the determination of the gas content in transformer oil is mainly through offline sampling detection, the conventional determination method has two kinds of DL / T703-2015 Gas Chromatographic Determination of Gas Content in Insulating Oil and DL / T 423-2009 Determination Method of Gas Content in Insulating Oil Vacuum Pressure Difference Method. The gas chromatography method is the most widely used method for detecting the gas content in transformer oil at present, the detection method mainly utilizes the mechanical oscillation method or the automatic headspace degassing method to remove the gas in the transformer oil, then the gas chromatograph is used to separate and detect each gas component, then the result is calculated, the result is expressed by volume fraction (%), so that the gas content in the transformer oil is obtained. The vacuum pressure difference method for determining the gas content in insulating oil mainly makes the measured oil sample enter the high-vacuum degassing chamber through a proper way, so that the dissolved gas in the test oil is rapidly released, according to the pressure difference value generated by the released gas before and after the test oil enters the degassing chamber, combined with the parameters such as chamber temperature, test oil quantity, degassing chamber volume, degassing chamber temperature, the content of the dissolved gas in the oil is calculated, and the gas content in the measured oil sample is expressed by the volume fraction (%) of the gas to the test oil under the standard condition (101.3kPa, 0℃). The existing gas content detection method needs to take the transformer oil from the transformer station to the laboratory for detection, whether in the oil sample collection, preservation or in the oil sample degassing test process, there is always the disadvantage that the dissolved gas in the oil sample escapes to the outside and the external air enters the oil sample, which affects the test accuracy. SUMMARY

[0008] The technical scheme of the present application is used to solve the problem of how to improve the detection efficiency of the dissolved gas and the gas content in the transformer oil.

[0009] The present application solves the above technical problems by the following technical scheme: The present application provides a detection method based on a dissolved gas and gas content detection device in transformer oil, the detection device comprises valves, peristaltic pumps, flow meters, oil-gas membrane separation modules, mass spectrometry detection modules, low-concentration calibration mixed gas cylinders and high-concentration calibration mixed gas cylinders connected in sequence; the detection method comprises: S1, preheat the device and input double-concentration calibration gas, establish the relationship curve between the concentration of each component gas and the mass spectrometry signal intensity; S2, after heating, the measured oil sample is sent into the oil-gas membrane separation module until the gas-liquid equilibrium state is reached, then the mass spectrometry detection module is started, and the mass spectrometry signal intensity of each component gas is detected; S3, obtaining the mass spectrum characteristic peak, secondary ion peak and interference peak information of each target component gas; for the non-interference component gas, directly using the established relationship curve between the concentration and the mass spectrum signal intensity of each component gas to calculate the concentration of each component gas; for the interference component gas, according to the characteristic peak and the secondary ion peak of each component gas, stripping the peak overlapping mass spectrum signal intensity of each component gas, and then using the response factor to calculate the concentration of each component gas; The method for stripping the peak overlapping mass spectrum signal intensity of each component gas is as follows: At the mass spectrum signal intensity at m / z 28, the N2 characteristic peak, the CO characteristic peak, the C2H4 characteristic peak and the C2H6 secondary ion peak at m / z 28 are stripped; At the mass spectrum signal intensity at m / z 16, the secondary ion peak of O2 at m / z 16 is stripped; At the mass spectrum signal intensity at m / z 26, the secondary ion peak of C2H4 at m / z 26 is stripped; The response factor is determined based on the signal intensity and the concentration ratio of pure single component standard gas at a specific mass-to-charge ratio; S4, converting the gas phase concentration of each component gas into the dissolved gas concentration in the transformer oil by using the Henry's law; S5, calculating the sum of the concentrations of nitrogen, oxygen, carbon monoxide and carbon dioxide to obtain the gas content in the oil.

[0010] Further, the formula of the relationship curve between the concentration and the mass spectrum signal intensity of each component gas in step S1 is as follows: (1) Wherein, is the mass spectrum signal intensity of each component gas, is the calibration curve response coefficient, is the concentration of each component gas.

[0011] Further, the formula of the response factor in step S3 is as follows: (2) Wherein, is the response signal of pure single component standard gas X at m / z Y, is the concentration of pure single component standard gas X.

