A method for evaluating the degree of insulation aging of a generator stator winding

Abstract

The application relates to the technical field of electrical equipment insulation, and discloses a method for evaluating the insulation aging degree of a generator stator winding. The method uses two-dimensional small-angle X-ray scattering technology to detect and evaluate the insulation aging degree of the generator stator winding. The technology is nondestructive detection, the detection process does not damage the sample, therefore, the data obtained through the whole detection and evaluation process is true and accurate, and can objectively and truly reflect the insulation aging degree of the generator stator winding.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrical equipment insulation, in particular to a method for evaluating the insulation aging degree of a generator stator winding. BACKGROUND

[0002] The existing evaluation methods for the insulation state of a generator stator winding mainly include offline detection and online detection. Offline detection mainly includes some electrical test methods such as insulation resistance, power frequency dielectric loss factor test, and AC voltage withstand test. However, the experimental results obtained by these methods are single, the test results are highly dispersed, and the correlation with the insulation life is not strong. Moreover, the power frequency AC breakdown test is a destructive experiment, which will cause irreversible damage to the sample. Online detection mainly includes partial discharge measurement. However, the measurement results are easily disturbed by the surrounding electromagnetic and noise interference, and the correlation with the insulation aging life is poor.

[0003] For example, Chinese patent CN105137349A discloses a method for evaluating the aging state of the main insulation of a large generator stator winding based on the frequency domain dielectric spectrum method. According to the obtained dielectric loss factor increment, the aging state of the main insulation of the generator stator winding is evaluated. The method disclosed in the patent document is based on electrical means, and the aging state of the generator stator winding is determined by measuring the dielectric loss, partial discharge, and insulation resistance of the winding. However, the three quantities obtained by measurement are highly dispersed, and there is no clear relationship with aging. Therefore, the evaluation result is inaccurate.

[0004] Further, Chinese patent CN112116583A discloses a method for judging and testing the aging of insulation paperboard based on SEM image processing. The microstructure of the SEM image of the insulation paperboard is analyzed by using image processing technology, which provides data support for improving the service life of the insulation paperboard and manufacturing new insulation paperboard. The patent relies on the test technology of a scanning electron microscope to obtain the 3D morphology of the main edge by 3D reconstruction through image recognition, and finally judges the state of the main edge. However, the test of the scanning electron microscope is destructive to the sample. Once the sample is destroyed, its original morphology will change. Therefore, this test is not a non-destructive test, and the results obtained by this test are inaccurate or cannot be used for the generator stator bar.

[0005] On the other hand, in academic papers, an aging evaluation method for evaluating the crosslinking components in the stator winding insulation using infrared spectroscopy and other characterization test techniques is published. For example, the document "Polymer Degradation and Stability 42 (1993) 307-316" uses Raman spectroscopy, 13C NMR carbon spectrum nuclear magnetic resonance test, X-ray photoelectron spectroscopy EPR and infrared spectroscopy IR to characterize the molecular structure changes during the thermal oxidation aging process of the epoxy resin. Directly by reading the changes of the characteristic peak position and intensity on the spectrum, to analyze its aging condition; the document "Nuclear Inst. and Methods in Physics Research B 439 (2019) 1-6" uses ultraviolet-visible spectroscopy UV and X-ray photoelectron spectroscopy EPR to study the aging behavior of the epoxy resin under the action of electromagnetic radiation. By ultraviolet spectroscopy UV to capture the changes of chromophore groups, by EPR test to analyze the changes of free radical content, and then reflect its aging condition. The document "Infrared Spectroscopy Study on the Aging Mechanism of Epoxy in the Stator Insulation of a Large Motor Running for 23 Years, Transactions of Electrical Engineering Technology, 2008, 3, 23, 21" uses infrared spectroscopy to study the aging mechanism of epoxy in the stator insulation of a large motor running for 23 years. They first discuss the influence of sample preparation method on the test results, and then analyze the peak intensity and position on the infrared spectrum to discuss the process and mechanism of epoxy aging. The document "Research Status of Dielectric Response of Main Insulation Aging Performance of Large Motor Stator Bar, Large Motor Technology, 2018" uses dielectric response method to study the main insulation aging performance, and then determines the aging degree from the change of electrical performance. The document "Research on Detection Method of Generator Stator Bar Insulation Based on Isothermal Relaxation Method" uses the bar insulation detection and data analysis method based on isothermal relaxation current method to test the isothermal relaxation current of the main insulation bar, and reflects the change of the aging degree through the change of the electrical performance.

