High-pressure sleeve sheath aging evaluation method and system based on feature unevenness

Abstract

The invention discloses a high-pressure sleeve sheath aging evaluation method and system based on feature unevenness, and belongs to the technical field of high-pressure sleeve operation and maintaining.The method comprises the steps that a to-be-tested high-pressure sleeve sheath is sampled, the interior of a sheath body is selected as a reference area, and meanwhile multiple aging feature areas on the surface of the sheath are selected as aging areas; repairing the sampled insulated damaged area, injecting a nano silicon dioxide modified silicone rubber filler, and performing ultraviolet curing; performing group degradation characteristic test and thermal stability characteristic test on the sampled sample to obtain aging characteristic parameters including characteristic peak absorptivity of each group and thermogravimetric residual rate parameters of different temperature points; taking the aging characteristic parameter of the reference area as a reference value, respectively calculating a single parameter deviation degree of each aging area, and calculating a comprehensive aging non-uniformity value; and according to a comparison result of the comprehensive aging non-uniformity value and a preset grading threshold value, outputting an aging grade of the high-voltage sleeve sheath and a corresponding operation and maintenance strategy.

Description

Technical Field

[0001] The present invention belongs to the fields of high voltage and insulation technology, insulation material aging characterization technology, and high-voltage bushing operation and maintenance technology. More specifically, it relates to a method and system for evaluating the aging of a high-voltage bushing sheath based on characteristic unevenness. Background Art

[0002] The Importance of Silicone Rubber Sheaths in High-Voltage Bushings: Silicone rubber is widely used as a sheath material for high-voltage bushings due to its high elasticity, wide temperature resistance, and excellent electrical properties. It effectively protects the insulation structure within the bushing from external environmental factors such as moisture, dust, and chemical corrosion, thereby ensuring the bushing's insulation performance and safe operation.

[0003] Impact of aging on silicone rubber sheaths: However, over long-term operation, silicone rubber sheaths can age due to various factors, including electrical, thermal, and mechanical stresses, as well as ultraviolet (UV) and ozone in the environment. Aging silicone rubber sheaths can experience performance degradation, such as reduced insulation and mechanical properties, surface cracks, and discoloration. This can severely impact the overall performance and operational reliability of the high-voltage bushings, potentially even causing power equipment failures and potentially leading to power accidents.

[0004] Limitations of Existing Assessment Methods: Currently, a variety of methods exist for assessing the aging of silicone rubber sheaths. For example, many existing techniques (such as those based on absolute material property comparisons) rely on precise comparisons with original, unaged samples or factory-standard data. However, for equipment that has been in operation for many years, original material batches are often difficult to obtain, and factory data may be missing or incomplete, making it difficult to guarantee complete consistency with the initial state of the current equipment material. Aging is assessed by observing the degree of discoloration on the silicone rubber surface, but this method is highly subjective, leading to different conclusions among observers and low sensitivity for detecting early-stage aging. While analytical methods using modern instruments such as broadband dielectric spectrometers can provide relatively accurate information, these methods typically require specialized equipment and technicians, are complex to operate, and are costly, making them difficult to routinely apply on-site. Furthermore, methods based on partial discharge detection only provide partial information about the aging process of silicone rubber and struggle to accurately assess aging phenomena caused by factors other than electrical treeing. Therefore, developing a method for assessing the aging status of high-voltage bushing silicone rubber sheaths that overcomes the lack of a reliable reference benchmark and enables scientific, quantitative, and practical assessment is of great practical significance.

[0005] Prior art document 1 (CN114371372A) discloses an evaluation method in the technical field of aging status evaluation of silicone rubber composite insulators. The method collects samples at specific shed positions of the insulator and conducts multiple performance tests. The samples are further subjected to high-temperature thermal oxygen aging tests and then the aging space coordinates are calculated for evaluation. However, the evaluation process must rely on additional long-term high-temperature accelerated aging tests, and the test cycle is long and the process is complicated. At the same time, the method only collects whole samples from a few fixed shed positions at the high-voltage end of the insulator. The sampling strategy is single and lacks representativeness, and it is impossible to effectively capture and evaluate the non-uniformity of the aging status of different parts of the insulator due to local environmental differences.

[0006] Prior art document 2 (CN119339853A) discloses an evaluation method in the technical field of electrical aging status evaluation of casing silicone rubber. The method predicts the electrical aging status by constructing a microscopic molecular model of silicone rubber, applying a simulated electric field, calculating electrical parameters and infrared spectra, and establishing a correlation model. However, its evaluation model is based on a simplified microstructure, which is difficult to accurately reflect the complex characteristics of real materials, affecting the accuracy of the evaluation. At the same time, the method relies on idealized simulated electric field conditions, which are significantly different from the complex and changeable real electric field environment in actual power equipment, resulting in limited applicability of the model. In addition, the method mainly focuses on the effect of a single electric field factor, and fails to fully consider the synergistic aging effects of multiple factors such as heat, ultraviolet rays, and chemical corrosion in actual operation, and the evaluation dimensions are not comprehensive. Its verification is also mainly based on simulation calculations and short-term experiments, and lacks sufficient verification of the actual aging status of long-term service equipment. Summary of the Invention

[0007] In order to solve the deficiencies in the prior art, the present invention provides a method and system for evaluating the aging of a high-voltage bushing based on characteristic non-uniformity.