[0012] Further, the method for stripping the mass spectrum signal intensity of the N2 characteristic peak, the CO characteristic peak, the C2H4 characteristic peak and the C2H6 secondary ion peak at m / z 28 in step S3 is as follows: The secondary ion peak of N2 at m / z 14 is used Perform calibration, through The concentration of the N2 component gas was calculated. Therefore, the mass spectrum signal intensity of the N2 characteristic peak at m / z 28 is: ; The mass spectrometry signal intensity of the secondary ion peak of CO at m / z 12 was used. Perform calibration, through The concentration of CO component gas was calculated. Therefore, the mass spectrum signal intensity of the CO characteristic peak at m / z 28 is: ; The mass spectrometry signal intensity of the minor ion peak of C2H4 at m / z 27 Perform calibration, through The concentration of C2H4 was calculated. Therefore, the mass spectrum signal intensity of the C2H4 characteristic peak at m / z 28 is: ; Mass spectral signal intensity at m / z 30 using the characteristic peak of C2H6 Perform calibration, through The concentration of C2H6 was calculated. Therefore, the mass spectrum signal intensity of the C2H6 minor ion peak at m / z 28 is: .

[0013] Further, the method for separating the secondary ion peak of O2 at m / z 16 in step S3 is as follows: using the characteristic peak of O2 at m / z 32... Perform calibration, through The concentration of O2 was calculated. Its contribution to the mass spectrum signal intensity at m / z 16 is: The methane signal intensity at mass-to-charge ratio 16 is obtained by subtracting the contribution of oxygen from the total signal intensity at mass-to-charge ratio 16, and then the methane concentration is calculated.

[0014] Further, the method for stripping the secondary ion peak of C2H4 at m / z 26 at the mass spectrometry signal intensity in step S3 is as follows: based on the methane concentration... ,pass The mass spectrum signal intensity of the minor ion peak of C2H4 at m / z 26 was calculated. The acetylene signal intensity at mass-to-charge ratio 26 is obtained by subtracting the contribution of ethylene from the total signal intensity at mass-to-charge ratio 26, and then the acetylene concentration is calculated.

[0015] Further, the formula for converting the gas phase concentration of each component gas into the dissolved gas concentration in the transformer oil in step S4 is as follows: (6) (7) wherein H is the Henry coefficient, R is the molar gas constant, T is the temperature of the oil-gas membrane separation module, is the concentration of each component gas, is the Ostwald coefficient.

[0016] Further, one end of the valve is connected to the oil sample inlet, the other end of the valve is connected to the input end of the peristaltic pump, the output end of the peristaltic pump is connected to one end of the flow meter, the other end of the flow meter is connected to the oil inlet of the oil-gas membrane separation module, the gas outlet of the oil-gas membrane separation module is connected to the input end of the mass spectrum detection module, and the oil outlet of the oil-gas membrane separation module is used to discharge the oil sample; the output ends of the low-concentration calibration mixed gas cylinder and the high-concentration calibration mixed gas cylinder are respectively connected to the input end of the mass spectrum detection module through pipelines.

[0017] Further, the detection device further comprises a heating device arranged between the flow meter and the oil-gas membrane separation module, wherein the heating device comprises a conveying pipeline and a constant-temperature water bath heating device; the conveying pipeline is in the shape of a plurality of U-shaped pipelines connected in series, and is arranged in the constant-temperature water bath heating device; the input end of the conveying pipeline is arranged below the constant-temperature water bath heating device, and the output end of the conveying pipeline is arranged above the constant-temperature water bath heating device; the input end of the conveying pipeline is connected to the output end of the flow meter, and the output end of the conveying pipeline is connected to the oil inlet of the oil-gas membrane separation module.

[0018] Further, the oil-gas membrane separation module is arranged in a constant-temperature box.

[0019] Further, the separation membrane used by the oil-gas membrane separation module is an oil-resistant polydimethylsiloxane flat plate type separation membrane or an AF2400 material separation membrane.

[0020] Further, the mass spectrum detection module adopts a small four-pole mass spectrometer.