[0006] From the above analysis, it can be seen that there is still a lack of a technology for accurately evaluating the aging degree of the generator stator winding insulation. SUMMARY

[0007] In order to solve the problems and deficiencies existing in the prior art, the present application proposes a method for evaluating the aging degree of the generator stator winding insulation. The method uses two-dimensional small-angle X-ray scattering technology to detect and evaluate the aging degree of the generator stator winding insulation. The technology is a non-destructive testing method, and the detection process will not damage the sample. Therefore, the data obtained during the entire detection and evaluation process is true and accurate, and can objectively and truly reflect the aging degree of the generator stator winding insulation.

[0008] In order to achieve the above-mentioned purposes, the technical solutions of the present application are as follows:

[0009] A method for evaluating the aging degree of a generator stator winding insulation, comprising:

[0010] performing X-CT testing on a sample to be detected of the generator stator winding insulation to obtain porosity P ct0 and average volume of microdefects V ct0 ;

[0011] performing 2D-SAXS testing on the sample to be detected of the generator stator winding insulation to obtain apparent porosity P SAXS0 and average pore size H SAXS0 ;

[0012] immersing the sample to be detected of the generator stator winding insulation in a soaking liquid, then taking it out and wiping the surface clean;

[0013] performing X-CT testing again on the sample to be detected of the generator stator winding insulation after soaking treatment to obtain porosity P ct1 and average volume of microdefects V ct1 of the sample to be detected after soaking;

[0014] performing 2D-SAXS testing again on the sample to be detected of the generator stator winding insulation after soaking treatment to obtain apparent porosity P SAXS1 and average pore size H SAXS1 of the sample to be detected after soaking;

[0015] calculating the aging degree of the generator stator winding insulation according to the porosity, average volume of microdefects, apparent porosity and average pore size of the sample to be detected of the generator stator winding insulation before and after soaking treatment, and the calculation expression of the aging degree of the generator stator winding insulation is specifically as follows

[0016] Parameter D Aging represents the aging degree of the generator stator winding insulation, and the greater the value of the calculated parameter D Aging , the higher the aging degree of the stator winding insulation.

[0017] Compared with the prior art, the method for detecting and evaluating the aging degree of the generator stator winding insulation is non-destructive testing, and the sample will not be damaged in the detection process, so that the data obtained is the most real and accurate, and can objectively and truly reflect the aging degree of the generator stator winding insulation.

[0018] Further, in the present application, the solubility index of the soaking liquid is The boiling point of the soaking liquid is greater than 82℃.

[0019] As preferably, the soaking liquid comprises one or more of benzene, toluene, xylene, cyclohexanone, dichloromethane, ethanol, isopropanol, acetone, pyridine, tetrahydrofuran, 1,2-dichloroethane, n-octanol, isobutanol, dimethylacetamide, carbon tetrachloride, dimethyl ether, dimethyl sulfoxide, chloroform, tetrahydronaphthalene, cyclohexanone, n-propanol, etc.

[0020] Further, in the present application, the soaking time of the sample to be detected is 5s-3600s.

[0021] As preferably, the soaking time of the sample to be detected is 100s-1000s.

[0022] Further, in the present application, the soaking temperature of the sample to be detected is not higher than the boiling point temperature of the soaking liquid.

[0023] As preferably, the soaking temperature of the sample to be detected is 25℃-200℃.

[0024] As preferably, the soaking temperature of the sample to be detected is 30℃-120℃.

[0025] Advantages of the present application:

[0026] (1) The present application uses two-dimensional small-angle X-ray scattering technology to detect and evaluate the aging degree of the generator stator winding insulation. Compared with the prior art, the present application is non-destructive testing, and the sample will not be damaged during the detection process, so the data obtained is the most true and accurate, and can objectively and truly reflect the aging degree of the generator stator winding insulation.