[0008] The present invention adopts the following technical solutions.

[0009] A first aspect of the present invention provides a method for evaluating the aging of a high-voltage bushing based on characteristic non-uniformity, comprising the following steps:

[0010] Sampling the sheath of the high-voltage bushing to be tested, including selecting the interior of the sheath body as a reference area and selecting multiple aging characteristic areas on the surface of the sheath as aging areas;

[0011] Repair the damaged insulation area after sampling by injecting nano-silica modified silicone rubber filler and UV curing;

[0012] Perform group degradation characteristic tests and thermal stability characteristic tests on the sampled samples to obtain aging characteristic parameters, including the characteristic peak absorption rate of each group and the thermogravimetric residual rate parameters at different temperature points;

[0013] Taking the aging characteristic parameters of the reference area as the reference value, calculate the single parameter deviation of each aging area and the comprehensive aging unevenness value;

[0014] Based on the comparison results of the comprehensive aging unevenness value and the preset classification threshold, the aging grade of the high-voltage bushing sheath and the corresponding operation and maintenance strategy are output.

[0015] Optionally, selecting the reference area and the plurality of aging areas includes:

[0016] The reference area is the position inside the high-voltage bushing body at a set depth from the surface;

[0017] The aging area includes the outer surface of the high-pressure end body, the upper surface of the medium-pressure end shed skirt, and the upper surface of the high-pressure end shed skirt;

[0018] The aging regions are divided based on at least one environmental factor of electric field intensity, ultraviolet radiation intensity, and corona discharge intensity.

[0019] Optionally, sampling the reference area and the aged area includes:

[0020] A micro hollow drill bit with a diameter no greater than the set size is used, along with a sampling device with a depth limit function, to sample the reference area and the aging area. The sampling depth accuracy is within the set accuracy range.

[0021] Optionally, repairing the insulation damaged area after sampling includes:

[0022] A nano-silica modified silicone rubber filler is injected into the sampling hole, wherein the nano-silica modified silicone rubber filler comprises room temperature vulcanized silicone rubber, nano-silica, a silane coupling agent, a cross-linking agent, a photoinitiator, and a plasticizer in a set ratio;

[0023] Use a UV light source to illuminate the filled area for curing.

[0024] Optionally, the group degradation characteristic test of the sampled sample includes:

[0025] Fourier transform infrared spectrometer was used to test the absorbance of the characteristic peaks of the main chain and side chain of silicone rubber in the sample, including the characteristic peak of the Si-O-Si main chain, the characteristic peak of the -CH3 side chain and the characteristic peak of the Si-C interface structure within the set wavenumber range;

[0026] The absorbance of each characteristic peak is calculated based on the measured transmittance value of each characteristic peak, and the absorbance of each characteristic peak of each group in the reference area and each aging area is obtained.

[0027] Optionally, the thermal stability characteristic test of the sampled sample includes:

[0028] Under a nitrogen atmosphere, thermogravimetric analysis was performed at a set temperature rise rate to obtain the thermogravimetric residual rate parameters of the reference area and various aging areas at different test temperature points;

[0029] The test temperature points include multiple temperature points.

[0030] Optionally, calculating the single parameter deviation of each aging area includes:

[0031] For each aging characteristic parameter, the absolute value difference between the test value of the parameter in the aging area sample and the test value of the reference area sample is calculated, and the difference value is divided by the test value of the reference area sample and expressed as a percentage.

[0032] Optionally, calculating the comprehensive aging non-uniformity value includes:

[0033] The single parameter deviation of each aging characteristic parameter is linearly weighted according to the preset weight to generate a comprehensive aging unevenness value;

[0034] The aging characteristic parameters include the Si-O-Si main chain characteristic peak absorption rate, the -CH3 side chain characteristic peak absorption rate, the Si-C interface structure characteristic peak absorption rate and the thermogravimetric residual rate at each temperature point.

[0035] Optionally, outputting the aging level and corresponding operation and maintenance strategy based on the comparison result includes:

[0036] When the comprehensive aging unevenness value is in the first interval where unevenness increases successively, it is judged as mild aging. The corresponding strategy is to strengthen inspections and record data change trends.

[0037] When the comprehensive aging unevenness value is in the second interval where the unevenness increases successively, it is determined to be moderate aging, and the corresponding strategy is local repair or planned replacement of the sheath;

[0038] When the comprehensive aging unevenness value is in the third interval where the unevenness increases successively, it is determined to be severe aging, and the corresponding strategy is to immediately shut down the system and replace the high-voltage bushing sheath.

