A device and method for detecting dissolved gases and gas content in transformer oil

Abstract

The application discloses a device and method for detecting dissolved gas and gas content in transformer oil, and belongs to the technical field of power equipment state monitoring. The device comprises a valve, a peristaltic pump, a flow meter, an oil-gas membrane separation module, a mass spectrometric detection module, a low-concentration calibration mixed gas cylinder and a high-concentration calibration mixed gas cylinder. The method utilizes a mass spectrometer and combines peak interference to calibrate and analyze the content of target gas in gas phase, and then inversely calculates the concentration of each dissolved gas in the oil sample through Henry's law, so that the detection efficiency is greatly improved, the rapid, online and accurate monitoring of multiple dissolved gases and gas content in transformer oil is realized, and the device is suitable for transformer fault diagnosis and sealed state evaluation.

Description

Technical Field

[0001] This invention belongs to the field of power equipment condition monitoring technology, and relates to a device and method for detecting dissolved gases and gas content in transformer oil. Background Technology

[0002] Oil-immersed transformers are core equipment in power systems, utilizing transformer oil as an insulation and cooling medium to ensure safe operation. During operation, transformer oil deteriorates due to insulation faults (such as aging and discharge), 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 gases in transformer oil enables effective online monitoring of the internal operating status of oil-immersed transformers by analyzing the dissolved gases in the insulating oil. This allows for timely detection and diagnosis of internal faults, thereby ensuring the safe and stable operation of the transformer. The national standard "Guidelines for Transformer Oil Maintenance and Management" (GB / T 14542-2017) specifies requirements for the gas content of transformers and reactors at different voltage levels after hot oil circulation and during operation.

[0004] Currently, the main workflow of online dissolved gas monitoring devices in oil based on chromatography or photoacoustic spectroscopy is to first separate the gases dissolved in the oil, and then monitor and analyze the separated gases. Due to the inherent limitations of the gas separation and detection technologies, the single monitoring cycle is longer than 1 hour, making it increasingly difficult for existing online monitoring devices to meet the demands of rapid monitoring, especially for large oil-filled equipment serving ultra-high voltage power transmission and transformation systems where faults develop rapidly. For example, chromatography requires a complex separation process, and the single detection cycle typically exceeds 1 hour. Photoacoustic spectroscopy, due to its low gas separation efficiency, also has a detection cycle of over 40 minutes, making rapid response impossible. Furthermore, field operation shows that during long-term operation, online dissolved gas monitoring devices frequently experience missed or false alarms due to equipment aging, leading to delayed transformer maintenance and potential transformer damage, or unnecessary shutdowns for maintenance. Therefore, it is necessary to conduct on-site verification and analysis of the accuracy of online dissolved gas detection devices. The main process involves preparing working oil samples with different concentrations, connecting the online monitoring device to be calibrated to the inlet and outlet of the working oil sample tank, testing the working oil sample, and simultaneously manually sampling and testing with a laboratory insulating oil chromatograph. The chromatograph results are used as reference values, and the online monitoring device's results are compared with the reference values ​​to evaluate the device's detection error. Since the detection cycle of the online monitoring device is generally 2 hours, and sometimes even 4 hours, repeatability tests require six repetitions, and calibration with three standard oil samples (low, medium, and high concentrations) is typically required, the entire calibration process is time-consuming, and manual sampling and testing are inefficient. Furthermore, the laboratory-prepared standard oil samples are greatly affected by temperature, pressure, and transportation disturbances, and their gas concentrations are prone to change, leading to decreased calibration accuracy.

[0005] Patent application CN119104667A discloses an online transformer oil chromatography detection device and method. This method involves pre-configuring standard oil samples of different concentrations and storing them in specific storage containers. The system then controls corresponding valves to automatically switch between sampling the transformer standard oil samples, enabling data comparison and verification between the online and offline monitoring devices. However, it still requires configuring standard oil samples and performing on-site verification of the online device. Patent application CN111239304A discloses a reference oil sample preparation system for the gaseous component content of insulating oil. This system can configure reference oil samples of high, medium, and low concentrations, and can meet the target reference oil sample concentration requirements for multiple instruments. However, it suffers from drawbacks such as large device size, difficulty in portability, and the inability to recycle calibration oil samples. Existing field calibration devices and methods for online monitoring of dissolved gases in transformer oil based on standard oil samples have the following shortcomings: First, the concentrations of various characteristic dissolved gases in the oil change during transportation due to bumps, external pressure, and temperature, reducing the accuracy of on-site calibration of the online chromatographic monitoring device. Second, the harsh environmental conditions at the calibration site make it impossible to prepare standard oil samples on-site using laboratory methods. Finally, the standard oil sample preparation process is cumbersome, the oil sample storage time is short, and there is a lack of flexibility in adjusting the concentration of the target oil sample according to the on-site conditions.

