Method and system for evaluating aging resistance performance of generator stator coil in high-altitude environment

Abstract

The present application belongs to the technical field of generator stator coil material, and particularly relates to a method and system for evaluating the aging resistance of a generator stator coil in a high-altitude environment. Based on the research on the service characteristics and evolution law of the generator stator coil in a high-altitude environment, the present application proposes, for the first time, to evaluate the aging resistance of the generator stator coil by the following indexes: the breakdown voltage of the stator coil, the concentration of volatile organic compounds detected under the condition of thermal oxidative aging, the thermal conductivity, the specific surface area of solid substances, the porosity and the liquid adsorption performance. The evaluation method of the present application has the advantages of accuracy and rapidness, and has a good application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of generator stator coil materials, and particularly relates to a method and system for evaluating the aging resistance of a generator stator coil in a high-altitude environment. BACKGROUND

[0002] Large high-voltage generator stator coils have high voltage resistance, low dielectric loss, good anti-corona performance, high strength, high rigidity, vibration resistance, and high thermal conductivity. They are installed in large high-voltage generator stators and play a key role in generating induced electromotive force and transmitting electric energy during power generation. The generator stator coil is a multi-layer composite structure. From the inside out, there is first a semiconductor layer on the surface of the conductor, which improves the electric field distribution on the surface of the conductor, reduces the local electric field strength, and prevents corona initiation. Then there is a main insulation layer, usually made of high-performance insulation materials such as mica tape, which is wound and cured in multiple layers, has good electrical insulation performance, mechanical properties, and heat resistance, and can withstand high voltage during generator operation. Then there is an insulation shielding layer, which is mainly used to uniform the electric field on the surface of the main insulation and avoid electric field concentration, further improving the reliability of the insulation.

[0003] In recent years, generator stator coils have been increasingly applied in high-altitude areas. When generator stator coils work in high-altitude areas, they face severe working conditions with the following characteristics:

[0004] Difficult heat dissipation due to thin air: In high-altitude areas, air density is low, and the thermal conductivity and specific heat capacity of the gas are small, which greatly weakens the effect of heat dissipation through air convection of the stator coil. This can cause the heat generated by the stator coil during operation to be difficult to dissipate, easily leading to high temperature, accelerating the aging of the insulation material, reducing its insulation performance and mechanical strength, and affecting the normal operation and service life of the generator;

[0005] Increased insulation performance requirements: As the altitude increases, air pressure decreases, and the insulation strength of the gas decreases. When the stator coil operates in high-altitude areas, it is more likely to cause corona discharge and partial discharge under the same voltage, which puts higher requirements on the insulation performance of the insulation material. At the same time, the thin air also reduces the flashover voltage on the surface of the insulation material, increasing the risk of insulation breakdown;

[0006] Changes in electrical performance: In high-altitude areas, the air is thin, and the electric field distribution changes, causing changes in the electrical parameters of the stator coil, such as capacitance and inductance. This may affect the output characteristics and stability of the generator, making the operation control of the generator more complex;

[0007] Mechanical stress increases: the temperature in high altitude areas is low, and the temperature difference between day and night is large. The stator coil and its fixed parts will produce a large mechanical stress due to thermal expansion and contraction. In addition, the air is thin, resulting in a decrease in wind resistance, and the efficiency of the generator cooling fan may change, causing problems such as vibration, which puts higher requirements on the mechanical fixing structure of the stator coil to prevent the coil from being worn or loosened due to vibration.

[0008] In summary, it is of great significance to judge the pros and cons of the aging resistance performance of the generator stator coil in high altitude areas. However, the systematic study of the aging of the generator stator coil in high altitude areas is still insufficient. Therefore, there is still a lack of a standard and accurate evaluation method for the aging resistance performance of the generator stator coil. In practical applications, the aging behavior of the generator stator coil insulation during service in high altitude environments often occurs slowly, lasting for several years or even decades. Therefore, the existing evaluation method for aging resistance performance often adopts accelerated testing, even so, the cycle of accelerated testing is as long as several months or even longer, and the accuracy is poor, which seriously affects the development of high-performance generator stator coils. SUMMARY

[0009] To solve the above problems, the present application analyzes the aging mechanism of the generator stator coil during service in high altitude areas, and finds that the factors affecting the aging resistance performance of the generator stator coil in high altitude areas not only include its own thermal conductivity and dielectric properties, but also are directly related to the internal microstructure of the stator coil (such as the specific surface area of the internal structure, the internal defect porosity, etc.). At the same time, the concentration of specific gases released during thermal oxidative aging is also an important parameter reflecting the aging resistance performance of the generator stator coil in high altitude areas.

[0010] A method for evaluating the aging resistance performance of a generator stator coil in high altitude environments, which evaluates the aging resistance performance of the generator stator coil through the following indexes: testing the breakdown voltage of the stator coil, detecting the concentration of volatile organic compounds under thermal oxidative aging conditions, the thermal conductivity, the specific surface area of solid substances, the porosity, and the liquid adsorption performance.