[0021] The application further provides an electronic device comprising a memory and a processor, wherein the memory is used to store a program supporting the processor to execute the above detection method, and the processor is configured to execute the program stored in the memory.

[0022] The application further provides a storage medium, wherein the storage medium stores a computer program, and the computer program is used to execute the steps of the above detection method when executed by a processor.

[0023] The application has the following beneficial effects: The gas balance-membrane sample introduction mass spectrometry detection technology is used for realizing rapid detection of dissolved gas in transformer oil without additional configuration of standard oil sample for calibration, greatly shortening the calibration period and single calibration operation time, and breaking through the limitation of existing offline detection (such as gas chromatography, vacuum pressure difference method) needing on-site sampling; through the combination of oil-gas separation membrane and mass spectrometry detection, the concentrations of nitrogen, oxygen, carbon monoxide and carbon dioxide in the transformer oil can be simultaneously determined online, solving the problem that the traditional method can only measure the total gas content or a single component, and providing more comprehensive gas component data for equipment sealing performance evaluation; two kinds of mixed standard gases with different concentrations are used for alternating calibration, eliminating interference, without frequent use of standard oil calibration, solving the problem that the existing method (such as density method) needs frequent calibration due to environmental fluctuations; the mass spectrometer is used to analyze the content of the target gas in the gas phase combined with peak interference calibration, and then the concentrations of each dissolved gas in the oil sample are calculated by reverse calculation according to the Henry's law at the system temperature, which not only obtains the total gas content in the oil to evaluate the sealing state of the equipment through concentration accumulation, but also realizes real-time diagnosis of equipment failure based on the concentration change of characteristic gas, greatly improving the detection efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a structural diagram of a dissolved gas and gas content detection device for transformer oil according to an embodiment of the present application; Figure 2 is a structural diagram of a heating device of a dissolved gas and gas content detection device for transformer oil according to an embodiment of the present application; Figure 3 is a flow chart of a detection method of a dissolved gas and gas content detection device for transformer oil based on the embodiment one according to an embodiment of the present application; Figure 4 is a relationship curve diagram between the concentration of H2 component gas and the mass spectrometry signal intensity. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme of the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0026] The technical scheme of the present application will be further described below in combination with the drawings in the specification and specific embodiments: Embodiment One As Figure 1As shown, the embodiment provides a device for detecting dissolved gas and gas content in transformer oil, comprising: a valve 10, a peristaltic pump 11, a flow meter 12, an oil-gas membrane separation module 13, a mass spectrometry detection module 14, a low-concentration calibration mixed gas cylinder 15, and a high-concentration calibration mixed gas cylinder 16; the mass spectrometry detection module 14 comprises: a first pressure-reducing valve 141, a second pressure-reducing valve 142, a mass spectrometer 143, a turbo pump 144, and a diaphragm pump 145; one end of the valve 10 is an oil sample inlet, the other end of the valve 10 is sealingly connected to the input end of the peristaltic pump 11, the output end of the peristaltic pump 11 is sealingly connected to one end of the flow meter 12, the other end of the flow meter 12 is sealingly connected to the oil inlet of the oil-gas membrane separation module 13, the gas outlet of the oil-gas membrane separation module 13 is sealingly connected to the input end of the mass spectrometry detection module 14, and the oil outlet of the oil-gas membrane separation module 13 is used for discharging the oil sample; the output ends of the low-concentration calibration mixed gas cylinder 15 and the high-concentration calibration mixed gas cylinder 16 are respectively sealingly connected to the input end of the mass spectrometry detection module 14 through pipelines.

[0027] Preferably, a heating device is further arranged between the flow meter 12 and the oil-gas membrane separation module 13. Figure 2 As shown, the heating device comprises: a conveying pipeline 20 and a constant-temperature water bath heating device 21; the conveying pipeline 20 is in the shape of multiple U-shaped pipelines connected in series, which is conducive to increasing the heating area; the conveying pipeline 20 is arranged in the constant-temperature water bath heating device 21, which is filled with constant-temperature hot water and used for heating the transformer oil in the conveying pipeline 20; the input end of the conveying pipeline 20 is arranged below the constant-temperature water bath heating device 21, and the output end of the conveying pipeline 20 is arranged above the constant-temperature water bath heating device 21; the input end of the conveying pipeline 20 is sealingly connected to the output end of the flow meter 12, and used for inputting the oil sample; and the output end of the conveying pipeline 20 is sealingly connected to the oil inlet of the oil-gas membrane separation module 13. The oil-gas membrane separation module 13 is arranged in a constant-temperature box, the temperature of which is set to 50℃, and a temperature sensor is arranged to ensure that the Henry coefficient is constant during the gas diffusion process.

