Mass spectrum determination method and system for content of fault gas in transformer insulating oil

Abstract

The invention discloses a mass spectrum determination method and a mass spectrum determination system for fault gas content in transformer insulating oil, which comprises the following steps of: filling quantitative standard gas into a detection barrel, then injecting quantitative insulating oil to be detected into the detection barrel, standing for a set time period, and starting to circularly dissolve for set times, so that the dissolved gas of the insulating oil to be detected in the detection barrel is saturated; feeding the excess gas into a mass spectrometric detection unit for detection, and measuring the dissolved quantity mx of various fault gases; feeding the same amount of blank insulating oil into the detection barrel, feeding quantitative standard gas into the blank insulating oil until the gas content in the blank insulating oil is saturated, and measuring the dissolving amount mx'of various fault gases in the blank insulating oil; according to mx'and mx, the dissolving amount of the multiple fault gases of the to-be-detected insulating oil is calculated. Degassing rate correction can be avoided, and system errors are remarkably reduced. And absolute detection values of seven fault gas components in the insulating oil can be measured, so that a more accurate and reliable basis is provided for fault judgment. According to the method, a self-adaptive modeling strategy combining data calling and machine learning is adopted, an intelligent model capable of accurately predicting the optimal degassing cycle number is constructed, the optimal cycle dissolution number can be obtained in a self-adaptive mode according to the actual working condition, and therefore the solubility is remarkably improved, and meanwhile the overall efficiency and the resource utilization rate of the dissolution process are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transformer fault analysis, in particular to a method and system for mass spectrometric determination of fault gas content in transformer insulating oil. BACKGROUND

[0002] As an important insulating medium of power equipment (such as transformers, reactors, bushings, etc.), the content and change trend of internal dissolved gas components (such as H2, CH4, C2H2, CO, CO2, etc.) in insulating oil are the key basis for evaluating the running state and fault diagnosis of the equipment. At present, the method of "GB / T 17623-2017 Gas Chromatographic Determination of Dissolved Gas Components in Insulating Oil" is generally used for detection at home and abroad. This method realizes quantitative detection of dissolved gas by heating and shaking degassing combined with gas chromatography (GC) analysis. However, the existing technology has the following significant defects: the traditional heating and shaking degassing method requires long time constant temperature oscillation, and the degassing efficiency is affected by factors such as oil sample viscosity and temperature uniformity, resulting in low batch processing throughput, which is difficult to meet the timeliness requirements of large-scale state monitoring of power equipment. At the same time, compared with the valve switching, column replacement and temperature rising in chromatographic detection, mass spectrometric detection can quickly output values, greatly improving the detection rate. The degree of degassing cannot be determined in real time during the separation of oil and gas, which leads to the dependence of the absolute content of the seven characteristic gases on experience or formula correction. SUMMARY

[0003] The technical solution of the present application is used to solve how to directly invert the original solubility in oil without degassing rate correction.

[0004] The present application solves the above technical problems by the following technical means: The method for mass spectrometric determination of fault gas content in transformer insulating oil first fills a certain amount of standard gas into the detection barrel, then injects a certain amount of insulating oil to be tested into the detection barrel, and after standing for a certain period of time, the dissolved gas in the insulating oil to be tested in the detection barrel is saturated after circulating dissolution for a certain number of times. The excess gas is sent to the mass spectrometric detection unit for detection, and the dissolved amounts of a plurality of fault gases m x are measured; an equal amount of blank insulating oil is introduced into the detection barrel, and a certain amount of standard gas is introduced into the blank insulating oil until the gas content in the blank insulating oil is saturated, and the dissolved amounts of a plurality of fault gases m x ' in the blank insulating oil are measured; the dissolved amounts of a plurality of fault gases in the insulating oil to be tested are calculated according to m x ' and m x .

[0005] Further, the number of times of circulating dissolution is obtained by calling a database.

[0006] Further, the calling method of the database is: first, record the detection conditions, monitor the temperature and pressure Then, the first cycle of gas dissolution begins. After the first cycle of dissolution is completed, the gas is de-oiled and dehydrated in a cold trap and then sent to a mass spectrometry detection unit to analyze its gas composition. and the concentration of each gas component According to temperature ,pressure Gas components Concentration of each gas component after one cycle of dissolution By calling the function: Find the unique matching array from the database to determine the optimal number of iterations. ;in, express For database An array, This means that all conditions must be met. This indicates that a value matching the detected record needs to be found in the database. Completely identical array .