[0011] Preferably, the aging resistance performance of the generator stator coil is evaluated by an evaluation parameter, and the calculation formula of the evaluation parameter is:

[0012] ,

[0013] wherein, R aging the evaluation parameter, the value of which is positively correlated with the aging resistance performance of the generator stator coil; V the breakdown voltage of the stator coil; C gasto test the concentration of volatile organic compounds detected by the stator coil under the condition of thermal oxygen aging; K to test the thermal conductivity of the stator coil; A to test the specific surface area of solid substances of the stator coil; φ to test the porosity of the stator coil; ω absorb to test the liquid adsorption performance of the stator coil, expressed as the percentage of the adsorbed liquid to the weight of the stator coil itself; t absorb to test the liquid adsorption performance of the stator coil, expressed as the time required for adsorption to reach saturation; k 1 、 k 2 、 k 3 is a constant, and its value range is: k 1 = 47.9 ~ 52.4, k 2 = 155.1 ~ 165.8, k 3 = 199 ~ 209.22.

[0014] Preferably, k 1 = 49.8, k 2 = 161.7, k 3 = 208.15.

[0015] Preferably, the concentration of volatile organic compounds detected by the test stator coil under the condition of thermal oxygen aging is detected by the following method:

[0016] The test stator coil is subjected to thermal oxygen aging in a vacuum oven, and the thermal oxygen aging conditions are: pressure 50 ~ 70 kPa, thermal oxygen aging temperature 140 ~ 200℃, and thermal oxygen aging time 50 ~ 200 hours; the gas in the vacuum oven is extracted, and the volatile organic compounds are tested by gas chromatography, and the test temperature is 140 ~ 200℃.

[0017] Preferably, the type of volatile organic compounds is one or a combination of the following substances: N -methoxy methylamine, formaldehyde, acetaldehyde, benzene, carbon monoxide.

[0018] Preferably, the liquid absorption performance of the test stator coil is tested according to the following method: the test stator coil is immersed in the liquid at 25 DEG C and 1 atm, and repeatedly taken out, surface dried, weighed, and immersed until the weight no longer changes with the immersion time, which is considered to be saturated absorption; the percentage of the absorbed liquid to the weight of the stator coil itself is calculated w absorb , and the time required for saturated absorption t absorb .

[0019] Preferably, the liquid is selected from one of the following reagents: ethylene glycol methyl ether, propylene glycol methyl ether, diethylene glycol methyl ether, N-methyl pyrrolidone, dimethyl sulfoxide, white oil, and silicone oil.

[0020] Preferably, the thermal conductivity is tested by the hot-wire method, the heat source method, the transient plane heat source method, the temperature wave analysis method, the laser flash method, the guarded hot plate method, the guarded hot flow meter method, or the heat flow meter method (for specific implementation methods, refer to the national standard GB / T 42919.1-2023 "Determination of thermal conductivity and thermal diffusivity of plastics - Part 1: General principles").

[0021] Preferably, the specific surface area of the solid substance is tested by the gas adsorption BET method (for specific implementation methods, refer to the national standard GB / T 19587-2017 "Determination of specific surface area of solid substances by gas adsorption BET method").

[0022] And / or, the breakdown voltage is the voltage at which the sample breaks down in a continuous voltage rise test, or the breakdown voltage is the highest voltage that the sample can withstand in a step-by-step voltage rise test (for specific implementation methods, refer to the national standard GB / T 1408.1-2016 "Insulating materials - Determination of electrical strength in liquid - Test methods - Part 1: Test at power frequency").

[0023] The application also provides a high-altitude environment generator stator coil aging resistance performance evaluation system, comprising:

[0024] The parameter input module is configured to input test generator stator coil related indicators, including: the breakdown voltage of the test stator coil, the concentration of volatile organic compounds detected under thermal oxidative aging conditions, the thermal conductivity, the specific surface area of the solid substance, the porosity, and the liquid absorption performance.

[0025] The operation module is configured to evaluate the aging resistance performance of the generator stator coil according to the high-altitude environment generator stator coil aging resistance performance evaluation method.

[0026] In the application, the high-altitude environment refers to an environment with an altitude of 1000-8848 meters.

[0027] Based on the research on the service characteristics and evolution law of the generator stator coil in the high altitude environment, the application proposes that the anti-aging performance of the generator stator coil in the high altitude area is not only related to the heat conduction performance and dielectric performance, but also directly related to the internal microstructure of the stator coil (such as the specific surface area of the internal structure, the internal defect porosity, etc.). Through the design of a special experimental method, the key characteristic parameters of the stator coil are obtained, and the evaluation parameter reflecting the anti-aging performance of the generator stator coil in the high altitude area is calculated by designing a formula, so as to realize the accurate and rapid evaluation of the anti-aging performance of the generator stator coil in the high altitude area.