[0028] Preferably, the separation membrane used in the oil-gas membrane separation module 13 is an oil-resistant polydimethylsiloxane (PDMS) flat separation membrane. In addition, for high-viscosity oil samples (such as No. 45 transformer oil, the kinematic viscosity of which at 25℃ is 1.5 times or more than that of No. 25 transformer oil), the separation membrane can be replaced with a separation membrane made of AF2400 or the like to improve the applicability of the device.

[0029] Preferably, the mass spectrometry detection module 14 adopts a small quadrupole mass spectrometer (mass range 1-100 u), sets up a characteristic gas detection channel (such as C2H2: 26 m / z, CH4: 16 m / z, etc.), and can also identify possible interference signal peaks. Equipped with an electron multiplier (detection limit ≤0.1 μL / L) for accurate detection of low-concentration fault gases (such as C2H2, the concentration is usually lower than 5 μL / L when the transformer is locally discharged); a Faraday cup detector is also configured synchronously, which is mainly suitable for detecting high-concentration gas components such as nitrogen (the nitrogen content in oil is usually 1000-5000 μL / L), meeting different detection accuracy requirements, and the two detectors can be automatically switched according to the detection target without manual intervention.

[0030] A low-concentration calibration mixed gas cylinder 15 and a high-concentration calibration mixed gas cylinder 16 are provided to realize oil-free calibration, and double-concentration multi-component mixed gas is used as a calibration standard to avoid the storage and pollution problems of oil samples.

[0031] The target component gas concentrations of the low-concentration calibration mixed gas in the low-concentration calibration mixed gas cylinder 15 are the gas concentrations in the normal operating state of the transformer, specifically: H2=5 μL / L, CH4=10 μL / L, C2H2=1 μL / L, C2H4=5 μL / L, C2H6=5 μL / L, CO=10 μL / L, CO2=50 μL / L, and the volume fractions of N2 and O2 are 79% and 21% respectively (simulating the air component ratio).

[0032] The target component gas concentrations of the high-concentration calibration mixed gas in the high-concentration calibration mixed gas cylinder 16 are 50 times those of the low-concentration calibration mixed gas, specifically: H2=250 μL / L, CH4=500 μL / L, C2H2=50 μL / L, C2H4=250 μL / L, C2H6=250 μL / L, CO=500 μL / L, CO2=2500 μL / L, and the ratio of N2 to O2 remains unchanged, covering the concentration range when the transformer is in fault (such as electric arc discharge, overheating) and the seal is ineffective.

[0033] Embodiment Two As shown in Figure 3 The embodiment provides a detection method of the transformer oil dissolved gas and gas content detection device based on the embodiment one, which comprises the following steps: Step 1, device preheating preparation 1) Turn on the thermostat, set the temperature to 50°C (the Ostwald coefficient of the oil at this temperature is known, and after the temperature is stabilized (fluctuation ≤0.5°C, about 15 min); 2) Connect low concentration calibration mixed gas cylinder 15 and high concentration calibration mixed gas cylinder 16 respectively, check pipeline sealing (pressure test: 1 atm pressure for 5 min, pressure drop ≤0.01 atm); 3) Start the mass spectrometry detection module 14, preheat for 30 min, set the detection parameters: ion source temperature 200℃, electron energy 70 eV, scanning rate 1000 u / s, detection channel select nine target component gases in Table 1.

[0034] Step 2, use double concentration calibration mixed gas to establish the relationship curve between the concentration of each component gas and the mass spectrometry signal intensity 1) Open the electromagnetic valve in front of the low concentration calibration mixed gas cylinder 15, adjust the sample flow rate of the gas entering the mass spectrometry detection module 14 to 5 mL / min, and record the mass spectrometry signal intensity of each component gas after the mass spectrometry signal of the mass spectrometry detection module 14 is stable (detection signal fluctuation ≤2%, about 2 min), which is: , , , , , , , , .