[0007] Furthermore, for cases where there is no corresponding insulating oil feature in the database, a method is used to obtain the number of iterations: first, the data detected after one iteration is normalized, and then the target array is calculated in the parameter space. With all arrays in the database Euclidean distance between them:

[0008] get The array in the database corresponding to the minimum value The corresponding optimal number of cycles for dissolution .

[0009] Furthermore, As the optimal number of dissolutions.

[0010] Furthermore, the database construction process is as follows: based on the control variable method, by establishing different temperatures... Different pressures Different component gases Different gas contents Standard oil sample, standard gas dissolved in the first cycle Under the condition, using the insulating oil with known characteristic dissolved gas concentration, taking a certain volume of insulating oil, adopting the circulating dissolved gas charging mode under different experimental conditions, after each cycle, the gas in the detection barrel is introduced into the mass spectrum detection unit after oil and water removal, the volume fraction of each component gas is detected, when the change value of the volume fraction of each component gas in the kth detection result compared with the (k-1) th detection result is less than the set value, it is determined that the Henry balance is reached, at this time, the cycle is stopped, otherwise the cycle is continued, and the k at this time is recorded as the optimal cycle dissolution times ; the data is normalized and stored in a database.

[0011] The application also provides a transformer insulating oil fault gas content mass spectrum determination system applied to the above method, comprising an oil inlet channel, an oil return channel, a circulating channel, an air inlet channel and a detection channel. The oil inlet channel comprises a first electromagnetic valve, a filter unit, a second electromagnetic valve, a quantitative barrel, a sixth electromagnetic valve and a detection barrel connected in series according to the flow direction of the insulating oil; the oil return channel comprises a fifth electromagnetic valve, a waste oil barrel, a third electromagnetic valve, an oil pump, a fourth electromagnetic valve and an oil return port connected in series from the outlet of the quantitative barrel; the circulating channel comprises an oil and water removal unit, a vacuum pump and an eleventh electromagnetic valve connected in series from the gas outlet of the detection barrel, and the eleventh electromagnetic valve is in communication with the air inlet of the detection barrel; the air inlet channel comprises a six-way valve and an eighth electromagnetic valve connected in series according to the air flow direction; the eighth electromagnetic valve is in communication with the air inlet of the detection barrel; and the detection channel comprises a ninth electromagnetic valve, a six-way valve, a tenth electromagnetic valve and a mass spectrum detection unit connected in series from the outlet of the vacuum pump.

[0012] Further, the gas outlet of the mass spectrum detection unit is also in communication with the detection barrel through a twelfth electromagnetic valve.

[0013] Further, a temperature control module for controlling the detection barrel is further included.

[0014] Further, during the circulating dissolution, the eleventh electromagnetic valve is opened and the remaining electromagnetic valves are closed, the vacuum pump is started, and the circulating dissolution is started, the gas forms microbubbles through the needle valve at the bottom of the detection barrel and passes through the oil layer from bottom to top, and the microbubble residence time is controlled to be greater than or equal to 5s.