[0028] Obviously, according to the above content of the application, according to the ordinary technical knowledge and conventional means in the art, other various forms of modification, replacement or change can be made without departing from the above basic technical idea of the application. DETAILED DESCRIPTION

[0029] The above content of the application will be further explained in detail through the specific embodiments in the form of examples. However, it should not be understood that the above subject matter of the application is limited to the following examples. Any technology realized based on the above content of the application belongs to the scope of the application.

[0030] In the following examples and experimental examples, the reagents and raw materials not specifically explained are commercially available.

[0031] It should be particularly noted that the algorithms of the data acquisition, transmission, storage and processing steps not specifically explained in the examples, and the hardware structure, circuit connection and the like not specifically explained can be realized through the existing technology.

[0032] Example 1: Evaluation method and system for anti-aging performance of generator stator coil in high altitude environment

[0033] The system for evaluating the anti-aging performance of the generator stator coil in the high altitude environment provided in this embodiment comprises:

[0034] The parameter input module is configured to input the relevant indexes of the test generator stator coil, including: the breakdown voltage of the test stator coil, the concentration of volatile organic compounds detected under thermal oxidative aging conditions, the thermal conductivity, the specific surface area of solid substances, the porosity, and the liquid adsorption performance.

[0035] The operation module is configured to evaluate the anti-aging performance of the generator stator coil.

[0036] The method for evaluation through the above system is:

[0037] (1) The stator coil is subjected to a thermal oxidation aging experiment in a vacuum oven, and the experimental conditions are as follows: the pressure in the vacuum oven is 50-70 kPa, the thermal oxidation aging temperature is 140-200℃, and the thermal oxidation aging time is 50-200 hours, then the gas in the vacuum oven is extracted, and the gas chromatography test is carried out according to HJ 759-2023 "Determination of 65 kinds of volatile organic compounds in ambient air Tank sampling / Gas chromatography-mass spectrometry", the test temperature is 140-200℃, and the concentration value of the detected substance G is recorded as C gas , unit ppm;

[0038] (2) The substance G is a combination of one or more of the following substances: N -methoxy methylamine, formaldehyde, acetaldehyde, benzene, carbon monoxide; when the substance G is a combination of multiple substances, the concentration value of the substance G represents the total concentration of each substance;

[0039] (3) The thermal conductivity of the stator coil is tested, and its thermal conductivity coefficient K is obtained, unit W / (m・℃), the test method is hot wire method, heat source method, transient plane heat source method, temperature wave analysis method, laser flash method, protective hot plate method, protective heat flow meter method or heat flow meter method, preferably transient plane heat source (hot disc) method or laser flash method, according to national standard GB / T 42919.1-2023 "Determination of thermal conductivity and thermal diffusivity of plastics Part 1: General rules";

[0040] (4) The specific surface area of solid substance of the stator coil is tested A , unit m 2 / g, the test method is gas adsorption BET method, according to national standard GB / T 19587-2017 "Determination of specific surface area of solid substance by gas adsorption BET method";

[0041] (5) According to the method proposed in the literature

A. Djerbi Tegguer, Determining the water absorption of recycled aggregates utilizing hydrostatic weighing approach, Construction and Building Materials, 27, 1, 2012, 112-116.

[0042] (6) The above liquid X It is one of the following liquids: ethylene glycol methyl ether, propylene glycol methyl ether, diethylene glycol methyl ether, N-methylpyrrolidone, dimethyl sulfoxide, white oil, silicone oil;

[0043] (7) The breakdown voltage is the voltage at which the sample breaks down during a continuous voltage ramp test; or the highest voltage the sample withstands during a step-by-step voltage ramp test. The breakdown voltage of the stator coil is tested according to the national standard GB / T 1408.1-2016 "Electrical Strength Test Methods for Insulating Materials Part 1: Tests at Power Frequency". V Unit: kV;

[0044] (8) Use X-ray computed tomography (CT) to test the porosity of the stator coil. φ The unit is %, and the test method is based on the reference [Iryna Tretiak, Robert A. Smith, A parametric study of segmentation thresholds for X-ray CT porosity characterisation in composite materials, Composites Part A: Applied Science and Manufacturing, 123, 2019, 10-24.].