[0035] 2) Open the electromagnetic valve in front of the high concentration calibration mixed gas cylinder 16, adjust the sample flow rate of the gas entering the mass spectrometry detection module 14 to 5 mL / min, and record the mass spectrometry signal intensity of each component gas after the mass spectrometry signal of the mass spectrometry detection module 14 is stable (detection signal fluctuation ≤2%, about 2 min), which is: , , , , , , , , .

[0036] 3) Since the concentration of calibration mixed gas in the low concentration calibration mixed gas cylinder 15 and the high concentration calibration mixed gas cylinder 16 is known, the relationship curve between the concentration of each component gas and the mass spectrometry signal intensity can be established. Taking H2 component gas as an example, the concentration of H2 component gas in the low concentration calibration mixed gas is , the concentration of H2 component gas in the high concentration calibration mixed gas is , and the relationship curve between the concentration of H2 component gas and the mass spectrometry signal intensity is shown in Figure 4 .

[0037] The method for establishing the relationship curve between the concentration of the remaining component gas and the mass spectrum signal intensity is the same as that of the H2 component gas, which will not be described here.

[0038] The relationship curve between the concentration of each component gas and the mass spectrum signal intensity is summarized as: (1) wherein, is the mass spectrum signal intensity of each component gas, is the calibration curve response coefficient, is the concentration of each component gas.

[0039] Step 3, oil-gas membrane separation and mass spectrum detection Open valve 10 and start peristaltic pump 11 to send the oil sample to be tested into oil-gas membrane separation module 13 for oil-gas separation after heating until reaching a gas-liquid equilibrium state, and then open mass spectrum detection module 14 to detect the mass spectrum signal intensity of each component gas.

[0040] Step 4, concentration calculation of each component gas To solve the peak overlap interference problem in mass spectrum detection, the characteristic peak, secondary ion peak and interference peak of each target component gas need to be determined, and the specific parameters are shown in Table 1.

[0041] Table 1. Characteristic peak, secondary ion peak and interference peak parameters of target component gas

[0042] As can be seen from Table 1, the non-interference components are: H2 (at m / z 2), C2H6 (at m / z 30), CO2 (at m / z 44), and O2 (at m / z 32). There are overlapping peaks between N2, CO, C2H4 and C2H6 at m / z 28, and there is interference between them. There are overlapping peaks between CH4 and O2 at m / z 16, and there is interference between them. There are overlapping peaks between C2H2 and C2H4 at m / z 26, and there is interference between them.

[0043] 4.1, concentration calculation of non-interference component gas For non-interference component gases H2: m / z 2, C2H6: m / z 30, CO2: m / z 44, and O2: m / z 32, the mass spectrum signal intensity of each component gas detected by mass spectrum detection module 14 , combined with formula (1), the concentration of each component gas can be calculated as .

[0044] 4.2, concentration calculation of interference component gas (1) Definition and calculation of response factor The response factor is defined as follows: (2) wherein, is the response signal of pure single component standard gas X (X is N2, O2, CO, CH4, C2H2, C2H4, C2H6) at m / z Y, is the concentration of pure single component standard gas X, such as concentration is the secondary ion peak N of pure nitrogen gas with concentration of 100 μL / L + is the response signal at m / z 14 (Y = 14) is 1000, then the response factor , and so on for the response factors of other component peaks, the response factor is a fixed parameter for the same equipment.

[0045] The response factor of each component gas at each m / z peak is calculated The single component pure gas with concentration of 500 μL / L of H2, CH4, C2H6, C2H4, C2H2, CO, CO2, concentration of 2000 μL / L of N2, concentration of 2000 μL / L of O2 is respectively introduced, the characteristic peak and secondary ion peak signal of different m / z are collected, and then the response factor of each component gas at each m / z peak is calculated according to formula (2).