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

[0007] The determination of gas content in transformer oil is mainly carried out through offline sampling. Common methods include "Gas Chromatography Determination of Gas Content in Insulating Oil" (DL / T703—2015) and "Vacuum Pressure Difference Method for Determination of Gas Content in Insulating Oil" (DL / T 423—2009). Gas chromatography is currently the most widely used method for detecting gas content in transformer oil. The method primarily utilizes mechanical oscillation or automatic headspace degassing to remove gases from the transformer oil. Then, a gas chromatograph separates and detects each gas component, and the results are calculated and expressed as a volume fraction (%) to determine the gas content in the transformer oil. The vacuum differential pressure method for determining the gas content in insulating oil mainly involves introducing the oil sample into a high-vacuum degassing chamber through an appropriate method, causing the dissolved gases in the oil to be rapidly released. The dissolved gas content in the oil is calculated based on the pressure difference generated before and after the oil enters the degassing chamber, combined with parameters such as room temperature, oil volume, degassing chamber volume, and degassing chamber temperature. The gas content in the oil sample is expressed as the volume fraction (%) of the gas in the oil sample under standard conditions (101.3 kPa, 0℃). Existing gas content detection methods require the transformer oil to be taken from the substation site and brought back to the laboratory for testing. Whether during oil sample collection, preservation, or degassing testing, there are always drawbacks such as the escape of dissolved gases from the oil sample and the entry of external air into the oil sample, affecting the accuracy of the test. Summary of the Invention

[0008] The technical solution of this invention is used to solve the problem of how to improve the detection efficiency of dissolved gases and gas content in transformer oil.

[0009] The present invention solves the above-mentioned technical problems through the following technical solutions:

[0010] This invention provides a detection method based on a device for detecting dissolved gases and gas content in transformer oil. The detection device includes, 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. The detection method includes:

[0011] 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.

[0012] 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.

[0013] 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.

[0014] The method for separating the mass spectrometry signal intensities of the overlapping peaks of each component gas is as follows:

[0015] 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.

[0016] 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;

[0017] 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;

[0018] 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;

[0019] S4. Use Henry's Law to convert the gas phase concentration of each component gas into the dissolved gas concentration in the transformer oil.

[0020] S5. Calculate the sum of the concentrations of nitrogen, oxygen, carbon monoxide, and carbon dioxide to obtain the gas content in the oil.

[0021] Furthermore, 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:

[0022] (1)

[0023] in, The mass spectrometry signal intensity of each component gas, To calibrate the response coefficients of the curve, The concentration of each component gas.

[0024] Furthermore, the formula for the response factor mentioned in step S3 is as follows:

[0025] (2)

[0026] in, The response signal of pure, single-component standard gas X at m / z Y is given. The concentration of a pure, single-component standard gas X.

[0027] Furthermore, 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:

[0028] 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: ;

[0029] 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: ;

[0030] 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: ;

[0031] 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: .

[0032] 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.

[0033] 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.

[0034] Furthermore, 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:

[0035] (6)

[0036] (7)

[0037] 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.

[0038] Furthermore, one end of the valve is an oil sample inlet, 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, 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, the oil outlet of the oil-gas film separation module is used to discharge the oil sample, and 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.

[0039] Furthermore, the detection device also includes a heating device disposed between the flow meter and the oil-gas film separation module. The heating device includes a delivery pipe and a constant temperature water bath heating device. The delivery 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 delivery pipe is disposed below the constant temperature water bath heating device, and the outlet of the delivery pipe is disposed above the constant temperature water bath heating device. The inlet of the delivery pipe is sealed to the output end of the flow meter, and the outlet of the delivery pipe is sealed to the oil inlet of the oil-gas film separation module.