[0039] A second aspect of the present invention provides a high-voltage bushing sheath aging assessment system based on characteristic non-uniformity. Based on the high-voltage bushing sheath aging assessment system based on characteristic non-uniformity described in the first aspect of the present invention, the system comprises:

[0040] Minimally invasive sampling module for on-site sampling of high-voltage bushings;

[0041] Online repair module, used to inject filler into the insulation damage area after sampling and repair it through UV curing;

[0042] Aging characteristic test module, including a Fourier transform infrared spectrometer and a thermogravimetric analyzer, used to obtain aging characteristic parameters of the sample;

[0043] Data processing and analysis module, used to calculate the single parameter deviation and comprehensive aging non-uniformity of each aging area;

[0044] The evaluation and decision-making module outputs the aging level and operation and maintenance strategy based on the comparison results of the comprehensive aging unevenness value and the preset threshold.

[0045] Compared with the prior art, the beneficial effects of the present invention include at least:

[0046] 1. The aging assessment method based on the autogenous reference provided by the present invention selects the deep region inside the equipment sheath as the reference and calculates the relative deviation of the characteristic parameters of the surface aging region. This method achieves a scientific and quantitative assessment of the aging state of long-term service high-voltage bushings in the absence of original reference samples.

[0047] 2. The multi-dimensional feature fusion evaluation strategy provided by the present invention solves the one-sided evaluation problem caused by the existing technology relying on a single aging indicator by calculating the spatial heterogeneity of the group degradation and thermal stability parameters and determining the classification threshold, and comprehensively reflects the overall aging risk level of the casing and sheath;

[0048] 3. The minimally invasive sampling and online repair collaborative process provided by the present invention uses micro-drills for precise sampling and nano-modified filler UV curing to obtain representative samples from deep layers and surfaces while maintaining the insulation integrity of the equipment, significantly reducing the impact of traditional destructive testing on equipment safety.

[0049] 4. The closed-loop evaluation system from feature testing to operation and maintenance decision-making provided by the present invention outputs a hierarchical operation and maintenance strategy through intelligent comparison of comprehensive aging unevenness values with preset thresholds, greatly improving the accuracy and timeliness of high-voltage bushing aging management. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is an overall flow chart provided according to an embodiment of the present invention;

[0051] Figure 2 is a sampling schematic diagram provided according to an embodiment of the present invention;

[0052] Figure 3 is a characteristic peak test result diagram provided according to an embodiment of the present invention;

[0053] Figure 4 1 is a thermogravimetric curve diagram of four samples provided in accordance with an embodiment of the present invention;

[0054] Figure 5 This is an evaluation sample diagram provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0055] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0056] In embodiment 1, the present invention provides a method for evaluating the aging of a high-voltage bushing based on characteristic non-uniformity, such as Figure 1 As shown, the following steps are included:

[0057] Step 1: Conduct on-site sampling of the high-voltage bushing, including dividing a reference area and multiple aging areas to be tested for sampling.

[0058] Preferably, in step 1, dividing a reference area and multiple aging areas to be tested includes:

[0059] The interior of the high-voltage bushing is used as the reference area, specifically at a depth of 1 mm from the surface, representing the initial state of the material;

[0060] The outer surface of the high-pressure end body, the upper surface of the medium-pressure end shed skirt, and the upper surface of the high-pressure end shed skirt were selected as the aging areas to be tested;

[0061] Specifically, the aging area to be tested is divided based on at least one environmental factor among electric field intensity, ultraviolet radiation intensity and corona discharge intensity, wherein:

[0062] The outer surface of the high-voltage end is an area with high electric field intensity and relatively serious aging;

[0063] The upper surface of the medium-pressure end shed is a concentrated area of ultraviolet radiation and a moderately aged area;

[0064] The upper surface of the high-voltage end shed is the area where corona discharge and ultraviolet radiation are concentrated, and is also the area with the most serious aging.

[0065] Preferably, in step 1, sampling the reference area and the aging area to be tested includes:

[0066] A micro hollow drill bit (diameter ≤ 2mm) is used with a depth limiter to ensure the sampling depth accuracy of ±0.1mm.

[0067] Step 2: Repair the damaged insulation area after sampling by injecting nano-SiO2 modified silicone rubber filler and UV curing.

[0068] Preferably, the step 2 includes:

[0069] The insulation damage caused by sampling is repaired online. Due to the large volume of the high-voltage bushing, local micro-scale sampling can be carried out online without affecting its use.

[0070] Specifically, silicone rubber filler (components of room temperature vulcanized silicone rubber + nano-SiO2) was injected immediately after sampling, and ultraviolet curing technology (wavelength 365nm, power 50W / cm 2 , irradiation for 30s) for rapid repair, and the insulation strength recovery rate after repair is ≥95%.