[0015] The application has the following advantages: By adopting the method, the degassing rate correction can be avoided, the determination result can be directly traced to the national measurement standard, and the system error is significantly reduced. And the absolute detection value of seven component fault gases in the insulating oil can be measured, which provides more accurate and reliable basis for fault judgment. By adopting the one-time full component detection of mass spectrum, the analysis speed is greatly improved compared with the traditional chromatography, and the flux is improved by one order of magnitude. By adopting the adaptive modeling strategy combining data calling and machine learning, the intelligent model capable of accurately predicting the optimal degassing cycle number is constructed. The model has self-learning and dynamic adjustment capabilities, and can adaptively obtain the most suitable cycle dissolution number according to the actual working condition, so as to significantly improve the solubility, and effectively improve the overall efficiency and resource utilization of the dissolution process, thereby providing a reliable technical path for intelligent control and systematic upgrading of the degassing process. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a gas path diagram (before the valve is cut) of the method for determining the absolute content of fault gases in system insulating oil in embodiment 1 of the present application. Figure 2 It is a gas path diagram (after the valve is cut) of the method for determining the absolute content of fault gases in insulating oil in embodiment 2 of the present application. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0018] Embodiment 1 The embodiment discloses a transformer insulating oil fault gas content mass spectrum determination system, comprising an oil inlet passage, an oil return passage, a circulation passage, a gas inlet passage and a detection passage. As Figure 1As shown, the oil inlet passage sequentially includes a first electromagnetic valve, a filtering unit, a second electromagnetic valve, a dosing barrel, a sixth electromagnetic valve, and a detection barrel in series according to the flow direction of the insulating oil; the oil return passage sequentially includes a fifth electromagnetic valve, a waste oil barrel, a third electromagnetic valve, an oil pump, a fourth electromagnetic valve, and an oil return port in series from the outlet of the dosing barrel; the circulation passage includes a deoiling and dewatering unit and a vacuum pump in series from the exhaust port of the detection barrel, and the eleventh electromagnetic valve is in communication with the air inlet of the detection barrel; the air inlet passage sequentially includes a six-way valve and an eighth electromagnetic valve in the airflow direction; the eighth electromagnetic valve is in communication with the air inlet of the detection barrel; the detection passage includes a ninth electromagnetic valve, a six-way valve, a tenth electromagnetic valve, and a mass spectrometric detection unit in series from the outlet of the vacuum pump. The exhaust port of the mass spectrometric detection unit is also in communication with the detection barrel through a twelfth electromagnetic valve. The exhaust port of the mass spectrometric detection unit is also provided with a thirteenth electromagnetic valve. A temperature control module for controlling the detection barrel is further included.

[0019] Embodiment 2 Since the seven fault characteristic gases in the insulating oil are H2, CH4, C2H2, CO, CO2, C2H4, and C2H6, these seven gases cover typical products of different fault modes such as overheating, discharge, and electric arc, and are fingerprint components for judging the type and severity of internal transformer faults. From the macroscopic thermodynamic point of view, they are all low-concentration (ppm level) dilute gas, which can be approximately regarded as an “infinite dilution system”. In the dilute solution range, the solubility of each gas is mainly determined by its own Ostwald coefficient K i , and the activity coefficient interference between them is very small. The Henry / Ostwald model commonly used in the laboratory is processed according to “single-component independent equilibrium”, and the repeatability error is generally ≤2%, that is, after one kind of gas is saturated, it does not affect the dissolution of other gases.

[0020] Therefore, based on the transformer insulating oil fault gas content mass spectrometric determination system of embodiment 1, this embodiment introduces the specific determination method. The overall idea is to first construct a cycle number database containing various types of insulating oil; based on the database, during specific detection, a certain amount of standard gas is first filled into the detection barrel, then a certain amount of insulating oil to be detected is injected into the detection barrel, and after standing for a certain period of time, the insulating oil to be detected in the detection barrel is dissolved for a certain number of times to make the insulating oil to be detected in the detection barrel saturated, and the excess gas is sent to the mass spectrometric detection unit for detection, and the dissolution amount m x of the plurality of fault gases is measured. x An equal amount of blank insulating oil is introduced into the detection barrel, and a certain amount of standard gas is introduced into the blank insulating oil until the gas content in the blank insulating oil is saturated, and the dissolution amount m x of the plurality of fault gases in the blank insulating oil is measured. x The dissolution amount of the plurality of fault gases in the insulating oil to be detected is calculated according to m

[0021] The specific process of measuring the amount of dissolution is as follows: if it is determined that the detection barrel reaches equilibrium, the detection result of the ith time is recorded, and the volume fraction of each of the seven fault gases is measured , wherein the volume fraction of nitrogen is .

[0022] The total amount of dissolution of the seven fault mixed gases (H2, CH4, C2H2, CO, CO2, C2H4, C2H6) is:

[0023] The dissolution amount m of each of the seven fault mixed gases x is:

[0024] Then, the solubility is back calculated. An equal amount of blank insulating oil is introduced into the detection barrel, the dissolution step is repeated, the mass of the mixed gas that can be completely dissolved by the blank insulating oil under the same conditions is measured as m2, and the dissolution amount of each of the seven fault mixed gases in the blank insulating oil is calculated as The dissolution amount m of the fault gas contained in the insulating oil to be measured g is:

[0025] When calculating the current solubility C, the density value of the seven-component fault gas under standard conditions (0°C, 1 atm) needs to be converted , and the standard density formula can be derived based on the ideal gas state equation and the standard molar mass:

[0026] wherein: — is the standard density of the fault gas, with a unit of g / L; P— is the standard atmospheric pressure, 1 atm; — is the molar mass of the fault gas, with a unit of g / mol; T— is the standard temperature, 273.15 K; According to the content about the dissolution coefficient in the standard GB / T 17623-2017 “Gas Chromatographic Determination of Insulating Oil Dissolved Gas Component Content”, the dissolution coefficient of different characteristic gases can be obtained from the table . Thus, the solubility of the dissolved gas in the insulating oil is calculated as:

[0027]

[0028] wherein, To determine the test volume of the insulating oil sample, To detect the gas detection volume, Let be the gas concentration of component i. Due to the solubility coefficient in the standard... The test is conducted at 70℃, so a gas volume of [missing information] is required. and detection of insulating oil sample volume Gas volume after temperature and pressure correction:

[0029] Corrected insulating oil volume .in The temperature recorded by the system during the detection. The pressure recorded by the system during the test will be corrected. , Substitution Calculate the corrected C.

[0030] In this embodiment, the database is accessed as follows: First, the detection conditions are recorded, and the temperature in the detection tank is monitored using temperature and pressure sensors. and pressure Then, the first cycle of gas dissolution begins. After the first cycle of dissolution is completed, the gas is de-oiled and dehydrated in a cold trap and then sent to a mass spectrometry detection unit to analyze its gas composition. and the concentration of each gas component According to temperature ,pressure Gas components Concentration of each gas component after one cycle of dissolution By calling the function: Find the unique matching array from the database to determine the optimal number of iterations. ;in, express For database An array, This means that all conditions must be met. This indicates that a value matching the detected record needs to be found in the database. Completely identical array .

[0031] For cases where no corresponding insulating oil feature is found in the database, the following method is used to obtain the number of iterations: First, the data detected after one iteration is normalized, and then the target array is calculated in the parameter space. With all arrays in the database Euclidean distance between them:

[0032] get The array in the database corresponding to the minimum value The corresponding optimal number of cycles for dissolution As a compensation mechanism, to prevent insufficient predicted number of cycles, the system will automatically add 1 to the optimal number of cycles at the nearest point, thereby ensuring a reliable dissolution effect. The optimal number of dissolutions was determined by the following parameters: GC-MS mass spectrometer inlet gas flow rate of 0.5–3 ml / min, and vacuum level of 10. -5 The detection rate is 20-40ms, so the amount of gas consumed in each detection is extremely small and can be ignored.

[0033] The database was constructed as follows: based on the control variable method, by establishing databases at different temperatures... Different pressures Different component gases Different gas contents Standard oil sample, standard gas dissolved in the first cycle To determine the optimal number of cyclic dissolution cycles, a database was established. Insulating oil with known characteristic dissolved gas concentrations was used. A 3 / 4V volume of insulating oil was used, and under different experimental conditions, a cyclic dissolution and gas-filling method was employed. After each cycle, the gas in the detection container was deoiled and dehydrated before being introduced into a mass spectrometer detection unit to detect the volume fraction of each gas component. Henry's equilibrium was considered reached when the change in the volume fraction of each gas component in the k-th detection result compared to the (k-1)-th cycle was less than 1%, at which point the cycle was immediately stopped; otherwise, the cycle continued. The value of k at this point was recorded as the optimal number of cyclic dissolution cycles. After standardizing the data, store it in the dataset to prepare for subsequent interface calls and function implementation. This will establish the database, as shown in the table below.

[0034] Table 1 Dataset

[0035] A database can be expressed as ,in It is an array, and each array contains 6 data points (temperature). ,pressure Gas components Different gas contents Standard oil sample, standard gas dissolved in the first cycle Optimal number of iterations ).Right now: .

[0036] Calculate the amount of solubility If it is determined that the test chamber has reached equilibrium, the result of the i-th test is recorded, and the volume fraction of each of the seven fault gases is measured. wherein the volume fraction of nitrogen is .

