Gassing equipment for measuring gas production of insulating oil under electrothermal coupling field

Abstract

The utility model relates to gassing equipment for measuring gas production of insulating oil under an electrothermal coupling field, which comprises a gassing tank, a high-voltage electrode, a circulating pump and an oil bath tank, the gassing tank is communicated with the circulating pump, and the high-voltage electrode is embedded in the gassing tank and connected with a high-voltage power supply; the circulating pump is immersed in the oil bath; an aluminum foil is arranged on the outer layer of the gassing tank, so that the gassing tank is wrapped by the aluminum foil to form an outer electrode, and then the outer electrode is grounded through a high-voltage negative electrode jointing clamp. The gassing equipment for measuring gas production of insulating oil under the electrothermal coupling field combines an electric field and a thermal field to realize flexible and accurate temperature and voltage control of a test environment, is close to actual operation and accurate in measurement, and improves the accuracy and comprehensiveness of measurement of gas production characteristics of transformer oil; important technical support and solution are provided for improving the performance of the insulating oil of the transformer, and the gas production rule is disclosed.

Description

Technical Field

[0001] The utility model belongs to the technical field of high-voltage insulating oil performance evaluation, and particularly relates to a gas evolution device for measuring insulating oil gas production under an electro-thermal coupling field. Background Technique

[0002] As environmental protection awareness has become a worldwide consensus, developing insulating oils that meet environmental protection requirements has become a new research topic. Natural ester (plant) insulating oil is a high-flashpoint, environmentally friendly liquid dielectric. Its flash point exceeds 300°C, the natural degradation rate in 28 days reaches 95%, and the power frequency breakdown voltage can exceed 70 kV. The main physical and chemical, electrical performance indicators can meet the requirements of power transformer oils. Compared with mineral insulating oil, the dielectric constant of natural ester insulating oil is closer to that of insulating paper, and the electric field distribution between oil and paper in the natural ester oil-paper insulation system in an alternating current electric field is more uniform, effectively extending the life of insulating paper and reducing the total life cycle cost of transformers. It has gradually become the focus of research in the field of insulating oils. Considering environmental pollution, fire safety, health hazard risks, and the need to reduce the volume of transformers, natural ester insulating oil is an important liquid dielectric that can replace mineral oil in the next generation.

[0003] However, due to the differences between natural ester plant insulating oil and mineral oil, traditional operation and maintenance experience is no longer applicable. Currently, there is still a lack of a large amount of test data and operation data for the stray gas generation law of natural ester plant insulating oil. In recent years, due to the wide application of oil-immersed transformers, domestic and foreign scholars have also carried out relevant research on the gas production characteristics of different insulating oils. However, the stray gas test environment in existing literature is basically only at low temperatures (120°C and below), with only thermal stress, which is quite different from the actual transformer operating conditions. There is a lack of gas production characteristic data of plant insulating oil under electro-thermal combined conditions, and the influence of actual operating conditions: electric field and fluidity is not considered, and the research is one-sided. Currently, there is still a lack of a large amount of test data and operation data for the gas production law of vegetable oil transformers.

[0004] The existing limitations are as follows: 1. Single test conditions: One-sided consideration, without considering the actual operating conditions: the influence of electric field and fluidity. 2. Lack of electro-thermal gas production data: Only the action of electrical stress or thermal stress alone, lacking test data under the combined and synergistic action of electro-thermal stress. The latest operation data shows that there is a phenomenon of stray gas in insulating oil, especially for natural ester insulating oil, the data of hydrogen and ethane are significantly high. Therefore, it is necessary to study the cracking and gas production mechanism of insulating oil under electro-thermal combined conditions for plant insulating oil, laying a foundation for improving the operating voltage and capacity of vegetable oil transformers, ensuring the stable operation of vegetable oil transformers, and improving the fault diagnosis methods and systems of vegetable oil transformers.

[0005] In order to be as close as possible to the actual internal environment of the transformer during operation, during testing, it is required that the vegetable insulating oil can be pressurized and heated simultaneously, and the voltage and temperature can be effectively controlled. Since there are natural circulation and forced circulation inside the transformer, the oil sample in the electro-thermal combined stress and circulating flow test platform also needs to be forced to circulate. Gas production laws under the electro-thermal coupling field of vegetable oil transformers are studied through gas chromatography, as well as the influence of normal operating voltage on gas production laws of natural ester insulating oil.