[0046] (2) Concentration calculation of C2H6 component gas The mass spectrum signal intensity of the characteristic peak of C2H6 at m / z 30 is used for calibration, and the concentration of C2H6 is calculated by Therefore, the mass spectrum signal intensity of the secondary ion peak of C2H6 at m / z 28 is: .

[0047] (3) Concentration calculation of N2, CO, C2H4 component gases with peak overlap at m / z 28 The characteristic peaks of N2, CO, C2H4, and the secondary ion peak of C2H6 exist overlap at the mass spectrum signal intensity at m / z 28, and therefore in order to accurately calculate the concentration of each component gas, the mass spectrum signal intensity of the characteristic peaks of N2, CO, C2H4, and the secondary ion peak of C2H6 at m / z 28 needs to be stripped.

[0048] 1) Concentration calculation of N2 component gas ​The mass spectrum signal intensity at m / z 28 overlaps with the CO characteristic peak, C2H4 characteristic peak, and C2H6 secondary ion peak, so in order to accurately calculate the concentration of the N2 component gas, the mass spectrum signal intensity of the CO characteristic peak, C2H4 characteristic peak, and C2H6 secondary ion peak at m / z 28 needs to be stripped, and the specific method is as follows: The mass spectrum signal intensity at m / z 14 of the secondary ion peak of N2 is used Calibration is performed by The concentration of the N2 component gas is calculated Therefore, the mass spectrum signal intensity of the N2 characteristic peak at m / z 28 is: .

[0049] 2) Concentration calculation of the CO component gas The mass spectrum signal intensity at m / z 12 of the secondary ion peak of CO is used Calibration is performed by The concentration of the CO component gas is calculated Therefore, the mass spectrum signal intensity of the CO characteristic peak at m / z 28 is: .

[0050] 3) Concentration calculation of the C2H4 component gas The mass spectrum signal intensity at m / z 27 of the secondary ion peak of C2H4 is used Calibration is performed by The concentration of C2H4 is calculated Therefore, the mass spectrum signal intensity of the C2H4 characteristic peak at m / z 28 is: .

[0051] 5) Reverse verification The mass spectrum signal intensity of the N2 characteristic peak at m / z 28 obtained in the above calculation process , the mass spectrum signal intensity of the CO characteristic peak at m / z 28 , the mass spectrum signal intensity of the C2H4 characteristic peak at m / z 28 , and the mass spectrum signal intensity of the C2H6 secondary ion peak at m / z 28 The sum of the four is equal to the total signal intensity at m / z 28 That is: (3) (4) Concentration calculation of the CH4 component gas with overlapping peaks at m / z 16 The mass spectrum signal intensity of CH4 component gas at m / z 16 overlaps with the secondary ion peak of O2, so in order to accurately calculate the concentration of CH4 component gas, the mass spectrum signal intensity of the secondary ion peak of O2 at m / z 16 needs to be stripped, and the specific method is as follows: The mass spectrum signal intensity of the characteristic peak of O2 at m / z 32 is used as the reference value Calibration is performed by The concentration of O2 is calculated , and the mass spectrum signal intensity at m / z 16 is contributed by: ; therefore, the mass spectrum signal intensity of CH4 component gas at m / z 16 is obtained by the difference between the total mass spectrum signal intensity and : (4) The concentration of CH4 is calculated by : .

[0052] (5) Concentration calculation of C2H2 component gas with overlapping peak at m / z 26 The mass spectrum signal intensity of C2H2 component gas at m / z 26 overlaps with the secondary ion peak of C2H4, so in order to accurately calculate the concentration of C2H2 component gas, the mass spectrum signal intensity of the secondary ion peak of C2H4 at m / z 26 needs to be stripped, and the specific method is as follows: According to the concentration of C2H4 obtained in step (3) item 3) , the mass spectrum signal intensity of the secondary ion peak of C2H4 at m / z 26 is calculated by : Therefore, the mass spectrum signal intensity of C2H2 component gas at m / z 26 is obtained by the difference between the total mass spectrum signal intensity and : (5) The concentration of C2H4 is calculated by : .