[0071] Preferably, the nano-silica modified silicone rubber filler in step 2 comprises 85% to 90% by mass of room temperature vulcanized silicone rubber, 5% to 8% by mass of nano-silica, 1% to 2% by mass of a silane coupling agent, 3% to 4% by mass of a cross-linking agent, 0.5% to 1% by mass of a photoinitiator, and 0.5% to 1% by mass of a plasticizer.

[0072] Step 3: Perform group degradation characteristic test and thermal stability characteristic test on the sampled samples to obtain the group characteristic peak absorption rate and thermogravimetric residual rate parameters at different temperature points.

[0073] Preferably, the group degradation characteristic test of the sampled sample comprises:

[0074] The absorbance of the characteristic peak of the Si-O-Si main chain, the characteristic peak of the -CH3 methyl side chain and the characteristic peak of the Si-C interface structure was tested by Fourier transform infrared spectrometer (FTIR). The test range covered the Si-O-Si peak at 1100 to 1000 wavenumbers, the methyl peak at 1260 wavenumbers and the Si-C peak at 788 wavenumbers, and the absorbance of the characteristic peak of each group in the reference area and each aging area was obtained.

[0075] Specifically, the selection of the Si-O-Si main chain characteristic peak, the -CH3 methyl side chain characteristic peak and the Si-C interface structure characteristic peak was obtained through preliminary experiments of the present invention. During the experiment, it was found that the changes in these characteristic peaks after aging were the most significant.

[0076] Furthermore, the scanning range of the Fourier transform infrared spectrometer is 4000~400cm -1 , with a resolution of 4cm -1 .

[0077] Further preferably, the calculation of the gene characteristic peak absorption rate includes:

[0078] W i =1-T i

[0079] Among them, T iIt represents the transmittance of the i-th sample, which can be obtained through testing. Specifically, although infrared spectroscopy cannot perform quantitative analysis on each group, the comparison of the transmittance of its characteristic peak can quantitatively compare the number of each group. Here, the number of each group is compared by the size of the absorbance.

[0080] Preferably, the thermal stability characteristic test of the sampled sample comprises:

[0081] Under a nitrogen atmosphere, thermogravimetric analysis was performed at a temperature rise rate of 30°C / min to obtain the thermogravimetric residual rate parameters of the reference area and various aging areas at different test temperature points;

[0082] The test temperature points include 650°C, 700°C, 750°C and 800°C.

[0083] Specifically, the residual rate of the sample at different temperature points was tested by thermogravimetric analyzer (TGA) to characterize the degree of thermal decomposition of the material and the stability of the filler;

[0084] The TGA test was performed in a nitrogen atmosphere, with an experimental temperature of 25-800° C. and a temperature rise rate of 30° C. / min.

[0085] Step 4: Calculate the single parameter deviation of each aging area respectively, and calculate the comprehensive aging unevenness value through the pre-built calculation model.

[0086] Preferably, in step 4, calculating the single parameter deviation of each aging area includes:

[0087] Single parameter deviation:

[0088]

[0089] Among them, X i is the i-th parameter (such as Si-O-Si absorption rate and 750℃ residue rate). The subscript body represents the sample inside the sheath, that is, the reference area sample sampled in step 1, which serves as the benchmark sample for reference; the subscript surface represents the aged samples at different positions on the surface.

[0090] Preferably, in step 3, generating a comprehensive aging unevenness value according to a preset weight includes:

[0091] The preset weights were determined experimentally, where the Si-O-Si absorption rate weight was 0.3, the methyl absorption rate weight was 0.15, the Si-C absorption rate weight was 0.15, and the thermogravimetric residual rate weight at each temperature point was 0.1;

[0092] The comprehensive aging unevenness value is the result of weighted summation of the deviations of each single parameter according to their weights, and the comprehensive aging unevenness value is calculated as:

[0093]

[0094] Among them, w i is the weight of the i-th parameter.

[0095] It is worth noting that existing aging assessment methods rely on external reference samples. It is usually necessary to compare the aged materials sampled on site with new, unused materials from the same batch or factory standard data. For high-voltage bushings that have been in operation for 10 or 20 years, the silicone rubber materials used may no longer have the original formula, batch materials or original factory data. Even if the original materials / data are available, they cannot be guaranteed to be completely consistent with the initial state of the current equipment materials. Therefore, the existing aging assessment methods lack reliable and comparable absolute reference values, which makes the existing assessment methods based on absolute values difficult to implement on long-term service equipment or the results are unreliable. The self-reference aging assessment method provided by the present invention utilizes the spatial non-uniformity of the aging of the high-voltage bushing sheath, defines the internal area with the least aging relative to the surface area as the reference area, and proposes to calculate the degree of deviation of the characteristic parameter values of each surface aging area relative to the characteristic parameter values of the internal reference area sampled on the same equipment and at the same time, that is, the non-uniformity, completely abandoning the reliance on difficult-to-obtain and unreliable external reference samples.