[0006] Therefore, it is necessary to design a gas evolution device for measuring gas production of insulating oil under an electro-thermal coupling field, which fully considers the actual operating environment of oil-immersed transformers. This device combines an electro-thermal coupling field and a flow device, making the obtained gas production data more real and comprehensive. Summary of the Utility Model

[0007] The purpose of the present utility model is to provide a gas evolution device for measuring gas production of insulating oil under an electro-thermal coupling field, which fully considers the actual operating environment of oil-immersed transformers. This device combines an electro-thermal coupling field and a flow device, making the obtained gas production data more real and comprehensive.

[0008] To solve the above technical problems, the technical solution adopted by the present utility model is that the gas evolution device for measuring gas production of insulating oil under an electro-thermal coupling field includes a gas evolution cell, a high-voltage electrode, a circulation pump, and an oil bath. The gas evolution cell is connected to the circulation pump, and the high-voltage electrode is embedded in the gas evolution cell and connected to a high-voltage power supply; the circulation pump is immersed in the oil bath.

[0009] Adopting the above technical solution, in order to fully consider the actual operating environment of oil-immersed transformers, the gas evolution cell and the oil bath are combined. While pressurizing with the high-voltage electrode, the oil bath is used for heating, realizing simultaneous pressurization and heating of vegetable insulating oil, and effectively controlling the voltage and temperature; since there are natural circulation and forced circulation inside the transformer, a circulation pump is set to make the oil sample in this gas evolution device forced to circulate, making the obtained gas production data more real and comprehensive. This device combines an electric field and a thermal field to flexibly and accurately control the test environment of temperature and voltage, approaching actual operation, with accurate measurement, improving the accuracy and comprehensiveness of the determination of the gas production characteristics of transformer oil. This technological breakthrough provides an important platform for improving the performance of insulating oil and is expected to play an important role in the operation and maintenance of transformers.

[0010] Preferably, an aluminum foil is provided on the outer layer of the gas evolution cell, so that the gas evolution cell is wrapped by the aluminum foil to form an outer electrode, and then grounded through a high-voltage negative electrode terminal clamp. An aluminum foil is provided on the outer layer of the gas evolution cell. The gas evolution cell is wrapped by the aluminum foil, and then a grounding end is formed through the high-voltage negative electrode terminal clamp, that is, an internal and external field strength difference is formed by the 10 kV plug of the high-voltage wire and the negative electrode clamp.

[0011] Preferably, the circulation pump and the grounding wire plug are fixedly combined through a gas evolution cell support plate and immersed in the oil bath.

[0012] Preferably, the gas evolution cell is provided with an upper inlet and a lower outlet. Both the upper inlet and the lower outlet of the gas evolution cell are connected to the circulation pump through rubber hoses to form a closed loop for circulating flow. The circulation pump is set to ensure sufficient circulation of the oil sample, and the flow rate can reach 345.2 m / s. At the same time, the gas evolution device is made closer to the actual operation inside the transformer, with rapid adjustment and response, which can meet the requirements of the electro-thermal coupling field and fluidity test of the plant insulating oil in this article.

[0013] Preferably, the high-voltage electrode is connected to the high-voltage power supply through a high-voltage wire plug. The high-voltage electrode is nested with the high-voltage wire electrode through the high-voltage wire plug, and then forms an electric field loop with the grounding wire plug through the high-voltage negative electrode terminal clamp of the gas evolution cell.

[0014] Preferably, a support is provided in the oil bath for fixing the gas evolution cell and the high-voltage wire electrode.

[0015] Preferably, the oil bath is a glass oil bathtub, which is provided with a constant temperature controller and a stirring device inside. The stirring device is provided to maintain the uniformity of the oil bath temperature.

[0016] Preferably, a platinum resistance thermometer is provided inside the oil bath as a temperature measuring element. The maximum temperature of 200 °C can be achieved by the oil bath heating method, and high-precision constant temperature control is realized with a precision platinum resistance thermometer as the temperature measuring element.

[0017] Preferably, the capacity of the gas evolution cell is 50 mL; the inner diameter of the rubber hose is 4 mm, the flow rate of the circulation pump is 260 mL per minute, and the maximum flow velocity is 345.2 m / s.