[0045] (9) Calculate the evaluation parameters for measuring the aging resistance of stator coils in high-altitude areas using the following formula. R aging ， R aging The larger the value, the better the aging resistance of the generator stator coil in high-altitude areas. The calculation formula is as follows:

[0046] ,

[0047] in, R aging The evaluation parameter is positively correlated with the aging resistance of the generator stator coil. VTo test the breakdown voltage of the stator coils; C gas To test the concentration of volatile organic compounds (i.e., substances) detected in the stator coil under thermo-oxidative aging conditions. G (concentration value); K To test the thermal conductivity of the stator coils; A To test the specific surface area of ​​the solid material in the stator coil; φ To test the porosity of the stator coils; ω absorb The test results for the liquid adsorption performance of the stator coil are expressed as the percentage of the weight of the adsorbed liquid relative to the stator coil itself. t absorb The test results for the liquid adsorption performance of the stator coil indicate the time required for adsorption to reach saturation. k 1 , k 2 , k 3 It is a constant, and its range of values ​​is: k 1 =47.9~52.4, k 2 =155.1~165.8, k 3 =199~209.22. In this embodiment, k 1 , k 2 , k 3 Preferred k 1 =49.8, k 2 =161.7, k 3 =208.15. In other embodiments, other values ​​within the range may also be selected, for example: k 1 =47.9, k 2 =165.8, k 3 =199, or k 1 =52.4, k 2 =155.1, k 3 =209.22.

[0048] The technical solution of the present invention will be further explained below based on the test results of the reagent samples:

[0049] Experimental Example 1

[0050] For two samples, generator stator coils A and B, the method proposed in Example 1 was used to determine the superiority of their aging resistance performance in high-altitude applications:

[0051] (1) Stator coils A and B were subjected to thermo-oxidative aging experiments in a vacuum oven. The experimental conditions were: pressure in the vacuum oven was 52 kPa, thermo-oxidative aging temperature was 143℃, and thermo-oxidative aging time was 198 hours. Then, the gas in the vacuum oven was extracted and gas chromatography was performed according to HJ 759-2023 "Determination of 65 Volatile Organic Compounds in Ambient Air - Canister Sampling / Gas Chromatography-Mass Spectrometry". The test temperature was 143℃. The gas extracted from the vacuum oven of stator coils A and B was detected to contain... N The concentration values ​​of -methoxymethylamine were respectively C gasA =1597 ppm, C gasB =1770 ppm;

[0052] (2) The thermal conductivity of the stator coils was tested, and the thermal conductivity of stator coils A and B were obtained as follows: K A =0.37 W / (m・℃), K B =0.59 W / (m・℃), the test method is transient plane heat source (heat plate) method, according to national standard GB / T 42919.1-2023 "Determination of thermal conductivity and thermal diffusivity of plastics Part 1: General rules";

[0053] (3) Test the specific surface area of ​​the solid material of stator coils A and B. A A = 6.06m 2 / g, A B = 2.32m 2 / g, the test method is gas adsorption BET method, and it is carried out according to the national standard GB / T 19587-2017 "Determination of specific surface area of ​​solid substances by gas adsorption BET method";

[0054] (4) According to the method proposed in the literature [A. Djerbi Tegguer, Determining the water absorption of recycled aggregates utilizing hydrostatic weighing approach, Construction and Building Materials, 27, 1, 2012, 112-116.], the liquid adsorption performance of stator coils A and B was tested. First, they were immersed in ethylene glycol methyl ether at 25°C and normal atmospheric pressure. Then, they were taken out, wiped dry, and weighed at regular intervals until the weight no longer changed with the immersion time, which was considered as adsorption saturation. The percentage of the adsorbed liquid to the weight of stator coils A and B were obtained as follows: w absorbA =62 wt%, w absorbB =58 wt%, and the time required for adsorption to reach saturation are respectively t absorbA =2 h, t absorbB =15 h;

[0055] (5) The breakdown voltage is the highest voltage that the sample can withstand during the step-up voltage test. According to the national standard GB / T1408.1-2016 "Electrical Strength Test Methods for Insulating Materials - Part 1: Tests at Power Frequency", the breakdown voltages of stator coils A and B are tested. V A =100 kV, V B =25 kV;

[0056] (6) The porosities of stator coils A and B were measured using X-ray computed tomography (CT) and were respectively... φ A = 3.0%, φ B = 3.5%, the test method is based on the reference [Iryna Tretiak, Robert A. Smith, A parametric study of segmentation thresholds for X-ray CT porosity characterisation in composite materials, Composites Part A: Applied Science and Manufacturing, 123, 2019, 10-24.].

[0057] Use the following formula:

[0058] ,

[0059] The evaluation parameters for measuring the aging resistance of stator coils A and B in high-altitude areas are calculated as follows: R agingA =5.813, R agingB =8.273. The results show that... R agingB Greater than R agingA This indicates that stator coil B has better aging resistance than stator coil A in high-altitude areas. To verify the accuracy of the above conclusion, an accelerated aging simulation experiment was conducted on stator coils A and B under the combined effects of high temperature and corona discharge in a high-altitude environment for 24 months. The results showed that stator coil A aged faster and failed earlier, indicating that stator coil B has better aging resistance in high-altitude environments. This is consistent with the calculation results of this invention, demonstrating that the evaluation method proposed in this invention is accurate and effective.