[0027] (2) The present application designs different soaking liquids for the sample state of the generator stator winding insulation, and these soaking liquids have different polarity and different physical properties. In the detection and evaluation process, the difference in the state of the soaking liquid can make the method of the present application have different sensitivity to the winding insulation pores or morphology caused by different situations, so as to further analyze whether the pores are initial defects or pores generated during the aging process. Through the combination of different substances, the method of the present application can more accurately capture the pores caused by aging, and the pores caused by other reasons can be screened out, so as to further improve the accuracy of the method. BRIEF DESCRIPTION OF DRAWINGS

[0028] The foregoing and the following detailed description of the present application will become more apparent when read in conjunction with the following drawings, in which:

[0029] Figure 1 The flow chart of the method of the present application. DETAILED DESCRIPTION

[0030] In order for those skilled in the art to better understand the technical solutions in the present application, the following will further illustrate the technical solutions for achieving the purposes of the present application through several specific embodiments. It should be noted that the technical solutions claimed in the present application include but are not limited to the following embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the scope of protection of the present application.

[0031] Embodiment 1

[0032] The stator bar main insulation is an important component in a large generator, accounting for more than 20% of the generator manufacturing cost, so its condition has an important influence on the normal operation of the generator. In the long-term operation of the generator, the stator bar main insulation will be damaged due to the action of electricity, heat and other factors, so that the generator cannot operate normally and has to be forced to stop production, causing huge losses. Therefore, the aging condition and life prediction and evaluation of the stator bar main insulation have great significance for grasping the operation state of the generator.

[0033] At present, the detection data obtained by the existing evaluation method of the insulation state of the generator stator winding is not very accurate, and cannot reflect the aging degree of the stator winding insulation more truly and objectively, so there is still a lack of a technology for accurately evaluating the aging degree of the generator stator winding insulation.

[0034] Based on this, the embodiment provides an evaluation method for the aging degree of the generator stator winding insulation. The method uses small-angle X-ray technology to detect and evaluate the aging degree of the generator stator winding insulation. The entire detection and evaluation process is non-destructive detection, and the detection process will not damage the sample. Therefore, the data obtained by the entire detection and evaluation process is true and accurate, and can objectively and truly reflect the aging degree of the generator stator winding insulation.

[0035] The embodiment discloses a method for evaluating the aging degree of the insulation of a generator stator winding, and the specific implementation process of the method is as follows. Figure 1 The method specifically includes the following steps:

[0036] Step S101. Perform X-CT test on the generator stator winding insulation sample to be detected, so as to obtain the porosity P ct0 and the average volume of micro-defects V ct0 of the insulation sample to be detected.

[0037] In the present embodiment, it should be noted that the porosity and the average volume of micro-defects of the insulation sample to be detected are obtained by X-CT test, and the entire test standard and test process can be performed according to the conventional method of the experiment, for example, reference can be made to the literature “Duan Siping, Wu Ping, Shi Zhenbang. Determination of thermal conductivity of sprayed super-tough cement-based composite material. Building Material Research and Application. 2021, 43, 11, 77-80”, “Miao Yan-chun, Zhang Yu, SELYUTINA Nina, SMIRNOV Ivan, Deng Ke-zhao. Damage research of recycled thermal insulation concrete after high temperature based on X-CT, Journal of Composite Materials, 2022, 39”.

[0038] In the present embodiment, it should also be noted that the experimental data obtained by the X-CT test can be processed according to the existing theoretical model and theoretical calculation method, and details are not repeated here.

[0039] Step S102. Perform 2D-SAXS test on the generator stator winding insulation sample to be detected, so as to obtain the apparent porosity P SAXS0 and the average pore size H SAXS0 of the insulation sample to be detected.