[0037] The total amount of dissolution of the seven fault mixed gases is :

[0038] The amount of dissolution of each of the seven fault mixed gases m x is:

[0039] It should be noted that before formal detection, the system needs to be prepared for pre-detection, specifically: (1) Detect the seven-component fault gas standard gas with N2 as the background gas, start the vacuum pump, open electromagnetic valves 1, 2, 6, 9, and vacuumize the oil inlet and detection barrel. Turn on the temperature control module of the detection barrel, and target the preheating and stabilization of the barrel temperature to 50℃. At the same time, measure the volume fraction of each of the seven-component fault gas, open electromagnetic valves 10 and 13, and pass the standard gas through six-way valve 4-3 into the mass spectrometry detection unit to measure the volume fraction of each of the seven-component fault gas (wherein x is H2, CH4, C2H2, CO, CO2, C2H4, C2H6 respectively), wherein the volume fraction of nitrogen is .

[0040] (2) Inlet gas sample. In order to provide preliminary gas pressure in the detection barrel, a certain amount of standard gas should be filled into the detection barrel in advance to avoid the precipitation of dissolved gas due to too low pressure in the barrel when the oil sample is introduced. Switch the six-way valve (such as Figure 2 ) to make the standard gas pass through six-way valve 4-5 into the detection barrel. Slowly introduce the sample during sampling, and after the temperature is stabilized, read the absolute pressure in the detection barrel to 0.05 MPa, and stop sampling. At this time, the mass of the standard gas entering the detection barrel can be calculated as:

[0041]

[0042]

[0043] wherein: m - the mass of the standard gas, unit g; ρ - the density of the standard gas, unit g / L; V - the volume of the standard gas, unit L; P - the pressure of the standard gas after sampling, unit Pa, M - the average molar mass of the standard gas, unit g / mol; R - the gas constant; T - the temperature of the temperature after the standard gas enters the detection barrel, unit k; - the molar mass of the specific gas, such as , etc. in g / mol; - the volume fraction of the specific gas, such as , etc.; (3) Oil sample. Open electromagnetic valves 1, 2, 3, 4, 5, and 6, and pass the insulating oil through the filter unit for preliminary filtration to ensure that there is no solid impurity in the insulating oil, and then pass the insulating oil through the quantitative barrel to take a certain amount of insulating oil, which is 3 / 4V of the detection barrel capacity, that is, . Open electromagnetic valve 6 to pass the filtered insulating oil into the detection barrel, and pass the waste oil through the oil pump to return to the oil return port. After the sample is added, it is left to stand, and when the temperature of the detection barrel is stable to the set value, the next step is performed.

[0044] By using the method of the embodiment, the degassing rate correction can be avoided, the determination result can be directly traced to the national measurement standard, the system error is significantly reduced, and the absolute detection value of seven component fault gases in the insulating oil can be measured, which provides a more accurate and reliable basis for fault judgment. By using one-time full-component detection by mass spectrometry, the analysis speed is greatly improved compared with traditional chromatography, and the flux is improved by one order of magnitude. By using a self-adaptive modeling strategy combining data calling and machine learning, an intelligent model capable of accurately predicting the optimal degassing cycle number is constructed. The model has self-learning and dynamic adjustment capabilities, and can adaptively obtain the most suitable cycle dissolution number according to the actual working condition, so as to significantly improve the solubility while effectively improving the overall efficiency and resource utilization of the dissolution process, thereby providing a reliable technical path for intelligent control and systematic upgrading of the degassing process.

[0045] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, 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 mass spectrometry method for determining the content of fault gases in transformer insulating oil, characterized in that, First, a fixed amount of standard gas is introduced into the test chamber. Then, a fixed amount of the insulating oil to be tested is injected into the test chamber. After standing for a set time, the mixture is circulated and dissolved a set number of times until the dissolved gas in the insulating oil in the test chamber reaches saturation. The excess gas is then sent to a mass spectrometry detection unit for detection, and the dissolved amount m of various fault gases is measured. x Take an equal amount of blank insulating oil and pass it into the test container. Then, introduce a measured amount of standard gas into the blank insulating oil until the oil is saturated with gas. Measure the solubility (m) of various fault gases in the blank insulating oil. x ';According to m x 'and m x Calculate the solubility of various fault gases in the insulating oil to be tested.

2. The mass spectrometry method for determining the fault gas content in transformer insulating oil according to claim 1, characterized in that, The number of cycles for dissolving is obtained by calling the database.