[0060] Experiment Example 2

[0061] For generator stator coils C and D, the method proposed in Example 1 is used to determine the relative performance of C and D in terms of aging resistance for applications in high-altitude areas:

[0062] (1) Stator coils C and D were subjected to thermo-oxidative aging experiments in a vacuum oven. The experimental conditions were: pressure in the vacuum oven was 70 kPa, thermo-oxidative aging temperature was 185℃, and thermo-oxidative aging time was 93 hours. Then, the gas in the vacuum oven was extracted and gas chromatography was performed according to HJ 759-2023 "Determination of 65 Volatile Organic Compounds in Ambient Air - Canister Sampling / Gas Chromatography-Mass Spectrometry". The test temperature was 185℃. The formaldehyde concentration values ​​in the vacuum oven extracted from stator coils C and D were respectively... C gasC =771 ppm, C gasD =492 ppm;

[0063] (2) The thermal conductivity of the stator coils was tested, and the thermal conductivity of stator coils C and D were obtained as follows: K C =0.19 W / (m・℃), K D=0.35 W / (m・℃), the test method is laser flash method, according to national standard GB / T 42919.1-2023 "Determination of thermal conductivity and thermal diffusivity of plastics - Part 1: General rules";

[0064] (3) Test the solid surface area of ​​stator coils C and D. A C = 3.30 m 2 / g, A D = 4.08 m 2 / g, the test method is gas adsorption BET method, and it is carried out according to the national standard GB / T 19587-2017 "Determination of specific surface area of ​​solid substances by gas adsorption BET method";

[0065] (4) According to the method proposed in the literature [A. Djerbi Tegguer, Determining the water absorption of recycled aggregates utilizing hydrostatic weighing approach, Construction and Building Materials, 27, 1, 2012, 112-116.], the liquid adsorption performance of stator coils C and D was tested. First, they were immersed in dimethyl sulfoxide at 25°C and normal atmospheric pressure. Then, they were taken out, dried, and weighed at intervals until the weight no longer changed with the immersion time, which was considered as adsorption saturation. The percentage of the adsorbed liquid to the weight of stator coils C and D were obtained as follows: w absorbC =45 wt%, w absorbD =62 wt%, and the time required for adsorption to reach saturation are respectively t absorbC =4 h, t absorbD =18 h;

[0066] (5) The breakdown voltage is the highest voltage that the sample can withstand during the step-up voltage test. According to the national standard GB / T1408.1-2016 "Electrical Strength Test Methods for Insulating Materials - Part 1: Tests at Power Frequency", the breakdown voltages of stator coils C and D are tested. V C =19 kV, V D =32 kV;

[0067] (6) The porosities of stator coils C and D were tested using X-ray computed tomography (CT) and were respectively... φ C = 1.9%, φ D = 1.5%, the test method is based on the reference [Iryna Tretiak, Robert A. Smith, A parametric study of segmentation thresholds for X-ray CT porosity characterisation in composite materials, Composites Part A: Applied Science and Manufacturing, 123, 2019, 10-24.].

[0068] Use the following formula:

[0069] ,

[0070] The evaluation parameters for measuring the aging resistance of stator coils C and D in high-altitude areas are calculated as follows: R agingC =5.262, R agingD =7.125. The results show that... R agingD Greater than R agingC This indicates that stator coil D has better aging resistance than stator coil C in high-altitude areas. To verify the accuracy of the above conclusion, an accelerated aging simulation experiment was conducted on stator coils C and D under the combined effects of high temperature and corona discharge in a high-altitude environment for 24 months. The results show that stator coil C ages faster and fails earlier, indicating that stator coil D has better aging resistance in high-altitude environments. This is consistent with the calculation results of this invention, demonstrating that the evaluation method proposed in this invention is accurate and effective.

[0071] Experimental Example 3

[0072] For generator stator coils E and F, the method proposed in Example 1 is used to determine the relative performance of E and F in terms of aging resistance for applications in high-altitude areas:

[0073] (1) Stator coils E and F were subjected to thermo-oxidative aging experiments in a vacuum oven. The experimental conditions were: pressure in the vacuum oven was 53 kPa, thermo-oxidative aging temperature was 176℃, and thermo-oxidative aging time was 50 hours. Then, the gas in the vacuum oven was extracted and gas chromatography was performed according to HJ 759-2023 "Determination of 65 Volatile Organic Compounds in Ambient Air - Canister Sampling / Gas Chromatography-Mass Spectrometry". The test temperature was 176℃. The concentration values ​​of acetaldehyde in the vacuum oven extracted gas of stator coils E and F were respectively... C gasE =838 ppm, C gasF =1586 ppm;