[0018] Preferably, an outgassing device for measuring the gas production of insulating oil under the electro-thermal coupling field is used to build an electro-thermal combined stress and circulating flow test platform. The high-voltage electrode in the electro-thermal combined stress and circulating flow test platform is made of stainless steel and polished on the surface. The outer diameter of the high-voltage electrode is 46.7 mm, and the inner diameter of the pipeline of the outgassing cell is 51.8 mm. The high-voltage electrode is inserted into the outgassing cell so that the oil sample is distributed within a 2-mm gap of the electrode. The maximum voltage of the voltage generator is 12 kV. According to the electric field strength = voltage / distance, the maximum electric field strength of 6 kV / mm is achieved. The model of the high-voltage generator is JXQ2013A, which can control the test voltage within 10 kV ± 2%. And the difference between the peak factor (the ratio of the peak value to the average effective value) of the test voltage and the peak factor of the sine wave shall not be greater than +5%. The step-up transformer works based on the principle of magnetic field induction of the coil, while the voltage multiplier circuit uses components such as capacitors and diodes to charge and discharge alternately, thereby gradually increasing the voltage. This electro-thermal combined stress and circulating flow test platform for the plant insulating oil transformer can simultaneously pressurize and heat the sample oil, and the maximum temperature of 200 °C can be achieved by means of oil bath heating. The maximum voltage can reach 12 kV. At the same time, with the inner diameter of the outgassing cell pipeline being 51.8 mm and the outer diameter of the electrode being 46.7 mm, the maximum electric field strength of 6 kV / mm can be achieved. In addition, a circulating pump device is added to ensure the full circulation of the oil sample, and the flow rate can reach 345.2 m / s. The entire electro-thermal combined stress and circulating flow test platform is closer to the actual operation inside the transformer, with rapid adjustment and response, and can meet the requirements of the electro-thermal coupling field and fluidity tests of plant insulating oil.

[0019] Compared with the prior art, the beneficial effects of the present utility model are as follows: The outgassing device for measuring the gas production of insulating oil under the electro-thermal coupling field combines the electric field and the thermal field to realize an environment with flexible and accurate control of temperature and voltage for testing, which is close to the actual operation, with accurate measurement, improving the accuracy and comprehensiveness of the determination of the gas production characteristics of transformer oil, providing important technical support and solutions for the improvement of the performance of transformer insulating oil, and revealing the gas production law. Under the current situation where the stray gas data of plant insulating oil transformers is limited and the gas production law of stray gases is lacking, it has important theoretical significance and guiding value for establishing a dissolved gas diagnosis method in plant insulating oil and comprehensively and accurately evaluating the operation and maintenance status of transformers. Specifically:

[0020] (1) Comprehensively considering the actual operation environment: The outgassing device for measuring the gas production of insulating oil under the electro-thermal coupling field takes into account the requirements of the actual operation environment of oil-immersed transformers, introduces a flow device, enabling the gas to flow more smoothly during the test, ensuring that the test data is more real and reliable;

[0021] (2) Gas evolution equipment under electro-thermal coupling field: The gas evolution equipment for measuring the gas production of insulating oil under electro-thermal coupling field can adapt to the electro-thermal coupling field. By combining the electric field and the thermal field, it can flexibly and accurately control the test environment of temperature and voltage, so as to approach the actual operation and measurement accuracy, and improve the accuracy and comprehensiveness of the determination of the gas production characteristics of transformer oil;

[0022] (3) Applicable to various places: Compared with other large-capacity and large-scale equipment simulating electro-thermal environment, the gas evolution equipment for measuring the gas production of insulating oil under electro-thermal coupling field has a small floor area, a low requirement for the capacity of insulating oil, is easy to operate, and can subsequently measure the types and contents of dissolved gases in oil by gas chromatography method according to GB / T 17623-2017. It is efficient and convenient, and can be applied to laboratories in universities, testing centers in production enterprises and various professional testing institutions. Brief Description of the Drawings

[0023] Figure 1 It is the specific structure diagram of the gas evolution equipment for measuring the gas production of insulating oil under electro-thermal coupling field of the present utility model; wherein, 1 - gas evolution pool; 2 - high-voltage electrode; 3 - high-voltage negative electrode terminal clamp; 4 - high-voltage wire plug; 5 - high-voltage wire electrode; 6 - grounding wire plug; 7 - bracket; 8 - circulation pump; 9 - gas evolution pool support plate; 10 - aluminum foil; 11 - rubber tube; 12 - oil bath;