[0096] Step 5: Based on the comparison result of the comprehensive aging non-uniformity value and the preset grading threshold, the aging grade and operation and maintenance strategy are output.

[0097] Preferably, the step 5 includes:

[0098] When the comprehensive aging unevenness value is less than 15%, it is judged as mild aging. The corresponding strategy is to strengthen inspections and record data change trends.

[0099] When the comprehensive aging unevenness value is between 15% and 35%, it is judged as moderate aging, and the corresponding strategy is local repair or planned replacement of the sheath;

[0100] When the comprehensive aging unevenness value is greater than 35%, it is judged as severe aging, and the corresponding strategy is to immediately shut down and replace the high-voltage bushing sheath.

[0101] The shortcomings of the existing technology include:

[0102] First, significant environmental interference: External factors such as temperature and humidity, electromagnetic noise, and surface contamination severely impact the reliability of test results. Destructive testing, reliance on specialized equipment, and complex operational procedures limit online monitoring and real-time assessment capabilities.

[0103] Second, there is insufficient sensitivity to minor structural changes or initial performance degradation (such as molecular chain breakage and trace moisture intrusion). Due to the lack of a unified quantification standard for aging, assessment results are mostly qualitative or semi-quantitative, making it difficult to support lifespan predictions or provide precise on-site maintenance and decommissioning standards.

[0104] In response to the above shortcomings, the present invention, based on the actual phenomenon of uneven aging of high-voltage bushings, innovatively proposes a quantitative assessment method for high-voltage bushing sheath aging based on characteristic unevenness through minimally invasive sampling + repair at multiple feature positions. By calculating the deviation of multi-position characteristic parameters and designing a grading threshold, it solves the problems of lack of quantitative standards for aging degree and difficulty in supporting life prediction.

[0105] In embodiment 2, the present invention provides a high-voltage bushing sheath aging assessment system based on characteristic non-uniformity. Based on the high-voltage bushing sheath aging assessment method based on characteristic non-uniformity described in embodiment 1, the system includes:

[0106] A minimally invasive sampling module is used to sample the interior of the sheath body of the high-voltage bushing as a reference area and at least three types of typical aging characteristic areas;

[0107] Online repair module, used to inject filler into the insulation damage area after sampling and repair it through UV curing;

[0108] Aging characteristic test module, including Fourier transform infrared spectrometer (FTIR) and thermogravimetric analyzer (TGA), used to obtain characteristic parameters directly related to material degradation and thermal stability;

[0109] Data processing and analysis module, used to calculate the single parameter deviation and comprehensive aging non-uniformity of each aging area;

[0110] The evaluation and decision-making module outputs the aging level and operation and maintenance strategy based on the comparison results of the comprehensive aging unevenness value and the preset threshold.

[0111] In Example 3, the present invention provides an application example of a method for evaluating high-voltage bushing sheath aging based on characteristic non-uniformity. Based on the method for evaluating high-voltage bushing sheath aging based on characteristic non-uniformity described in Example 1, the application example includes:

[0112] ① Carry out on-site sampling of high-voltage bushings, and take samples from the inside of the sheath body (1mm depth from the surface, representing the initial state of the material), the outer surface of the high-voltage end body (the area with high electric field intensity and relatively serious aging), the upper surface of the medium-voltage end shed (the area with concentrated ultraviolet radiation and moderate aging), and the upper surface of the high-voltage end shed (the area with concentrated corona discharge and ultraviolet radiation, the area with the most serious aging).

[0113] Sampling tool: Use a micro hollow drill bit (diameter ≤ 2mm) with a depth limiter to ensure the sampling depth accuracy of ±0.1mm.

[0114] Specifically, if Figure 2 As shown in the figure, 1 represents the inside of the sheath body, 2 represents the outer surface of the high-voltage end body, 3 represents the upper surface of the middle shed skirt, and 4 represents the upper surface of the high-voltage end shed skirt. It should be noted that the high-voltage bushings sampled in this embodiment are samples that have been in operation for more than ten years and have now been retired. Figure 5 shown.

[0115] ② Perform online repair on insulation damage caused by sampling. Due to the large volume of high-voltage bushings, local micro-scale sampling can be performed online without affecting use.

[0116] Specifically: Immediately after sampling, silicone rubber filler (components are room temperature vulcanized silicone rubber + nano-SiO2) is injected, and ultraviolet curing technology (wavelength 365nm, power 50~80W / cm 2 , irradiation for 30 to 60 seconds) for rapid repair, and the insulation strength recovery rate after repair is ≥95%.

[0117] Specifically, the formula of the nano-SiO2 modified silicone rubber filler used in the embodiment of the present invention is shown in Table 1:

[0118] Table 1 Silicone rubber filler formula provided by the embodiment of the present invention

[0119]

[0120] ③ Test the characteristics of aging, for example, the absorption rate of the three characteristic peaks of Si-O-Si, -CH3 and Si-C of the sample, the TGA test residue rate at 650 degrees, 700 degrees, 750 degrees and 800 degrees, etc.