[0074] (2) The thermal conductivity of the stator coils was tested, and the thermal conductivity of stator coils E and F were obtained as follows: K E =0.53 W / (m・℃), K F =0.29 W / (m・℃), the test method is laser flash method, according to national standard GB / T 42919.1-2023 "Determination of thermal conductivity and thermal diffusivity of plastics - Part 1: General rules";

[0075] (3) Test the solid surface area of ​​stator coils E and F. A E = 3.12 m 2 / g, A F = 5.83 m 2 / g, the test method is gas adsorption BET method, and it is carried out according to the national standard GB / T 19587-2017 "Determination of specific surface area of ​​solid substances by gas adsorption BET method";

[0076] (4) According to the method proposed in the literature [A. Djerbi Tegguer, Determining the water absorption of recycled aggregates utilizing hydrostatic weighing approach, Construction and Building Materials, 27, 1, 2012, 112-116.], the liquid adsorption performance of stator coils E and F was tested. First, they were immersed in white oil at 25℃ and normal atmospheric pressure. Then, they were taken out, wiped dry and weighed at regular intervals until the weight no longer changed with the immersion time, which was considered as adsorption saturation. The percentage of the adsorbed liquid to the weight of stator coils E and F were obtained as follows:w absorbE =50wt%, w absorbF =41wt%, and the time required for adsorption to reach saturation are respectively... t absorbE =2 h, t absorbF =3.2 h;

[0077] (5) The breakdown voltage is the highest voltage that the sample can withstand during the step-up voltage test. According to the national standard GB / T1408.1-2016 "Electrical Strength Test Methods for Insulating Materials - Part 1: Tests at Power Frequency", the breakdown voltages of stator coils E and F are tested. V E =66 kV, V F =31 kV;

[0078] (6) The porosities of stator coils E and F were tested using X-ray computed tomography (CT) and were respectively... φ E = 2%, φ F = 3.2%, the testing method is based on the reference [Iryna Tretiak, Robert A. Smith, A parametric study of segmentation thresholds for X-ray CT porosity characterisation in composite materials, Composites Part A: Applied Science and Manufacturing, 123, 2019, 10-24.].

[0079] Use the following formula:

[0080] ,

[0081] The evaluation parameters for measuring the aging resistance of stator coils E and F in high-altitude areas are calculated as follows: R agingE =15.254, R agingF =0.335. The results show that... R agingE Greater than R agingFThis indicates that stator coil E has better aging resistance than stator coil F in high-altitude areas. To verify the accuracy of the above conclusion, an accelerated aging simulation experiment was conducted on stator coils E and F under the combined effects of high temperature and corona discharge in a high-altitude environment for 24 months. The results show that stator coil F ages faster and fails earlier, indicating that stator coil E has better aging resistance in high-altitude environments. This is consistent with the calculation results of this invention, demonstrating that the evaluation method proposed in this invention is accurate and effective.

[0082] Experiment Example 4

[0083] For generator stator coils G and H, the method proposed in Example 1 is used to determine the quality of their aging resistance in high-altitude applications:

[0084] (1) Stator coils G and H were subjected to thermo-oxidative aging experiments in a vacuum oven. The experimental conditions were: pressure in the vacuum oven was 63 kPa, thermo-oxidative aging temperature was 197℃, and thermo-oxidative aging time was 159 hours. Then, the gas in the vacuum oven was extracted and gas chromatography was performed according to HJ 759-2023 "Determination of 65 Volatile Organic Compounds in Ambient Air by Canister Sampling / Gas Chromatography-Mass Spectrometry". The test temperature was 197℃. The concentration values ​​of carbon monoxide in the gas extracted from the vacuum oven of stator coils G and H were respectively... C gasG =1642 ppm, C gasH =749 ppm;

[0085] (2) The thermal conductivity of the stator coils was tested, and the thermal conductivity of stator coils G and H were obtained as follows: K G =0.60 W / (m・℃), K H =0.41 W / (m・℃), the test method is transient plane heat source (heat plate) method, according to national standard GB / T 42919.1-2023 "Determination of thermal conductivity and thermal diffusivity of plastics Part 1: General rules";

[0086] (3) Test the solid surface area of ​​stator coils G and H. A G = 4.64m 2 / g, A H = 2.51m 2 / g, the test method is gas adsorption BET method, and it is carried out according to the national standard GB / T 19587-2017 "Determination of specific surface area of ​​solid substances by gas adsorption BET method";

[0087] (4) According to the method proposed in the literature [A. Djerbi Tegguer, Determining the water absorption of recycled aggregates utilizing hydrostatic weighing approach, Construction and Building Materials, 27, 1, 2012, 112-116.], the liquid adsorption performance of stator coils G and H was tested. First, they were immersed in water at 25°C and normal atmospheric pressure. N The liquid was placed in methylpyrrolidone, and then removed, dried, and weighed at intervals until the weight no longer changed with soaking time, at which point adsorption was considered saturated. The percentages of the adsorbed liquid relative to the weight of the stator coils G and H were obtained as follows: w absorbG =33 wt% w absorbH =66 wt%, and the time required for adsorption to reach saturation are respectively t absorbG =16 h, t absorbH =2 h;