[0040] In the present embodiment, it should be noted that the apparent porosity and the average pore size of the sample to be detected are obtained by 2D-SAXS test, and the entire test standard and test process can be performed according to the conventional method of the experiment, for example, reference can be made to the literature “Liu Peiyin, Micro-nano structure regulation and performance research of epoxy resin composite material, Master's thesis, Dalian University of Technology, 2018” related to the chapter “SAXS characterization”, and the method described in “Bijin Xiong, Fangxinyu Zeng, Jian Kang, Yongfeng Men. Thermal shrinkage and microscopic shutdown mechanism of polypropylene separator for lithium-ion battery: In-situ ultra-small angle X-ray scattering study. Journal of Membrane Science, 545, 213-22”.

[0041] In the present embodiment, it should also be noted that the experimental data obtained by the 2D-SAXS test can be processed according to the existing theoretical model and theoretical calculation method, and details are not repeated here.

[0042] Step S103. Soak the generator stator winding insulation sample to be detected in the soaking liquid, then take it out and wipe the surface clean.

[0043] Further, in the present embodiment, the soaking liquid for soaking the generator stator winding insulation sample to be detected can be a soaking liquid made of one or more of the following substances, including benzene, toluene, xylene, cyclohexanone, dichloromethane, ethanol, isopropyl alcohol, acetone, pyridine, tetrahydrofuran, 1,2-dichloroethane, n-octanol, isobutyl alcohol, dimethylacetamide, carbon tetrachloride, dimethyl ether, dimethyl sulfoxide, chloroform, tetrahydronaphthalene, cyclohexanone, n-propanol, etc.

[0044] In the present embodiment, it should be noted that the soaking liquid for soaking the generator stator winding insulation sample to be detected has a solubility index of The boiling point of the soaking liquid is greater than 82℃.

[0045] In the present embodiment, if the soaking liquid is a liquid made by mixing multiple substances, the mixing ratio is determined according to actual needs, which will not be described here.

[0046] In the present embodiment, it should also be noted that the soaking time of the sample to be detected in the soaking liquid can be 5s-3600s, and as a preferred, the soaking time of the sample to be detected is 100s-1000s.

[0047] In the present embodiment, it should also be noted that the soaking temperature of the sample to be detected in the soaking liquid is not higher than the boiling point temperature of the soaking liquid, when the soaking liquid is made of only one substance, the soaking temperature is not higher than the boiling point temperature of the substance, when the soaking liquid is made by mixing multiple substances, the soaking temperature of the sample to be detected is not higher than the boiling point temperature of the mixture; in the present embodiment, the soaking temperature of the sample to be detected can be 25℃-200℃.

[0048] Further, as a preferred, the soaking temperature of the sample to be detected is 30℃-120℃.

[0049] Step S104. The generator stator winding insulation sample to be detected after soaking treatment is subjected to X-CT test again, and the porosity P ct1 and the average volume of microdefects V ct1 of the sample to be detected after soaking are obtained.

[0050] Step S105. The generator stator winding insulation sample to be detected after soaking treatment is subjected to 2D-SAXS test again, and the apparent porosity P SAXS1 and the average pore size H SAXS1 of the sample to be detected after soaking are obtained.

[0051] Step S106. Calculate the aging degree of the generator stator winding insulation according to the porosity, average volume of micro-defects, apparent porosity and average pore diameter of the insulation sample to be detected before and after the soaking treatment of the generator stator winding insulation, and the calculation expression is as follows

[0052]

[0053] In the above calculation expression, the parameter D Aging represents the aging degree of the insulation sample to be detected, and the greater the value of the calculated parameter D Aging , the higher the aging degree of the insulation sample to be detected.

[0054] The calculation result of the above parameter value D Aging will not be infinite or infinitesimal, but will be in a relatively stable interval. Therefore, when the sample quantity of the sample to be detected is sufficient, and the aging degree parameter of the generator stator winding insulation obtained by the above method is sufficient, a corresponding generator stator winding insulation aging degree database or analysis chart can be established, such as the relationship between the insulation material, operating environment and operating time of the generator stator winding insulation and the aging degree. When the material, operating environment and operating time of a certain generator stator winding insulation are known, the aging degree and aging trend thereof can be roughly inferred, so as to help the staff to quickly judge the aging degree of the generator stator winding insulation and whether the insulation of the generator stator winding needs to be replaced.