[0040] Furthermore, the oil-gas film separation module is installed in a constant temperature chamber.

[0041] Furthermore, the oil-gas membrane separation module uses a flat sheet membrane made of oil-resistant polydimethylsiloxane or a membrane made of AF2400 material.

[0042] Furthermore, the mass spectrometry detection module employs a small quadrupole mass spectrometer.

[0043] The present invention also provides an electronic device, including a memory and a processor, wherein the memory is used to store a program that supports the processor in executing the above-described detection method, and the processor is configured to execute the program stored in the memory.

[0044] The present invention also provides a storage medium storing a computer program, which, when run by a processor, executes the steps of the above-described detection method.

[0045] The beneficial effects of this invention are as follows:

[0046] This invention utilizes the gas balance characteristics of gas balance-membrane mass spectrometry detection technology to achieve rapid detection of dissolved gases in transformer oil without the need for additional standard oil samples for calibration. This significantly shortens the calibration cycle and the duration of a single calibration operation, overcoming the limitations of existing offline detection methods (such as gas chromatography and vacuum differential pressure methods) that require on-site sampling. By combining oil-gas separation membranes with mass spectrometry detection, the concentrations of nitrogen, oxygen, carbon monoxide, and carbon dioxide in transformer oil can be simultaneously measured online, solving the problem that traditional methods can only measure total gas content or single components, providing more comprehensive gas composition data for equipment sealing performance evaluation. Alternating calibration with mixed standard gases of two concentrations eliminates interference and eliminates the need for frequent standard oil calibration, solving the problem of frequent calibration due to environmental fluctuations in existing methods (such as density methods). The mass spectrometer, combined with peak interference calibration, analyzes the content of target gases in the gas phase, and then uses Henry's law at system temperature to back-calculate the concentration of each dissolved gas in the oil sample. This allows for both the assessment of equipment sealing status by accumulating concentrations and real-time diagnosis of equipment faults based on changes in characteristic gas concentrations, greatly improving detection efficiency. Attached Figure Description

[0047] Figure 1 This is a structural diagram of the device for detecting dissolved gas and gas content in transformer oil according to Embodiment 1 of the present invention;

[0048] Figure 2 This is a structural diagram of the heating device of the transformer oil dissolved gas and gas content detection device according to Embodiment 1 of the present invention;

[0049] Figure 3 This is a flowchart of the detection method of the dissolved gas and gas content detection device in transformer oil based on the first embodiment of the present invention in Embodiment 2;

[0050] Figure 4 This is a graph showing the relationship between the concentration of H2 component gas and the intensity of the mass spectrometry signal. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0053] Example 1

[0054] like Figure 1 As shown, this embodiment provides a device for detecting dissolved gases and gas content in transformer oil, including: a valve 10, a peristaltic pump 11, a flow meter 12, an oil-gas film 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 includes: a first pressure reducing valve 141, a second pressure reducing valve 142, a mass spectrometer 143, a turbine pump 144, and a diaphragm pump 145; one end of the valve 10 is the oil sample inlet, and the other end of the valve 10 is connected to... The input end of the peristaltic pump 11 is sealed and connected, the output end of the peristaltic pump 11 is sealed and connected to one end of the flow meter 12, the other end of the flow meter 12 is sealed and connected to the oil inlet of the oil-gas film separation module 13, the gas outlet of the oil-gas film separation module 13 is sealed and connected to the input end of the mass spectrometry detection module 14, and the oil outlet of the oil-gas film separation module 13 is used to discharge 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 sealed and connected to the input end of the mass spectrometry detection module 14 through pipelines.

[0055] Preferably, a heating device is also provided between the flow meter 12 and the oil-gas film separation module 13. For example... Figure 2As shown, the heating device includes: a conveying pipe 20 and a constant-temperature water bath heating device 21; the conveying pipe 20 is in the form of multiple U-shaped pipes connected in series, which helps to increase the heating area; the conveying pipe 20 is installed in the constant-temperature water bath heating device 21, which is filled with constant-temperature hot water for heating the transformer oil in the conveying pipe 20; the inlet of the conveying pipe 20 is located below the constant-temperature water bath heating device 21, and the outlet of the conveying pipe 20 is located above the constant-temperature water bath heating device 21; the inlet of the conveying pipe 20 is sealed to the output end of the flow meter 12 for inputting oil samples, and the outlet of the conveying pipe 20 is sealed to the inlet of the oil-gas film separation module 13. The oil-gas film separation module 13 is installed in a constant-temperature chamber, the temperature is set to 50℃, and a temperature sensor is configured to ensure that the Henry's coefficient remains constant during gas diffusion.