[0088] (5) The breakdown voltage is the highest voltage that the sample can withstand during the step-up voltage test. According to the national standard GB / T1408.1-2016 "Electrical Strength Test Methods for Insulating Materials - Part 1: Tests at Power Frequency", the breakdown voltages of stator coils G and H are tested. V G =79 kV, V H =19 kV;

[0089] (6) The porosities of stator coils G and H were tested using X-ray computed tomography (CT) and were respectively... φ G = 3.9%, φ H =0.6%, the test method is based on the reference [Iryna Tretiak, Robert A. Smith, A parametric study of segmentation thresholds for X-ray CT porosity characterisation in composite materials, Composites Part A: Applied Science and Manufacturing, 123, 2019, 10-24.].

[0090] Use the following formula:

[0091] ,

[0092] The evaluation parameters for measuring the aging resistance of stator coils G and H in high-altitude areas are calculated as follows: R agingG =5.220, R agingH =44.651. The results show that... R agingH Greater than R agingG This indicates that stator coil H has better aging resistance than stator coil G in high-altitude areas. To verify the accuracy of the above conclusion, an accelerated aging simulation experiment was conducted on stator coils G and H under the combined effects of high temperature and corona discharge in a high-altitude environment for 24 months. The results show that stator coil G ages faster and fails earlier, indicating that stator coil H has better aging resistance in high-altitude environments. This is consistent with the calculation results of this invention, demonstrating that the evaluation method proposed in this invention is accurate and effective.

[0093] Experimental Example 5

[0094] For generator stator coils I and J, the method proposed in Example 1 is used to determine the relative performance of I and J in terms of aging resistance for applications in high-altitude areas:

[0095] (1) Stator coils I and J were subjected to thermo-oxidative aging experiments in a vacuum oven. The experimental conditions were: pressure in the vacuum oven was 50 kPa, thermo-oxidative aging temperature was 155℃, and thermo-oxidative aging time was 129 hours. Then, the gas in the vacuum oven was extracted and gas chromatography was performed according to HJ 759-2023 "Determination of 65 Volatile Organic Compounds in Ambient Air by Canister Sampling / Gas Chromatography-Mass Spectrometry". The test temperature was 155℃. The concentration values ​​of benzene in the vacuum oven extracted from stator coils I and J were respectively... C gasI=405 ppm, C gasJ =1257 ppm;

[0096] (2) The thermal conductivity of the stator coils was tested, and the thermal conductivity of stator coils I and J were obtained as follows: K I =0.19 W / (m・℃), K J =0.23 W / (m・℃), the test method is transient plane heat source (heat plate) method, according to national standard GB / T 42919.1-2023 "Determination of thermal conductivity and thermal diffusivity of plastics Part 1: General rules";

[0097] (3) Test the solid surface area of ​​stator coils I and J. A I = 2.99 m 2 / g, A J = 2.08 m 2 / g, the test method is gas adsorption BET method, and it is carried out according to the national standard GB / T 19587-2017 "Determination of specific surface area of ​​solid substances by gas adsorption BET method";

[0098] (4) According to the method proposed in the literature [A. Djerbi Tegguer, Determining the water absorption of recycled aggregates utilizing hydrostatic weighing approach, Construction and Building Materials, 27, 1, 2012, 112-116.], the liquid adsorption performance of stator coils I and J was tested. First, they were immersed in diethylene glycol methyl ether at 25°C and normal atmospheric pressure. Then, they were taken out, wiped dry, and weighed at intervals until the weight no longer changed with the immersion time, which was considered as adsorption saturation. The percentage of the adsorbed liquid to the weight of stator coils I and J were obtained as follows: w absorbI =53wt%, w absorbJ =64wt%, and the time required for adsorption to reach saturation are respectively... t absorbI =2 h, t absorbJ =13 h;

[0099] (5) The breakdown voltage is the highest voltage that the sample can withstand during the step-up voltage test. According to the national standard GB / T1408.1-2016 "Electrical Strength Test Methods for Insulating Materials - Part 1: Tests at Power Frequency", the breakdown voltages of stator coils I and J are tested. V I =53 kV, V J =99 kV;

[0100] (6) The porosities of stator coils I and J were tested using X-ray computed tomography (CT) and were respectively φ I = 2.9%, φ φ J = 1.9%, the test method is based on the reference [Iryna Tretiak, Robert A. Smith, A parametric study of segmentation thresholds for X-ray CT porosity characterisation in composite materials, Composites Part A: Applied Science and Manufacturing, 123, 2019, 10-24.].