[0121] The characteristic peaks were detected by Fourier transform infrared spectrometer (FTIR) with a scanning range of 4000-400 cm -1 , resolution 4cm -1 Quantitative analysis of characteristic peak absorbance, taking 1100-1000cm -1 The Si-O-Si characteristic peak between the two is located at 1260 cm -1 The characteristic peak of -CH3 at 788cm -1 The Si-C characteristic peak is taken as the group characteristic parameter.

[0122] Specifically, in this embodiment, the base area of the sheath body is set as position 1, the outer surface of the sheath body in the aging area is set as position 2, the upper surface of the middle shed is set as position 3, and the upper surface of the high-pressure shed is set as position 4; the characteristic peak test results of the four positions are as follows: Figure 3 shown.

[0123] Specifically, in this embodiment, the absorption rates of the three characteristic peaks of Si-O-Si, -CH3 and Si-C in the reference area and various aged areas are statistically calculated, as shown in Table 2:

[0124] Table 2 Absorption rates of Si-O-Si, -CH3 and Si-C characteristic peaks in the reference area and various aged areas

[0125] Absorption of characteristic peak <![CDATA[W -CH3 ]]> <![CDATA[W O-Si-O ]]> <![CDATA[W Si-C ]]> Position 1 63.1％ 95.6％ 96.9％ Position 2 25.7％ 76.2％ 66.9％ Position 3 8.2％ 42.2％ 32.9％ Position 4 7.5％ 46.9％ 31.1％

[0126] Among them, TGA test residual rate: nitrogen atmosphere, experimental temperature is 25-800℃, temperature rise rate is 30℃ / min, and the residual rate at 650℃, 700℃, 750℃, and 800℃ is recorded (reflecting the filler stability and thermal decomposition degree);

[0127] Specifically, in this embodiment, the residual rates at 650°C, 700°C, 750°C, and 800°C at four locations are extracted and recorded as shown in Table 3:

[0128] Table 3 Residual rate of test samples at different temperature points in one embodiment of the present invention

[0129] Residual rate Position 1 Position 2 Position 3 Position 4 650 degrees 0.83161 0.81661 0.80492 0.78871 700 degrees 0.76543 0.7251 0.70362 0.67335 750 degrees 0.73129 0.69216 0.67228 0.64352 800 degrees 0.7097 0.67592 0.6567 0.63026

[0130] Specifically, in this embodiment, the thermogravimetric curves of the four samples are as follows: Figure 4 shown.

[0131] ④ Calculate the deviation of the test results of the three places, namely, the outer surface of the high-pressure end body, the upper surface of the medium-pressure end shed, and the upper surface of the high-pressure end shed, from the test results of the internal part of the sheath body (the deviation represents the uneven aging), and weight the settlement results of different parameters according to their importance.

[0132] Specifically, deviation calculation and weight distribution,

[0133] Single parameter deviation:

[0134]

[0135] Among them, X i is the i-th parameter (such as Si-O-Si absorption rate, 750℃ residue rate), the body represents the sample inside the sheath (as a benchmark sample for reference); the surface represents the aged samples at different positions on the surface.

[0136] Specifically, in this embodiment, the single deviations of different characteristic parameters at different positions are calculated as shown in Table 4:

[0137] Table 4 Single deviation of different characteristic parameters at different positions in the aging area

[0138] Absorption rate and residual rate parameters Position 2 Position 3 Position 4 <![CDATA[W -CH3 ]]> 59.27％ 87.00％ 88.11％ <![CDATA[W O-Si-O ]]> 20.29％ 55.86％ 50.94％ <![CDATA[W Si-C ]]> 30.96％ 66.05％ 67.91％ 650 degrees 1.80％ 3.21％ 5.16％ 700 degrees 5.27％ 8.08％ 12.03％ 750 degrees 5.35％ 8.07％ 12.00％ 800 degrees 4.76％ 7.47％ 11.19％

[0139] Comprehensive aging unevenness:

[0140]

[0141] Among them, w i is the weight of the i-th parameter.

[0142] In this example, it can be found that the aging degree at position 4 is the most serious, which can be used as a significant characteristic position to characterize aging. Therefore, by comparing position 4 with position 1, a multi-parameter comprehensive aging unevenness can be obtained. In this example, the weights assigned to different parameters are shown in Table 4:

[0143] Table 4 Weighting and description of different parameters

[0144]

[0145] Finally, the overall aging non-uniformity output is 42.72%. Based on historical data and failure cases, three thresholds are set, as shown in Table 5:

[0146] Table 5 Aging levels and risks corresponding to different comprehensive unevenness

[0147] Aging level Comprehensive unevenness (U) Risk Description Mild <15％ Can continue to operate and strengthen inspection Moderate 15％～35％ Partial repair or planned replacement is required severe >35％ Stop the machine immediately and replace it to prevent breakdown

[0148] The quantitative evaluation value of the bushing aging in the case of the present invention is 42.72%, which is severe aging and should be immediately shut down and replaced to prevent breakdown.