[0024] Figure 2 It is the content and relative proportion of dissolved gases in insulating oil at different field strengths and different times at 80°C when using the gas evolution equipment for measuring the gas production of insulating oil under electro-thermal coupling field of the present utility model to build an electro-thermal combined stress and circulating flow test platform for testing. Among them, (a) is the gas production content of NE insulating oil in Specific Example 1 (0 kV / mm), (b) is the gas production content of NE insulating oil in Specific Example 2 (2 kV / mm), (e) is the gas production content of NE insulating oil in Specific Example 3 (4 kV / mm), (f) is the gas production content of NE insulating oil in Specific Example 4 (5 kV / mm), (c) is the change of the relative proportion of characteristic gases of NE insulating oil in Specific Example 1 (0 kV / mm) with time, (b) is the change of the relative proportion of characteristic gases of NE insulating oil in Specific Example 2 (2 kV / mm) with time, (e) is the change of the relative proportion of characteristic gases of NE insulating oil in Specific Example 3 (4 kV / mm) with time, (f) is the change of the relative proportion of characteristic gases of NE insulating oil in Specific Example 4 (5 kV / mm) with time;

[0025] Figure 3For the present utility model, when using the gas evolution device for measuring insulating oil gas production under the electro-thermal coupling field of the present utility model to build an electro-thermal combined stress and cyclic flow test platform for testing, the dissolved gas content and relative ratio in the insulating oil at different field strengths and different times at 80°C are measured; among them, (a) is the gas production content of NE insulating oil in Specific Embodiment 5 (0 kV / mm), (b) is the gas production content of NE insulating oil in Specific Embodiment 6 (2 kV / mm), (c) is the variation of the relative ratio of characteristic gases of NE insulating oil in Specific Embodiment 5 (0 kV / mm) with time, and (d) is the variation of the relative ratio of characteristic gases of NE insulating oil in Specific Embodiment 6 (2 kV / mm) with time. Detailed implementation mode

[0026] The following further describes the technical solution with reference to the accompanying drawings.

[0027] Example: As Figure 1As shown in the figure, the gas evolution device for measuring insulating oil gas production under the electro-thermal coupling field includes a gas evolution cell 1, a high-voltage electrode 2, a circulation pump 8, and an oil bath 12. The gas evolution cell 1 is connected to the circulation pump 8, and the high-voltage electrode 2 is embedded in the gas evolution cell 1 and connected to a high-voltage power supply. The circulation pump 8 is immersed in the oil bath 12. An aluminum foil 10 is provided on the outer layer of the gas evolution cell 1, so that the outer electrode is formed by wrapping the gas evolution cell 1 with the aluminum foil 10, and then grounded through the high-voltage negative electrode terminal clamp 3. An aluminum foil 10 is provided on the outer layer of the gas evolution cell 1, and the outer electrode is formed by wrapping the gas evolution cell 1 with the aluminum foil 10 and the grounding terminal is formed through the high-voltage negative electrode terminal clamp 3, that is, the internal and external field strength differences are formed by the 10 kV plug of the high-voltage wire and the negative electrode clamp. The circulation pump 8 and the grounding wire plug 6 are fixedly combined through the gas evolution cell support plate 9 and immersed in the oil bath 12. The gas evolution cell 1 is provided with an upper inlet 101 and a lower outlet 102. Both the upper inlet 101 and the lower outlet 102 of the gas evolution cell 1 are connected to the circulation pump 8 through rubber hoses 11 to form a closed loop for circulating flow. The circulation pump 8 is provided to ensure sufficient circulation of the oil sample, and the flow rate can reach 345.2 m / s. At the same time, the gas evolution device is closer to the actual operation inside the transformer, with rapid adjustment and response, and can meet the requirements of the electro-thermal coupling field and fluidity test of the plant insulating oil in this article. The high-voltage electrode 2 is connected to the high-voltage power supply through a high-voltage wire plug 4. The high-voltage electrode 2 is nested with a high-voltage wire electrode 5 through a high-voltage wire plug 4, and then an electric field circuit is formed through the high-voltage negative electrode terminal clamp 3 of the gas evolution cell and the grounding wire plug 6. A support 7 is provided in the oil bath for fixing the gas evolution cell 1 and the high-voltage wire electrode 5. The oil bath 12 is a glass oil bathtub, which is provided with a constant temperature controller and a stirring device. The stirring device is provided to maintain the uniformity of the oil bath temperature. A metal platinum resistance is provided in the oil bath 12 as a temperature measuring element. The maximum temperature of 200 °C can be achieved by the oil bath heating method, and high-precision constant temperature control is achieved with a precision metal platinum resistance as the temperature measuring element. The capacity of the gas evolution cell 1 is 50 mL. To match the standard GB / T 17623-2017, the gas chromatography method can be used to measure the types and contents of dissolved gases in the oil. The inner diameter of the rubber hose 11 is 4 mm, the flow rate of the circulation pump 8 is 260 mL per minute, and the flow velocity = flow rate / area, so the maximum flow velocity can be obtained: the maximum flow velocity is 345.2 m / s. The maximum flow velocity is 345.2 m / s.