[0101] Use the following formula:

[0102] ,

[0103] The evaluation parameters for measuring the aging resistance of stator coils I and J in high-altitude areas are calculated as follows: R agingI =9.550, R agingJ =9.336. The results show that, R agingI Greater than R agingJ This indicates that stator coil I has better aging resistance than stator coil J in high-altitude areas. To verify the accuracy of the above conclusion, an accelerated aging simulation experiment under the combined effects of high temperature and corona discharge in a high-altitude environment was conducted on stator coils I and J for 24 months. The results show that stator coil J ages faster and fails earlier, indicating that stator coil I has better aging resistance in high-altitude environments. This is consistent with the calculation results of this invention, demonstrating that the evaluation method proposed in this invention is accurate and effective.

[0104] As can be seen from the above embodiments and experimental examples, the evaluation of the aging resistance of generator stator coils under high-altitude environments using the method and system of the present invention can yield accurate and reliable results. Furthermore, the method of the present invention does not require prolonged accelerated aging simulation experiments, offering advantages in efficiency and simplicity compared to existing experimental testing methods. Therefore, the present invention has excellent application prospects.

Claims

1. A method for evaluating the aging resistance performance of generator stator coils in high-altitude environments, characterized in that, The aging resistance performance of generator stator coils is jointly evaluated by the following indicators: breakdown voltage of stator coils, concentration of volatile organic compounds detected under thermo-oxidative aging conditions, thermal conductivity, specific surface area of ​​solid material, porosity, and liquid adsorption performance. The aging resistance of the generator stator coil is evaluated using assessment parameters, which are calculated using the following formulas: ， in, R aging The evaluation parameter is positively correlated with the aging resistance of the generator stator coil. V To test the breakdown voltage of the stator coils; C gas To test the concentration of volatile organic compounds detected in the stator coil under thermo-oxidative aging conditions; K To test the thermal conductivity of the stator coils; A To test the specific surface area of ​​the solid material in the stator coil; φ To test the porosity of the stator coils; ω absorb The test results for the liquid adsorption performance of the stator coil are expressed as the percentage of the weight of the adsorbed liquid relative to the stator coil itself. t absorb The test results for the liquid adsorption performance of the stator coil indicate the time required for adsorption to reach saturation. k 1 , k 2 , k 3 It is a constant, and its range of values ​​is: k 1 =47.9~52.4, k 2 =155.1~165.8, k 3 =199~209.22; in: The concentration of volatile organic compounds detected in the test stator coil under thermo-oxidative aging conditions was obtained according to the following method: The stator coils were subjected to thermo-oxidative aging in a vacuum oven under the following conditions: pressure 50-70 kPa, temperature 140-200℃, and time 50-200 hours. Gas was extracted from the vacuum oven, and volatile organic compounds were analyzed by gas chromatography at a temperature of 140-200℃. The volatile organic compounds were one or more of the following substances: N -Methoxymethylamine, formaldehyde, acetaldehyde, benzene, carbon monoxide; the concentration of the volatile organic compounds is in ppm; The liquid adsorption performance of the stator coil was tested as follows: At 25°C and one atmosphere, the stator coil was immersed in liquid. It was repeatedly removed, dried, weighed, and immersed again until the weight no longer changed with immersion time, at which point adsorption was considered saturated. The percentage of adsorbed liquid relative to the weight of the stator coil was calculated. w absorb And the time required for adsorption to reach saturation. t absorb The liquid is selected from one of the following reagents: ethylene glycol methyl ether, diethylene glycol methyl ether, N-methylpyrrolidone, dimethyl sulfoxide, and white oil; w absorb The unit is wt%, the t absorb The unit is h; The thermal conductivity was tested using the transient planar heat source method or the laser flash method; the unit of the thermal conductivity is W / (m·℃); The specific surface area of ​​the solid material was tested using the gas adsorption BET method; the unit of the specific surface area of ​​the solid material is m². 2 / g; The breakdown voltage is the voltage at which the sample breaks down during a continuous voltage ramp test; or the breakdown voltage is the highest voltage the sample withstands during a step-by-step voltage ramp test; the unit of the breakdown voltage is kV. The porosity was measured using X-ray computed tomography (CT) technology; the unit of porosity is _____.

2. The method for evaluating the aging resistance performance of generator stator coils in high-altitude environments according to claim 1, characterized in that, k 1 =49.8， k 2 =161.7， k 3 =208.15。 3. A system for evaluating the aging resistance performance of generator stator coils in high-altitude environments, characterized in that, include: The parameter input module is configured to input relevant indicators of the test generator stator coil, including: the breakdown voltage of the test stator coil, the concentration of volatile organic compounds detected under thermo-oxidative aging conditions, thermal conductivity, specific surface area of ​​solid material, porosity, and liquid adsorption performance. The calculation module is configured to evaluate the aging resistance of the generator stator coil in accordance with the method for evaluating the aging resistance of the generator stator coil in high-altitude environments as described in claim 1 or 2.

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