3. The mass spectrometry method for determining the fault gas content in transformer insulating oil according to claim 2, characterized in that, The database is accessed as follows: First, the detection conditions are recorded, and the temperature in the detection tank is monitored using temperature and pressure sensors. and pressure Then, the first cycle of gas dissolution begins. After the first cycle of dissolution is completed, the gas is de-oiled and dehydrated in a cold trap and then sent to a mass spectrometry detection unit to analyze its gas composition. and the concentration of each gas component According to temperature ,pressure Gas components Concentration of each gas component after one cycle of dissolution By calling the function: Find the unique matching array from the database to determine the optimal number of iterations. ;in, express For database An array, This means that all conditions must be met. This indicates that a value matching the detected record needs to be found in the database. Completely identical array .

4. The mass spectrometry method for determining the fault gas content in transformer insulating oil according to claim 2, characterized in that, For cases where no corresponding insulating oil feature is found in the database, the following method is used to obtain the number of iterations: First, the data detected after one iteration is normalized, and then the target array is calculated in the parameter space. With all arrays in the database Euclidean distance between them: get The array in the database corresponding to the minimum value The corresponding optimal number of cycles for dissolution .

5. The mass spectrometry method for determining the fault gas content in transformer insulating oil according to claim 4, characterized in that, Will As the optimal number of dissolutions.

6. The mass spectrometry method for determining the fault gas content in transformer insulating oil according to any one of claims 1 to 5, characterized in that, The database was constructed as follows: based on the control variable method, by establishing different temperatures... Different pressures Different component gases Different gas contents Standard oil sample, standard gas dissolved in the first cycle Under the given conditions, insulating oil with known characteristic dissolved gas concentrations was used. A certain volume of insulating oil was taken and subjected to cyclic dissolution and gas filling under different experimental conditions. After each cycle, the gas in the detection container was deoiled and dehydrated before being introduced into the mass spectrometry detection unit to detect the volume fraction of each gas component. When the change in the volume fraction of each gas component in the k-th detection result compared to the (k-1)-th result was less than the set value, Henry's equilibrium was determined to have been reached, and the cycle was immediately stopped; otherwise, the cycle continued. The value of k at this point was recorded as the optimal number of dissolution cycles. The data is then standardized and stored in the database.

7. A mass spectrometry system for determining the content of fault gases in transformer insulating oil using the method described in any one of claims 1 to 6, characterized in that, This includes the oil inlet passage, oil return passage, circulation passage, air intake passage, and detection passage; The oil inlet path includes, in sequence according to the direction of insulating oil, a first solenoid valve (1), a filter unit, a second solenoid valve (2), a metering tank, a sixth solenoid valve (6), and a detection tank connected in series; the oil return path includes, in sequence from the outlet of the metering tank, a fifth solenoid valve (5), a waste oil tank, a third solenoid valve (3), an oil pump, a fourth solenoid valve (4), and an oil return port connected in series; the circulation path includes, in sequence from the exhaust port of the detection tank, an oil and water removal unit, a vacuum pump, and an eleventh solenoid valve (11), the eleventh solenoid valve (11) being connected to the air inlet of the detection tank; the air inlet path includes, in sequence according to the airflow direction, a six-way valve (6) and an eighth solenoid valve (8); the eighth solenoid valve (8) being connected to the air inlet of the detection tank; the detection path includes, in sequence from the outlet of the vacuum pump, a ninth solenoid valve (9), a six-way valve, a tenth solenoid valve (10), and a mass spectrometry detection unit connected in series.

8. The mass spectrometry system for determining the content of fault gases in transformer insulating oil according to claim 7, characterized in that, The exhaust port of the mass spectrometer detection unit is also connected to the detection tank through the twelfth solenoid valve (12).

9. The mass spectrometry system for determining the content of fault gases in transformer insulating oil according to claim 7 or 8, characterized in that, It also includes a temperature control module for controlling the testing tank.

10. The mass spectrometry system for determining the content of fault gases in transformer insulating oil according to claim 7 or 8, characterized in that, During the cyclic dissolution, open the eleventh solenoid valve (11), close the other solenoid valves, start the vacuum pump, and begin the cyclic dissolution. The gas forms microbubbles through the needle valve at the bottom of the detection tank and passes through the oil layer from bottom to top; control the residence time of the microbubbles to ≥5s.

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