[0028] The gasification equipment for measuring the gas production of insulating oil under the electrothermal coupling field is used to build an electrothermal combined stress and cyclic flow test platform, specifically: the high-voltage electrode 2 in the electrothermal combined stress and cyclic flow test platform is made of stainless steel and has a polished surface; the outer diameter of the high-voltage electrode 2 is 46.7mm, and the inner diameter of the pipeline of the gasification pool 1 is 51.8mm; the high-voltage electrode 2 is inserted into the gasification pool 1, so that the oil sample is distributed in the 2mm gap between the electrodes, and the maximum voltage of the voltage generator is 12kV. According to the field strength = voltage / distance, the maximum field strength is 6kV / mm. The high-voltage generator model is JXQ2013A, which can control the test voltage at 10kV+2%, and the difference between the peak factor (ratio of peak value to average effective value) of the test voltage and the peak factor of the sine wave shall not be greater than +5%. The transformer works on the magnetic field induction principle of the coil, and the voltage multiplier circuit uses components such as capacitors and diodes to alternately charge and discharge, thereby gradually increasing the voltage. This electric-thermal combined stress and circulating flow test platform for vegetable insulating oil transformers can pressurize and heat the sample oil at the same time, and can achieve a maximum temperature of 200°C by oil bath heating; the maximum voltage can reach 12kV, and the inner diameter of the gas analysis pool pipeline is 51.8mm, and the outer diameter of the electrode is 46.7mm, which can achieve a maximum field strength of 6kV / mm; in addition, 8 circulating pumps are added to ensure that the oil sample is fully circulated, and the flow rate can reach 345.2m / s. The entire electric-thermal combined stress and circulating flow test platform is closer to the actual operation inside the transformer, and the adjustment response is rapid, which can meet the requirements of the electric-thermal coupling field and fluidity test of vegetable insulating oil.

[0029] The specific steps of using the electric-thermal combined stress and circulating flow test platform to test the gas production of insulating oil are as follows:

[0030] (1) The gas analysis cell 1 forms a ground terminal with the high-voltage negative electrode terminal clamp 3 through the aluminum foil 10, and forms an internal and external field strength difference with the negative electrode through the high-voltage line plug 6 (10kV); 50ml of the oil sample to be tested after drying and dehydration is measured and poured into the gas analysis cell 1, and the connection is rinsed with the oil sample to be tested, and the high-voltage electrode 2 is inserted, and the plug of the high-voltage line electrode 5 is connected, and the ground terminal plug is connected, and the gas generation characteristics of the oil sample are observed by pressurizing and heating;

[0031] (2) First, use petroleum ether to clean the gas analysis pool 1, rubber tube 11, inner electrode and syringe respectively; if there is dirt or wax in the gas analysis pool 1 in the previous test, inject petroleum ether into the gas analysis pool 1 and gently scrub it with a hard nylon brush, and then rinse it with petroleum ether;

[0032] (3) Dry the gas analysis cell 1 and the high-voltage electrode 2 in an oven at 80° C. for 30 minutes and preheat them in advance to prevent the gas analysis cell 1 and the high-voltage electrode 2 from being damaged due to inconsistent thermal expansion coefficients;

[0033] (4) Apply a thin layer of vacuum silicone grease at the joint of the gas evolution cell 1 and the rubber tube 11 to ensure the sealing of the test connection. Be careful not to let the vacuum silicone grease enter the gas evolution cell 1;

[0034] (5) Assemble the gas evolution cell 1 with the high-voltage negative electrode terminal clamp 3, place it on the fixed bracket, then rinse the high-voltage electrode interface with the oil sample to be tested, and then insert the high-voltage electrode 2 into the gas evolution cell 1; to prevent potential safety hazards due to excessive micro water in the oil sample, the oil sample must be dried before testing;

[0035] (6) Plug in the 10 kV plug of the high-voltage wire and the 0 kV plug of the high-voltage wire, and the final presentation effect is as Figure 2 shown. Raise the temperature, check the bath temperature, and then turn on the high-voltage power supply. The maximum field strength can reach 5 kV / mm.