[0053] Step 5, concentration conversion According to Henry's law, the concentrations of each component gas calculated in step 4 are converted into gas concentrations in the oil sample , and the conversion formula is as follows: (6) (7) where H is the Henry coefficient, R is the molar gas constant, T is the temperature of the oil-gas membrane separation module, is Ostwald coefficient. Table 2 below is the value of Ostwald coefficient of each component gas in transformer oil at 50℃.

[0054] Table 2 Value of Ostwald coefficient of each component gas in transformer oil at 50℃

[0055] Step 6, gas content calculation The gas content in transformer oil is the sum of the concentrations of nitrogen, oxygen, carbon monoxide and carbon dioxide in the oil, so after converting the concentration of each component gas to the gas concentration in the oil sample in step 5, the value of the gas content in the transformer oil can be obtained by adding.

[0056] Example three An electronic device, comprising a memory for storing a program supporting the processor to execute the detection method of the dissolved gas and gas content detection device in transformer oil in example two, and a processor configured to execute the program stored in the memory.

[0057] Example four A storage medium, a computer program is stored on the storage medium, the computer program is executed by the processor to perform the steps of the detection method of the dissolved gas and gas content detection device in transformer oil in example two.

[0058] The above examples are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A detection method based on a device for detecting dissolved gases and gas content in transformer oil, the detection device comprising, in sequence, a valve, a peristaltic pump, a flow meter, an oil-gas film separation module, a mass spectrometry detection module, a low-concentration calibration mixed gas cylinder, and a high-concentration calibration mixed gas cylinder; characterized in that, The detection method includes: S1. Preheat the device and introduce dual-concentration calibration gas to establish the relationship curve between the concentration of each component gas and the mass spectrometry signal intensity. S2. The oil sample to be tested is heated and then sent into the oil-gas film separation module until the gas-liquid equilibrium is reached. Then the mass spectrometry detection module is turned on to detect the mass spectrometry signal intensity of each component gas. S3. Obtain information on the mass spectrometry characteristic peaks, minor ion peaks, and interference peaks of each target component gas. For gas without interference, directly use the established relationship curve between the concentration of each component gas and the mass spectrometry signal intensity to calculate the concentration of each component gas. For gas with interference, based on the characteristic peaks and minor ion peaks of each component gas, separate the overlapping mass spectrometry signal intensities of each component gas peak, and then use the response factor to calculate the concentration of each component gas. The method for separating the mass spectrometry signal intensities of the overlapping peaks of each component gas is as follows: At the mass spectrum signal intensity at m / z 28, the characteristic peaks of N2, CO, C2H4, and C2H6 minor ion peaks were stripped from the mass spectrum signal intensity at m / z 28. At the mass spectrum signal intensity at m / z 16, the minor ion peak of O2 is stripped from the mass spectrum signal intensity at m / z 16; At the mass spectrum signal intensity of m / z 26, the minor ion peak of C2H4 is stripped from the mass spectrum signal intensity at m / z 26; The response factor is determined based on the ratio of signal intensity to concentration of a pure single-component standard gas at a specific mass-to-charge ratio; S4. Use Henry's Law to convert the gas phase concentration of each component gas into the dissolved gas concentration in the transformer oil. S5. Calculate the sum of the concentrations of nitrogen, oxygen, carbon monoxide, and carbon dioxide to obtain the gas content in the oil.

2. The detection method according to claim 1, characterized in that, The formula for the relationship curve between the concentration of each component gas and the mass spectrometry signal intensity in step S1 is as follows: （1） in, The mass spectrometry signal intensity of each component gas, To calibrate the response coefficients of the curve, The concentration of each component gas.

3. The detection method according to claim 1, characterized in that, The formula for the response factor mentioned in step S3 is as follows: （2） in, The response signal of pure, single-component standard gas X at m / z Y. The concentration of a pure, single-component standard gas X.