[0055] In the present embodiment, it should be noted that since the X-CT test and the 2D-SAXS test are non-destructive tests, the same sample to be detected can be used for X-CT test and then used for 2D-SAXS test, or two completely same samples to be detected can be used, one for X-CT test and the other for 2D-SAXS test.

[0056] From the basic scientific principle, the stator winding insulation aging → defects and cavities are generated → the defects and cavities generated by the stator winding insulation aging can be detected and characterized by using 2D-SAXS and X-CT. However, the existing technology cannot distinguish the initial manufacturing defects and the newly added defects in the aging process, which leads to the fact that the existing technology cannot accurately evaluate the aging degree of the winding insulation and cannot exclude the error caused by the initial manufacturing defects.

[0057] Therefore, in the embodiment, the defects and cavities of the generator stator winding insulation are detected and characterized by using 2D-SAXS and X-CT tests, and then the generator stator winding insulation is immersed in the corresponding immersion solution. The generator stator winding insulation after immersion is subjected to 2D-SAXS test and X-CT test again. According to the test principles of X-CT and 2D-SAXS, when the defects are immersed by the solution, the interface between the defects and the matrix is considered to be "filled", so that the above detection will not detect the immersed defects, and thus the porosity parameter corresponding to the aging defects can be obtained. Based on the obtained porosity parameter of the aging defects, the aging degree of the generator insulation winding is quantitatively calculated by using the formula designed by the inventor, and the parameter D reflecting the aging degree is obtained. Aging The size of the parameter reflects the aging degree of the winding insulation.

[0058] Embodiment 2

[0059] In the embodiment, the specific generator stator winding insulation material is taken as an example to further explain the method for evaluating the aging degree of the generator stator winding insulation according to the application.

[0060] In the embodiment, sample A is a generator stator winding insulation material with a low aging degree after running for one year, and sample B is a generator stator winding insulation material with a high aging degree after running for 20 years. The aging degrees of the two samples are evaluated according to the following steps.

[0061] The X-CT test is performed on sample A and sample B respectively, and the porosity P ct0 of sample A is 2.5%, and the average volume V ct0 of micro-defects is 0.79 mm 3 ; the porosity P ct0 of sample B is 13.1%, and the average volume V ct0 of micro-defects is 1.33 mm 3 .

[0062] The 2D-SAXS test is performed on sample A and sample B respectively, and the apparent porosity P SAXS0 of sample A is 3.8%, and the average pore size H SAXS0 is 396 μm 3 ; the apparent porosity P SAXS0 of sample B is 17.7%, and the average pore size H SAXS0 is 622 μm 3 .

[0063] The samples A and B are subjected to immersion treatment, and are immersed in isobutyl alcohol solution at 80°C for 800 s. Then, the two samples are taken out and the surfaces are wiped clean.

[0064] X-CT tests were performed again on samples A and B that had undergone soaking treatment. The porosity P of sample A after soaking treatment was measured. ct1 =0.7%, average volume of micro-defects V ct1 =0.74mm 3 The porosity P of sample B after immersion treatment was measured. ct1 =0.9%, average volume of micro-defects V ct1 =0.66mm 3 ;

[0065] The 2D-SAXS test was performed again on samples A and B after the soaking treatment. The apparent porosity P of sample A after soaking treatment was measured. SAXS1 =0.9%, average pore size H SAXS1 =338μm 3 The apparent porosity P of sample B after immersion treatment was measured. SAXS1 =2.7%, average pore size H SAXS1 =222μm 3 ;

[0066] Based on the aging degree calculation formula, the index parameter D, which measures the degree of aging, is calculated. Aging D of sample A and sample B Aging The values ​​are 19.11 and 122.81 respectively. It can be seen that the D of sample A... Aging The lower value compared to sample B indicates that sample A has a lower degree of aging than sample B. This result is consistent with the actual aging patterns of both samples, demonstrating that the evaluation method used in this application yields correct results.