[0036] Select domestic refined soybean-based plant insulating oil (NE) as the object and conduct tests under a total of 6 working conditions to explore the influence of field strength on the production of stray gas in natural ester insulating oil and the influence of flow on the production of stray gas in natural ester insulating oil. That is, the tests under 6 working conditions respectively correspond to specific embodiments 1 to 6, as shown in Table 1 for details.

[0037] Table 1 Influence of field strength on the production of stray gas in natural ester insulating oil and influence of flow on the production of stray gas in natural ester insulating oil in specific embodiments 1 to 6

[0038] Specific embodiments 1 2 3 4 5 6 Voltage (kV / mm) 0 kV / mm 2 kV / mm 4 kV / mm 5 kV / mm 0 kV / mm 2 kV / mm Circulation pump None None None None On On Temperature 80℃ 80℃ 80℃ 80℃ 80℃ 80℃

[0039] Since C2H2 gas was not detected under all conditions except 4 kV / mm and 5 kV / mm, the description of this gas will not be involved in the following content. In specific embodiment 3, the C2H2 gas content after testing with a 4 kV / mm oil sample for 8 h is 12.3 μL / L, and in specific embodiment 4, the C2H2 gas content after testing with a 5 kV / mm oil sample for 8 h is 21.7 μL / L; use the David triangle to judge the dissolved gas data after testing the 5 kV / mm oil sample for 8 h. The proportions of C2H2, C2H4, and CH4 are 1.4% / 2% / 94.9% respectively, which is partial discharge (PD) according to the standard.

[0040] Figure 2 Shown is the dissolved gas content and relative proportion in the insulating oil at different field strengths and different times at 80°C. Figure 2 In (a) is the gas production content of NE insulating oil in specific embodiment 1 (0 kV / mm), Figure 2 In (b) is the gas production content of NE insulating oil in specific embodiment 2 (2 kV / mm), Figure 2 In (e) is the gas production content of NE insulating oil in specific embodiment 3 (4 kV / mm), Figure 2 In (f) is the gas production content of NE insulating oil in specific embodiment 4 (5 kV / mm),Figure 2 (c) is the change of the relative proportion of characteristic gases of NE insulating oil in specific embodiment 1 (0 kV / mm) over time. Figure 2 (d) is the change of the relative proportion of characteristic gases of NE insulating oil in specific embodiment 2 (2 kV / mm) over time. Figure 2 (g) is the change of the relative proportion of characteristic gas of NE insulating oil in specific embodiment 3 (4 kV / mm) over time. Figure 2 (h) is the change of the relative proportion of characteristic gases of NE insulating oil in specific embodiment 4 (5kV / mm) over time; since the volume fraction of CO and CO2 produced in the test is relatively large, Figure 2 The gas production trend is clearly expressed in Figure 2 The content of 1 / 2CO and 1 / 6CO2 is shown in the figure. Overall, the characteristic gas content increases significantly with time, among which CO2 gas content is the highest, while C2H4 content is the least obvious, followed by CH4. At the same time, with the increase of field strength, the characteristic gas content increases exponentially. The H2, CO, and CO2 of high field strength oil samples are generally 3 to 5 orders of magnitude higher than the corresponding gases of 0kV / mm oil samples. CO2 can reach a maximum of 33872.79μL / L, and H2 can reach a maximum of 4475.8μL / L.

[0041] Since acetylene is produced under the conditions of Specific Example 3 (4 kV / mm) and Specific Example 4 (5 kV / mm), an electrothermal decomposition test of NE insulating oil with a circulating pump turned on at 0 kV / mm and 2 kV / mm was simulated at 80°C, and the dissolved gas content in the insulating oil after 2, 4, 6, and 8 hours under the two field strengths was obtained, respectively.