4. The detection method according to claim 3, characterized in that, The method for separating the mass spectrometry signal intensity of the N2 characteristic peak, CO characteristic peak, C2H4 characteristic peak, and C2H6 minor ion peak at m / z 28 in step S3 is as follows: The mass spectrometry signal intensity of the secondary ion peak of N2 at m / z 14 Perform calibration, through The concentration of the N2 component gas was calculated. Therefore, the mass spectrum signal intensity of the N2 characteristic peak at m / z 28 is: ; The mass spectrometry signal intensity of the secondary ion peak of CO at m / z 12 was used. Perform calibration, through The concentration of CO component gas was calculated. Therefore, the mass spectrum signal intensity of the CO characteristic peak at m / z 28 is: ; The mass spectrometry signal intensity of the minor ion peak of C2H4 at m / z 27 Perform calibration, through The concentration of C2H4 was calculated. Therefore, the mass spectrum signal intensity of the C2H4 characteristic peak at m / z 28 is: ; Mass spectral signal intensity at m / z 30 using the characteristic peak of C2H6 Perform calibration, through The concentration of C2H6 was calculated. Therefore, the mass spectrum signal intensity of the C2H6 minor ion peak at m / z 28 is: .

5. The detection method according to claim 4, characterized in that, The method for separating the secondary ion peak of O2 at m / z 16, as described in step S3, is as follows: The characteristic peak of O2 at m / z 32 is used as the mass spectrometry signal intensity. Perform calibration, through The concentration of O2 was calculated. Its contribution to the mass spectrum signal intensity at m / z 16 is: The methane signal intensity at mass-to-charge ratio 16 is obtained by subtracting the contribution of oxygen from the total signal intensity at mass-to-charge ratio 16, and then the methane concentration is calculated.

6. The detection method according to claim 5, characterized in that, The method for separating the minor ion peak of C2H4 at m / z 26, as described in step S3, is as follows: based on the methane concentration... ,pass The mass spectrum signal intensity of the minor ion peak of C2H4 at m / z 26 was calculated. The acetylene signal intensity at mass-to-charge ratio 26 is obtained by subtracting the contribution of ethylene from the total signal intensity at mass-to-charge ratio 26, and then the acetylene concentration is calculated.

7. The detection method according to claim 1, characterized in that, The formula for converting the gas phase concentration of each component gas into the dissolved gas concentration in transformer oil in step S4 is as follows: （6） （7） Where H is the Henry's law constant, R is the molar gas constant, and T is the temperature of the oil-gas film separation module. The concentrations of each component gas, This is the Ostwald coefficient.

8. The detection method according to claim 1, characterized in that, One end of the valve is the oil sample inlet, and the other end of the valve is sealed to the input end of the peristaltic pump. The output end of the peristaltic pump is sealed to one end of the flow meter, and the other end of the flow meter is sealed to the oil inlet of the oil-gas film separation module. The gas outlet of the oil-gas film separation module is sealed to the input end of the mass spectrometry detection module, and the oil outlet of the oil-gas film separation module is used to discharge the oil sample. The output ends of the low-concentration calibration mixed gas cylinder and the high-concentration calibration mixed gas cylinder are respectively sealed to the input end of the mass spectrometry detection module through pipelines.

9. The detection method according to claim 8, characterized in that, It also includes a heating device disposed between the flow meter and the oil-gas film separation module. The heating device includes a conveying pipe and a constant temperature water bath heating device. The conveying pipe is in the form of multiple U-shaped pipes connected in series and is disposed in the constant temperature water bath heating device. The inlet of the conveying pipe is disposed below the constant temperature water bath heating device, and the outlet of the conveying pipe is disposed above the constant temperature water bath heating device. The inlet of the conveying pipe is sealed to the output end of the flow meter, and the outlet of the conveying pipe is sealed to the oil inlet of the oil-gas film separation module.

10. The detection method according to claim 8, characterized in that, The oil-gas film separation module is installed in a constant temperature chamber.

11. The detection method according to claim 8, characterized in that, The oil-gas membrane separation module uses a flat sheet membrane made of oil-resistant polydimethylsiloxane or a membrane made of AF2400 material.

12. The detection method according to claim 8, characterized in that, The mass spectrometry detection module uses a small quadrupole mass spectrometer.

13. An electronic device, comprising a memory and a processor, characterized in that, The memory is used to store a program that supports the processor in executing the detection method according to any one of claims 1 to 12, and the processor is configured to execute the program stored in the memory.

14. A storage medium storing a computer program, characterized in that, The computer program is executed by the processor to perform the steps of the detection method according to any one of claims 1 to 12.

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