[0067] Example 3

[0068] This embodiment uses another specific sample of generator stator winding insulation material to be tested as an example to further explain the method for evaluating the aging degree of generator stator winding insulation according to this application.

[0069] In this embodiment, sample C is a generator stator winding insulation material with a high degree of aging that has been in operation for 30 years, and sample D is a generator stator winding insulation material with a lower degree of aging that has been in operation for 3 years. The aging degree of the two samples is evaluated according to the following steps.

[0070] X-ray CT was performed on samples C and D respectively to obtain the porosity P of sample C. ct0 =38.8%, average volume of micro-defects V ct0 =8.24mm 3 Porosity P of sample D ct0 =7.9%, average volume of micro-defects V ct0 =13.3mm 3 ;

[0071] 2D-SAXS tests were performed on samples C and C2 respectively to obtain the apparent porosity P of sample C. SAXS0 =29.4%, average aperture H SAXS0 =105μm 3 The apparent porosity P of sample D SAXS0 =2.8%, average pore size H SAXS0 =231μm 3 ;

[0072] Samples C and D were subjected to an immersion treatment by immersing them in a mixture of toluene and cyclohexanone at a temperature of 36°C for 1000 seconds. The molar ratio of toluene to cyclohexanone was 1:1. The two samples were then removed and their surfaces were wiped clean.

[0073] X-CT tests were performed on samples C and D that underwent immersion treatment. The porosity P of sample C after immersion treatment was measured. ct1 =13.3%, average volume of micro-defects V ct1 =5.46mm 3 The porosity P of sample D after immersion treatment was measured. ct1 =15.4%, average volume of micro-defects V ct1 =101mm 3 ;

[0074] 2D-SAXS tests were performed on samples C and D after immersion treatment. The apparent porosity P of sample C after immersion treatment was measured. SAXS1 =15.4%, average aperture H SAXS1 =101μm 3 The apparent porosity P of sample D after immersion treatment was measured. SAXS1 =2.1%, average pore size H SAXS1 =38μm 3 ;

[0075] Based on the aging degree calculation formula, the index parameter D, which measures the degree of aging, is calculated. Aging Among them, the D of sample C and sample D Aging The values ​​are 162.13 and 52.45 respectively. It can be seen that the D of sample C... Aging The higher value of sample C compared to sample D indicates that sample C has a higher degree of aging than sample D. This result is consistent with the actual aging patterns of both samples, demonstrating that the evaluation method used in this application is correct.

[0076] Example 4

[0077] This embodiment takes another specific sample of generator stator winding insulation material to be detected as an example to further explain the method for evaluating the aging degree of generator stator winding insulation.

[0078] In this embodiment, sample E is generator stator winding insulation material with high aging degree and running for 5 years, and sample F is generator stator winding insulation material with low aging degree and running for 2 years but with more initial manufacturing defects. The aging degree of the two samples is evaluated according to the following steps.

[0079] The X-CT test is performed on sample E and sample F respectively, and the porosity P ct0 of sample E is measured as 8.9%, and the average volume V ct0 of micro-defects is measured as 2.4mm 3 ; the porosity P ct0 of sample F is measured as 25.6%, and the average volume V ct0 of micro-defects is measured as 18.8mm 3 .

[0080] The 2D-SAXS test is performed on sample E and sample F respectively, and the apparent porosity P SAXS0 of sample E is measured as 12.8%, and the average pore size H SAXS0 is measured as 539μm 3 ; the apparent porosity P SAXS0 of sample F is measured as 22.4%, and the average pore size H SAXS0 is measured as 464μm 3 .

[0081] The soaking treatment is performed on sample E and sample F, and the two samples are soaked in a mixed liquid of ethanol and dimethyl ether, the soaking temperature is 25℃, the soaking time is 120s, the molar ratio of ethanol and dimethyl ether is 4:1, then the samples are taken out and the sample surface is wiped clean.

[0082] The X-CT test is performed on the two samples after soaking treatment respectively, and the porosity P ct1 of sample E after soaking treatment is measured as 8.5%, and the average volume V ct1 of micro-defects is measured as 2.1mm 3 ; the porosity P ct1 of sample F after soaking treatment is measured as 21.8%, and the average volume V ct1 of micro-defects is measured as 18.5mm 3 .