[0042] In the gas chromatography oscillation degassing process, it was noted that the degassing volume of the oil sample after circulation was relatively large, averaging 4.2 ml, while under other conditions the average was 3 ml. Figure 3 (a) is the gas production content of NE insulating oil in specific embodiment 5 (0 kV / mm), Figure 3 (b) is the gas production content of NE insulating oil in specific embodiment 6 (2kV / mm), Figure 3 (c) is the change of the relative proportion of characteristic gases of NE insulating oil in specific embodiment 5 (0 kV / mm) over time. Figure 3 (d) shows the change of the relative proportion of characteristic gases of NE insulating oil in specific embodiment 6 (2kV / mm) over time. Since the volume fractions of CO and CO2 produced in the test are relatively large, in order to clearly express the gas production trend in the figure, the figure shows the contents of 1 / 2CO and 1 / 6CO2. Figure 2 ,from Figure 3It can be seen that by increasing the circulating flow of the oil sample, the gas production of characteristic gases is significantly reduced, and almost no C2H4 is produced, and its typical content value is below 4 μL / L. Among them, under the condition of an electric field, the production of non-hydrocarbon gases H2, CO, and CO2 is much greater than that of hydrocarbon gases. From this, it can be seen that the production rate of H2 varies significantly under the conditions of the presence or absence of an electric field, and the gas production rate shows an exponential growth.

[0043] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc., such as the change of a certain material or reaction conditions, made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An outgassing device for measuring the gas generation of insulating oil under an electro-thermal coupling field, characterized in that, It includes a gas evolution cell, a high-voltage electrode, a circulation pump, and an oil bath. The gas evolution cell is connected to the circulation pump. The high-voltage electrode is embedded in the gas evolution cell and connected to a high-voltage power supply. The circulation pump is immersed in the oil bath. An aluminum foil is provided on the outer layer of the gas evolution cell, so that the gas evolution cell is wrapped by the aluminum foil to form an outer electrode, and then grounded through a high-voltage negative electrode terminal block. The circulation pump and a ground wire plug are fixedly combined through a gas evolution cell support plate and immersed in the oil bath. The gas evolution cell is provided with an upper inlet and a lower outlet. Both the upper inlet and the lower outlet of the gas evolution cell are connected to the circulation pump through rubber hoses to form a closed loop for cyclic flow. The high-voltage electrode is connected to the high-voltage power supply through a high-voltage wire plug. The high-voltage electrode is nested with a high-voltage wire electrode through the high-voltage wire plug, and then an electric field loop is formed with the ground wire plug through the high-voltage negative electrode terminal block of the gas evolution cell.

2. The gas evolution device for measuring the gas production of insulating oil under the electro-thermal coupling field according to claim 1, wherein A bracket is provided in the oil bath for fixing the gas evolution cell and the high-voltage wire electrode.

3. The gas evolution device for measuring the gas production of insulating oil under the electro-thermal coupling field according to claim 1, wherein, The oil bath is a glass oil bathtub, which is internally provided with a constant temperature controller and a stirring device.

4. The gas evolution device for measuring gas production of insulating oil under the electro-thermal coupling field according to claim 1, characterized in that, A metal platinum resistance is provided in the oil bath as a temperature measuring element.

5. The gas evolution device for measuring the gas generation of insulating oil under the electro-thermal coupling field according to claim 2, wherein The capacity of the gas evolution cell is 50 mL; the inner diameter of the rubber hose is 4 mm, the flow rate of the circulation pump is 260 mL per minute, and the maximum flow velocity is 345.2 m / s.

6. The gas evolution device for measuring the gas generation of insulating oil under the electro-thermal coupling field according to claim 5, characterized in that, An analysis gas generation device for measuring insulating oil under an electrothermal coupling field is used to build an electrothermal combined stress and cyclic flow test platform. The high-voltage electrode in the electrothermal combined stress and cyclic flow test platform is made of stainless steel and its surface is polished. The outer diameter of the high-voltage electrode is 46.7 mm, and the inner diameter of the pipeline of the gas evolution cell is 51.8 mm. The high-voltage electrode is inserted into the gas evolution cell, so that the oil sample is distributed within a 2-mm gap of the electrode. The maximum voltage of the voltage generator is 12 kV. According to the electric field strength = voltage / distance, the maximum electric field strength of 6 kV / mm is achieved.

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