[0056] Preferably, the oil-gas membrane separation module 13 uses a flat sheet membrane made of oil-resistant polydimethylsiloxane (PDMS). Furthermore, for high-viscosity oil samples (such as No. 45 transformer oil, whose kinematic viscosity at 25°C is more than 1.5 times that of No. 25 transformer oil), the membrane can be replaced with a membrane made of materials such as AF2400 to improve the applicability of the device.

[0057] Preferably, the mass spectrometry detection module 14 employs a small quadrupole mass spectrometer (mass range 1-100 u), equipped with a characteristic gas detection channel (such as C2H2: 26 m / z, CH4: 16 m / z, etc.), and can simultaneously identify potential interference signal peaks. It is equipped with an electron multiplier (detection limit ≤0.1 μL / L) for accurate detection of low-concentration fault gases (such as C2H2, whose concentration is often below 5 μL / L during transformer partial discharge faults); a Faraday cup detector is simultaneously configured, primarily suitable for detecting high-concentration gas components such as nitrogen (nitrogen content in oil is typically 1000~5000 μL / L), meeting different detection accuracy requirements. The two detectors can automatically switch according to the detection target without manual intervention.

[0058] Low-concentration calibration mixed gas cylinder 15 and high-concentration calibration mixed gas cylinder 16 are set up to achieve calibration without standard oil, using dual-concentration multi-component mixed gas as calibration standard sample, avoiding the problems of preservation and contamination of standard oil sample.

[0059] The target component gas concentrations of the low-concentration standard gas in the low-concentration calibration mixed gas cylinder 15 are the gas concentrations under normal transformer operation conditions, specifically: H2=5μL / L, CH4=10μL / L, C2H2=1μL / L, C2H4=5μL / L, C2H6=5μL / L, CO=10μL / L, CO2=50μL / L, and the volume fractions of N2 and O2 are 79% and 21% respectively (simulating air component ratios).

[0060] The high-concentration standard gas in the high-concentration calibration mixed gas cylinder 16 has a target component gas concentration that is 50 times that of the low-concentration standard gas, specifically: H2=250μL / L, CH4=500μL / L, C2H2=50μL / L, C2H4=250μL / L, C2H6=250μL / L, CO=500μL / L, CO2=2500μL / L, while the N2 and O2 ratio remains unchanged, covering the concentration range during transformer faults (such as arc discharge and overheating) and seal failure.

[0061] Example 2

[0062] like Figure 3 As shown, this embodiment provides a detection method for dissolved gas and gas content detection devices in transformer oil based on Embodiment 1, including the following steps:

[0063] Step 1: Equipment preheating preparation

[0064] 1) Turn on the constant temperature chamber and set the temperature to 50℃ (the Ostwald coefficient of the oil is known at this temperature; wait for the temperature to stabilize (fluctuation ≤ 0.5℃, about 15 min).

[0065] 2) Connect the low-concentration calibration mixed gas cylinder 15 and the high-concentration calibration mixed gas cylinder 16 respectively, and check the pipeline sealing (pressure test: hold pressure at 1 atm for 5 min, pressure drop ≤0.01 atm).

[0066] 3) Start the mass spectrometry detection module 14, preheat for 30 min, and set the detection parameters: ion source temperature 200℃, electron energy 70 eV, scan rate 1000 u / s, and select the nine target component gases in Table 1 for the detection channel.

[0067] Step 2: Using a dual-concentration calibration mixed gas, establish the relationship curves between the concentration of each component gas and the mass spectrometry signal intensity.

[0068] 1) Open the solenoid valve in front of the low-concentration calibration mixed gas cylinder 15, and adjust the gas injection flow rate into the mass spectrometry detection module 14 to 5 mL / min. After the mass spectrometry signal of the mass spectrometry detection module 14 stabilizes (detection signal fluctuation ≤2%, approximately 2 minutes), record the mass spectrometry signal intensity of each component gas as follows: , , , , , , , , .