[0149] It is worth noting that the existing aging assessment methods are limited by the difficulty of obtaining original reference samples (for example, in this case, there is no new material from the same batch for the bushing that has been in operation for more than 10 years), resulting in the lack of a quantitative benchmark. The present invention creatively uses the internal area of the bushing sheath body as a self-generated benchmark and constructs a comprehensive aging non-uniformity model by calculating the deviation of characteristic parameters. As shown in this case, even when faced with a long-term service bushing without an original reference sample, a quantitative assessment value of 42.72% can still be output, accurately triggering the shutdown and replacement strategy, solving the problem of aging assessment failure caused by the lack of historical material data in power operation and maintenance.

[0150] Current high-voltage bushing aging assessment technologies primarily rely on physical and chemical testing, electrical analysis, and microstructural observation, but their application has significant limitations. Among existing physical and chemical testing methods, surface color difference analysis is susceptible to interference from material formulation and lighting, and lacks the ability to identify early aging characteristics (such as micron-scale cracks). Mechanical property tests (such as tensile testing) can reflect cross-linked structural degradation (e.g., a 35.22% decrease in tensile strength of a 10kV bushing after nine years of operation), but require destructive sampling and the results lag behind insulation degradation. Hydrophobicity assessment (water spray classification, contact angle measurement) is affected by ambient humidity and surface contamination, making it difficult to standardize and quantify mobility. Among electrical testing methods, partial discharge monitoring is sensitive to macroscopic defects but susceptible to electromagnetic interference, making it incapable of identifying uniform aging. Dielectric loss and capacitance measurements (such as tanδ testing) are insensitive to early aging and rely on comparison with factory data. In practical applications, assessment of long-term service equipment is difficult due to a lack of baseline data. Microstructural analysis (such as SEM observation of powdered layers and filler precipitation) relies on manual sampling and is not representative enough. Although FTIR can detect changes in molecular chains (such as fluctuations in the content of Si-O-Si bonds), its quantitative ability is limited and lacks historical data support.

[0151] Emerging technologies, such as machine learning-driven thermal image classification models, require massive amounts of labeled data, lack real-world sample data, and exhibit poor generalization capabilities. Online monitoring systems, while integrating multiple sensors (for dielectric loss, partial discharge, etc.), suffer from poor long-term stability, high data transmission requirements, and still lack the ability to accurately quantify the extent of aging. These methods commonly suffer from destructive operations, reliance on a single parameter, insufficient quantification capabilities, and limited engineering practicality. These methods struggle to meet the core requirements of high-voltage bushing aging assessment: non-destructive, multi-dimensional integration, and rapid decision-making.

[0152] In response to the above-mentioned defects, the present invention achieves a breakthrough through the following technical reconstruction: first, a micro hollow drill bit (diameter ≤ 2mm) is used for minimally invasive sampling and simultaneous injection of nano-SiO2 modified silicone rubber repair agent. The insulation strength recovery rate after UV curing is ≥95%, avoiding the disadvantages of destructive detection in existing technologies; secondly, FTIR is combined to quantitatively analyze the absorption rates of Si-O-Si, -CH3 and Si-C characteristic peaks (corresponding to main chain breakage, side chain oxidation and interface debonding, respectively), as well as TGA test of multi-temperature point residual rates (reflecting filler stability) to construct a chemical-thermal two-dimensional parameter system; finally, the parameter deviation of each region is calculated based on the inside of the sheath, and the comprehensive aging unevenness value is output after weighted fusion (such as 42.72% at position 4), and three-level thresholds are set (mild <15%, severe >35%) to directly link the operation and maintenance strategy, realizing closed-loop management from detection to decision-making.

[0153] The present disclosure may be a system, method and / or computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for evaluating the aging of a high-voltage bushing based on characteristic non-uniformity, characterized in that: The steps include: Sampling the sheath of the high-voltage bushing to be tested, including selecting the interior of the sheath body as a reference area and selecting multiple aging characteristic areas on the surface of the sheath as aging areas; Repair the damaged insulation area after sampling by injecting nano-silica modified silicone rubber filler and UV curing; Perform group degradation characteristic tests and thermal stability characteristic tests on the sampled samples to obtain aging characteristic parameters, including the characteristic peak absorption rate of each group and the thermogravimetric residual rate parameters at different temperature points; Taking the aging characteristic parameters of the reference area as the reference value, calculate the single parameter deviation of each aging area and the comprehensive aging unevenness value; Based on the comparison results of the comprehensive aging unevenness value and the preset classification threshold, the aging grade of the high-voltage bushing sheath and the corresponding operation and maintenance strategy are output.