[0083] The 2D-SAXS test is performed on the two samples after soaking treatment respectively, and the apparent porosity P SAXS1 of sample E after soaking treatment is measured as 4.6%, and the average pore size H SAXS1 is measured as 431μm3 The apparent porosity P of sample F after immersion treatment was measured. SAXS1 =20.7%, average pore size H SAXS1 =455μm 3 ;

[0084] Based on the aging degree calculation formula, the index parameter D, which measures the degree of aging, is calculated. Aging D of samples E and F were obtained. Aging The values ​​are 34.41 and 22.46 respectively. It can be seen that the D of sample E... Aging The higher value compared to sample F indicates that sample E has a higher degree of aging than sample F. This result is consistent with the actual aging patterns of both samples, demonstrating that the evaluation method of this invention is correct.

[0085] The above description is merely a preferred embodiment of this application and does not constitute any limitation on this application. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of this application shall fall within the protection scope of this application.

Claims

1. A method of assessing the degree of insulation aging of a generator stator winding, characterized by, The method comprises the following steps: X-CT testing is performed on a sample of the generator stator winding insulation to be tested to obtain its porosity and the average volume of microdefects ; The 2D-SAXS test is performed on the generator stator winding insulation sample to be detected to obtain its apparent porosity and average pore size ; immersing the generator stator winding insulation sample to be detected into the immersion liquid, then taking it out and wiping the surface clean; The insulating sample of the generator stator winding after soaking treatment is tested again by X-CT to obtain the porosity of the sample after soaking and the average volume of microdefects ; The insulating sample of the generator stator winding after soaking treatment is detected again by 2D-SAXS to obtain the apparent porosity of the sample after soaking and the average pore size ; calculating the aging degree of the generator stator winding insulation according to the porosity, average volume of micro-defects, apparent porosity and average pore diameter of the generator stator winding insulation sample to be detected before and after the immersion treatment; the immersion liquid comprises one or more of the following substances: benzene, toluene, xylene, cyclohexanone, dichloromethane, ethanol, isopropyl alcohol, acetone, pyridine, tetrahydrofuran, 1,2-dichloroethane, n-octanol, isobutyl alcohol, dimethylacetamide, carbon tetrachloride, dimethyl ether, dimethyl sulfoxide, chloroform, tetrahydronaphthalene, cyclohexanone, n-propanol; the calculation expression of the aging degree of the generator stator winding insulation is as follows: 。 2. A method of assessing the degree of insulation aging of a generator stator winding according to claim 1, characterized in that, The solubility index of the infusion is 8.6-12.9 The boiling point of the infusion is greater than 82°C.

3. A method of assessing the degree of insulation aging of a generator stator winding according to claim 1, characterized in that, the immersion time of the sample to be detected is 5s-3600s.

4. A method of assessing the degree of insulation aging of a generator stator winding according to claim 1, characterized in that, the immersion time of the sample to be detected is 100s-1000s.

5. A method of assessing the degree of insulation aging of a generator stator winding according to claim 1, characterized in that, the immersion temperature of the sample to be detected is not higher than the boiling point temperature of the immersion liquid.

6. A method of assessing the degree of insulation aging of a generator stator winding according to claim 1, characterized in that, when the immersion liquid is made of only one substance, the immersion temperature is not higher than the boiling point temperature of the substance.

7. A method of assessing the degree of insulation aging of a generator stator winding according to claim 1, characterized in that, when the immersion liquid is made of a mixture of multiple substances, the immersion temperature of the sample to be detected is not higher than the boiling point temperature of the mixture.

8. A method of assessing the degree of insulation aging of a generator stator winding according to claim 1 or 5, characterized in that, the immersion temperature of the sample to be detected is 25℃-200℃.

9. A method of assessing the degree of insulation aging of a generator stator winding according to claim 1 or 5, characterized in that, the immersion temperature of the sample to be detected is 30℃-120℃.

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