[0069] 2) Open the solenoid valve in front of the high-concentration calibration mixed gas cylinder 16, and adjust the gas injection flow rate into the mass spectrometry detection module 14 to 5 mL / min. After the mass spectrometry signal of the mass spectrometry detection module 14 stabilizes (detection signal fluctuation ≤2%, approximately 2 minutes), record the mass spectrometry signal intensity of each component gas as follows: , , , , , , , , .

[0070] 3) Since the concentrations of the calibration mixed gases in the low-concentration calibration mixed gas cylinder 15 and the high-concentration calibration mixed gas cylinder 16 are known, a 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, let the concentration of H2 component gas in the low-concentration calibration mixed gas be... The H2 component gas concentration of the high-concentration calibration mixed gas is The established relationship curve between the concentration of H2 component gas and the mass spectrometry signal intensity is shown in the figure below. Figure 4 As shown.

[0071] The method for establishing the relationship curves between the concentration of other component gases and the mass spectrometry signal intensity is the same as that for H2 component gas, and will not be repeated here.

[0072] The relationship between the concentration of each component gas and the mass spectrometry signal intensity is summarized as follows:

[0073] (1)

[0074] in, The mass spectrometry signal intensity of each component gas, To calibrate the response coefficients of the curve, The concentration of each component gas.

[0075] Step 3: Oil-gas film separation and mass spectrometry detection

[0076] Open valve 10, start peristaltic pump 11 to heat the oil sample to be tested and send it into oil-gas film separation module 13 for oil-gas separation until gas-liquid equilibrium is reached. Then turn on mass spectrometry detection module 14 to detect the mass spectrometry signal intensity of each component gas.

[0077] Step 4: Calculation of gas concentrations for each component

[0078] To solve the problem of peak overlap interference in mass spectrometry detection, it is necessary to identify the characteristic peaks, minor ion peaks, and interfering peaks of each target component gas. The specific parameters are shown in Table 1 below.

[0079] Table 1. Characteristic peaks, minor ion peaks, and interfering peak parameters of the target component gas.

[0080]

[0081] As shown in Table 1, the non-interfering components are: H2 (m / z 2), C2H6 (m / z 30), CO2 (m / z 44), and O2 (m / z 32). At m / z 28, there are overlapping peaks among N2, CO, C2H4, and C2H6, which interfere with each other; at m / z 16, there are overlapping peaks among CH4 and O2, which interfere with each other; and at m / z 26, there are overlapping peaks among C2H2 and C2H4, which interfere with each other.

[0082] 4.1 Calculation of the concentration of gaseous components without interference

[0083] For the non-interfering component gases H2: m / z 2, C2H6: m / z 30, CO2: m / z 44, and O2: m / z 32, the mass spectral signal intensity of each component gas is detected by the mass spectrometry detection module 14. The concentration of each component gas can be calculated by combining formula (1). .

[0084] 4.2 Calculation of Concentration of Interfering Component Gases

[0085] (1) Definition and calculation of response factor

[0086] The response factor is defined as follows:

[0087] (2)

[0088] in, The response signal of a pure, single-component standard gas X (X can be N2, O2, CO, CH4, C2H2, C2H4, or C2H6) at m / z Y is given. The concentration of a pure, single-component standard gas X, such as concentration. The minor ion peak N of pure nitrogen at a concentration of 100 μL / L + Response signal at m / z 14 (Y=14) If it is 1000, then the response factor Similarly, the response factors of each signal peak of other components are calculated, and the response factor is a fixed parameter for the same device.

[0089] Calculate the response factors of each component gas at each m / z peak. Single-component pure gases with concentrations of 500 μL / L (H2, CH4, C2H6, C2H4, C2H2, CO, CO2), 2000 μL / L (N2), and 2000 μL / L (O2) were introduced respectively. The characteristic peaks and secondary ion peaks of each component gas at different m / z were collected, and the response factors of each component gas at each m / z peak were calculated according to formula (2).

[0090] (2) Calculation of the concentration of C2H6 component gas

[0091] 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: .

[0092] (3) Calculation of the concentrations of N2, CO, and C2H4 components with overlapping peaks at m / z 28

[0093] At the mass spectrometry signal intensity of m / z 28, the characteristic peaks of N2, CO, C2H4, and C2H6 overlap. Therefore, in order to accurately calculate the concentration of each component gas, it is necessary to separate the mass spectrometry signal intensity of the characteristic peaks of N2, CO, C2H4, and C2H6 at m / z 28.