2. The method for evaluating high voltage bushing sheath aging based on characteristic non-uniformity according to claim 1, characterized in that: The selected reference area and multiple aging areas include: The reference area is the position inside the high-voltage bushing body at a set depth from the surface; The aging area includes the outer surface of the high-pressure end body, the upper surface of the medium-pressure end shed skirt, and the upper surface of the high-pressure end shed skirt; The aging regions are divided based on at least one environmental factor of electric field intensity, ultraviolet radiation intensity, and corona discharge intensity.

3. The method for evaluating high voltage bushing sheath aging based on characteristic non-uniformity according to claim 1, wherein: The sampling of the reference area and the aged area includes: A micro hollow drill bit with a diameter no greater than the set size is used, along with a sampling device with a depth limit function, to sample the reference area and the aging area. The sampling depth accuracy is within the set accuracy range.

4. The method for evaluating high voltage bushing sheath aging based on characteristic non-uniformity according to claim 1, wherein: The repairing of the insulation damaged area after sampling includes: A nano-silica modified silicone rubber filler is injected into the sampling hole, wherein the nano-silica modified silicone rubber filler comprises room temperature vulcanized silicone rubber, nano-silica, a silane coupling agent, a cross-linking agent, a photoinitiator, and a plasticizer in a set ratio; Use a UV light source to illuminate the filled area for curing.

5. The method for evaluating high voltage bushing sheath aging based on characteristic non-uniformity according to claim 1, characterized in that: The group degradation characteristic test of the sampled sample includes: Fourier transform infrared spectrometer was used to test the absorbance of the characteristic peaks of the main chain and side chain of silicone rubber in the sample, including the characteristic peak of the Si-O-Si main chain, the characteristic peak of the -CH3 side chain and the characteristic peak of the Si-C interface structure within the set wavenumber range; The absorbance of each characteristic peak is calculated based on the measured transmittance value of each characteristic peak, and the absorbance of each characteristic peak of each group in the reference area and each aging area is obtained.

6. The method for evaluating high voltage bushing sheath aging based on characteristic non-uniformity according to claim 5, characterized in that: The thermal stability characteristic test of the sampled sample comprises: Under a nitrogen atmosphere, thermogravimetric analysis was performed at a set temperature rise rate to obtain the thermogravimetric residual rate parameters of the reference area and various aging areas at different test temperature points; The test temperature points include multiple temperature points.

7. The method for evaluating high voltage bushing sheath aging based on characteristic non-uniformity according to claim 6, characterized in that: Calculating the single parameter deviation of each aging area includes: For each aging characteristic parameter, the absolute value difference between the test value of the parameter in the aging area sample and the test value of the reference area sample is calculated, and the difference value is divided by the test value of the reference area sample and expressed as a percentage.

8. The method for evaluating high voltage bushing sheath aging based on characteristic non-uniformity according to claim 7, characterized in that: The calculation of the comprehensive aging non-uniformity value includes: The single parameter deviation of each aging characteristic parameter is linearly weighted according to the preset weight to generate a comprehensive aging unevenness value; The aging characteristic parameters include the Si-O-Si main chain characteristic peak absorption rate, the -CH3 side chain characteristic peak absorption rate, the Si-C interface structure characteristic peak absorption rate and the thermogravimetric residual rate at each temperature point.

9. The method for evaluating high voltage bushing sheath aging based on characteristic non-uniformity according to claim 1, characterized in that: Outputting the aging level and corresponding operation and maintenance strategy based on the comparison results includes: When the comprehensive aging unevenness value is in the first interval where unevenness increases successively, it is judged as mild aging. The corresponding strategy is to strengthen inspections and record data change trends. When the comprehensive aging unevenness value is in the second interval where the unevenness increases successively, it is determined to be moderate aging, and the corresponding strategy is local repair or planned replacement of the sheath; When the comprehensive aging unevenness value is in the third interval where the unevenness increases successively, it is determined to be severe aging, and the corresponding strategy is to immediately shut down the system and replace the high-voltage bushing sheath.

10. A high-voltage bushing sheath aging assessment system based on characteristic non-uniformity, based on the high-voltage bushing sheath aging assessment method based on characteristic non-uniformity according to any one of claims 1 to 9, characterized in that: The system includes: Minimally invasive sampling module for on-site sampling of high-voltage bushings; Online repair module, used to inject filler into the insulation damage area after sampling and repair it through UV curing; Aging characteristic test module, including a Fourier transform infrared spectrometer and a thermogravimetric analyzer, used to obtain aging characteristic parameters of the sample; Data processing and analysis module, used to calculate the single parameter deviation and comprehensive aging non-uniformity of each aging area; The evaluation and decision-making module outputs the aging level and operation and maintenance strategy based on the comparison results of the comprehensive aging unevenness value and the preset threshold.

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