[0094] 1) Calculation of N2 component gas concentration

[0095] The mass spectrometry signal intensity at m / z 28 overlaps with the characteristic peaks of CO, C2H4, and C2H6 minor ion peaks. Therefore, to accurately calculate the concentration of the N2 component gas, it is necessary to separate the mass spectrometry signal intensity of the CO characteristic peak, C2H4 characteristic peak, and C2H6 minor ion peak at m / z 28. The specific method is as follows:

[0096] 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: .

[0097] 2) Calculation of CO component gas concentration

[0098] 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: .

[0099] 3) Calculation of the concentration of C2H4 component gas

[0100] 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: .

[0101] 5) Reverse verification

[0102] The mass spectral signal intensity of the N2 characteristic peak obtained in the above calculation process at m / z 28 The mass spectral signal intensity of the CO characteristic peak at m / z 28 The mass spectral signal intensity of the C2H4 characteristic peak at m / z 28 and the mass spectrometric signal intensity of the C2H6 minor ion peak at m / z 28. The sum of these four values ​​equals the total signal strength at m / z 28. That is:

[0103] (3)

[0104] (4) Calculation of the concentration of CH4 component gas with overlapping peaks at m / z 16

[0105] The mass spectrum signal intensity of the CH4 component gas at m / z 16 overlaps with that of the minor ion peak of O2. Therefore, to accurately calculate the concentration of the CH4 component gas, it is necessary to separate the mass spectrum signal intensity of the minor ion peak of O2 at m / z 16. The specific method is as follows:

[0106] The mass spectral signal intensity at m / z 32 was obtained using the characteristic peak of O2. Perform calibration, through The concentration of O2 was calculated. Its contribution to the mass spectrum signal intensity at m / z 16 is: Therefore, the mass spectral signal intensity of the CH4 component gas at m / z 16 is obtained through the total mass spectral signal intensity. and The difference is:

[0107] (4)

[0108] Then through The concentration of CH4 was calculated. .

[0109] (5) Calculation of the concentration of C2H2 component gas with overlapping peaks at m / z 26

[0110] The mass spectrum signal intensity of the C2H2 component gas at m / z 26 overlaps with that of the minor ion peak of C2H4. Therefore, to accurately calculate the concentration of the C2H2 component gas, it is necessary to separate the mass spectrum signal intensity of the minor ion peak of C2H4 at m / z 26. The specific method is as follows:

[0111] The concentration of C2H4 obtained from step (3) 3) ,pass The mass spectrum signal intensity of the minor ion peak of C2H4 at m / z 26 was calculated. Therefore, the mass spectrum signal intensity of the C2H2 component gas at m / z 26 is obtained through the total mass spectrum signal intensity. and The difference is:

[0112] (5)

[0113] Then through The concentration of C2H4 was calculated. .

[0114] Step 5: Concentration Conversion

[0115] Based on Henry's Law, the gas concentrations of each component calculated in step 4 are converted into gas concentrations in the oil sample. The conversion formula is as follows:

[0116] (6)

[0117] (7)

[0118] 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. This refers to the Ostwald coefficient. Table 2 below shows the Ostwald coefficient values ​​for each component gas in transformer oil at 50℃.

[0119] Table 2. Ostwald coefficients of various gas components in transformer oil at 50℃

[0120]

[0121] Step 6: Calculation of gas content

[0122] The gas content in transformer oil is the sum of the concentrations of nitrogen, oxygen, carbon monoxide, and carbon dioxide in the oil. Therefore, after converting the gas concentrations of each component into the gas concentrations in the oil sample in step 5, the gas content in the transformer oil can be obtained by summing them.

[0123] Example 3

[0124] An electronic device includes a memory and a processor, the memory being used to store a program that supports the processor in executing a detection method of the transformer oil dissolved gas and gas content detection device according to Embodiment 2, the processor being configured to execute the program stored in the memory.

[0125] Example 4

[0126] A storage medium storing a computer program, which, when executed by a processor, performs the steps of the detection method of the transformer oil dissolved gas and gas content detection device in Embodiment 2.

[0127] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

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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