A cottonseed insulating oil transformer fault diagnosis method, device and medium

Abstract

This invention relates to the field of fault diagnosis technology, and discloses a method, equipment, and medium for fault diagnosis of cottonseed oil-insulated transformers. The method includes: obtaining the content of dissolved and free gases in the gases produced by the transformer, and extracting the total hydrocarbon content, the content of each characteristic gas, and the content ratio between each characteristic gas; adjusting the boundaries of the regions corresponding to different fault types in the Duval triangle according to the gas production pattern of cottonseed insulating oil in different temperature ranges, and projecting the content ratio between each characteristic gas into the triangle to determine the fault type of the transformer; determining the temperature range of the transformer, whether the transformer involves deterioration of the oil-paper composite insulation, and the degree of transformer fault based on the content of each characteristic gas and its content ratio; and obtaining the fault diagnosis result of the transformer by combining the fault type, the temperature range corresponding to the fault type, whether the transformer involves deterioration of the oil-paper composite insulation, and the degree of transformer fault.

Description

Technical Field

[0001] This invention relates to the field of fault diagnosis technology, and in particular to a method, equipment and medium for fault diagnosis of cottonseed insulating oil transformers. Background Technology

[0002] As a core hub device in the power system, the insulation condition of transformers directly determines the safe and stable operation of the power grid and the reliability of power supply. Overheating is the most frequent type of fault in transformer operation. If it is not accurately identified in the early stages, it will accelerate the aging and degradation of insulation materials, eventually leading to major accidents such as equipment burnout and power grid outages, causing huge economic losses and social impact.

[0003] Dissolved gas analysis (DGA) is a core technology for transformer fault diagnosis. Its principle is that insulating oil undergoes thermal decomposition under electrothermal stress to generate characteristic gases. The composition, proportion and content of gas vary significantly under different fault types, temperature levels and severity levels, which can be used to determine the fault.

[0004] However, traditional fault diagnosis methods are based on mineral insulating oils, while cottonseed insulating oil, as a green and environmentally friendly natural ester insulating oil, has a molecular structure mainly composed of triglycerides, which is significantly different from mineral oils mainly composed of alkanes / cycloalkanes. Its gas production characteristics are completely different, making traditional methods poorly adaptable. Summary of the Invention

[0005] The purpose of this invention is to provide a method, equipment and medium for fault diagnosis of cottonseed insulating oil transformers, which can solve the problem that the existing technology cannot achieve fault diagnosis of cottonseed insulating oil transformers.

[0006] To solve the above-mentioned technical problems, the present invention provides a fault diagnosis method for cottonseed insulating oil transformers, comprising: The contents of dissolved and free gases in the gases produced by the thermal cracking of cottonseed insulating oil in transformers were obtained, and the total hydrocarbon content, the content of each characteristic gas, and the content ratio between each characteristic gas were extracted from the dissolved and free gases. Based on the gas production pattern of cottonseed insulating oil in different temperature ranges, the boundaries of the regions corresponding to different fault types in the Duval triangle are adjusted, and the content ratios between each characteristic gas are projected onto the regions corresponding to different fault types in the adjusted Duval triangle to determine the fault type of the transformer. The temperature range of the transformer is determined based on the content ratio of each characteristic gas. Whether the transformer is involved in the deterioration of the oil-paper composite insulation is determined based on the content of each characteristic gas in the dissolved gas and free gas. The degree of transformer failure is determined based on the total hydrocarbon content and gas production rate in the dissolved gas and free gas. By combining the transformer's fault type, the temperature range corresponding to the fault type, whether the transformer involves deterioration of the oil-paper composite insulation, and the degree of transformer fault, the fault diagnosis results of the transformer can be obtained.

[0007] Further, the extraction of the total hydrocarbon content, the content of each characteristic gas, and the content ratio between each characteristic gas from the dissolved and free gases includes: The sum of CH4, C2H4, C2H6, and C2H2 in the dissolved and free gases is extracted as the total hydrocarbon content. The contents of CH4, C2H4, C2H6, C2H2, CO, and CO2 in the dissolved and free gases are extracted separately. The ratios of C2H6 / C2H4, C2H2 / C2H4, CH4 / C2H6, CO2 / total hydrocarbon content, and CO / CO2 are calculated as the content ratios between each characteristic gas.

[0008] Furthermore, the Duval triangle includes five regions: a low-temperature overheating region, a medium-temperature overheating region, a high-temperature overheating region, a low-energy discharge region, and a high-energy discharge region, corresponding to five fault types: low-temperature overheating fault, medium-temperature overheating fault, high-temperature overheating fault, low-energy discharge fault, and high-energy discharge fault. The adjustment of the boundaries of the regions corresponding to different fault types in the Duval triangle based on the gas generation patterns of cottonseed insulating oil in different temperature ranges includes: Based on the gas generation pattern of cottonseed insulating oil in different temperature ranges, the boundary line between the low-temperature overheating zone and the medium-temperature overheating zone is shifted 22% downwards towards the bottom of the Duval triangle, the boundary line between the medium-temperature overheating zone and the high-temperature overheating zone is shifted 12% downwards towards the bottom of the Duval triangle, and the boundary line between the low-energy discharge zone and the high-energy discharge zone is shifted 3% to the right of the Duval triangle.

[0009] Furthermore, the process of determining the transformer's temperature range based on the content ratios of various characteristic gases, determining whether the transformer involves deterioration of the oil-paper composite insulation based on the content of each characteristic gas in the dissolved and ionized gases, and determining the transformer's fault severity based on the total hydrocarbon content and gas generation rate in the dissolved and ionized gases, includes: If C2H6 / C2H4>10, C2H2 / C2H4=0, and CH4 / C2H6<0.1, then the transformer's temperature range is 90~300℃, corresponding to a low-temperature overheating fault; if 1 <c2h6 c2h4>10, 0 <C2H2 / C2H4<1、CH4 / C2H6> If the ratio is 0.1, the transformer temperature range is 300~700℃, corresponding to a medium-temperature overheating fault; if C2H6 / C2H4<1, C2H2 / C2H4>1, CH4 / C2H6>1, the transformer temperature range is 700-800℃, corresponding to a high-temperature overheating fault. If the CO and CO2 content in the dissolved and free gases reaches 1.5 times or more of the total gas content produced by cottonseed insulating oil in the same temperature range, the oil-paper composite insulation of the transformer is judged to be deteriorated. If the total hydrocarbon content per liter of gas produced in the cottonseed insulating oil is <500 μL, and the daily increase in gas content per liter of gas is <10 μL, the transformer is determined to have a minor fault; if the total hydrocarbon content per liter of gas produced in the cottonseed insulating oil is 500-2000 μL, and the daily increase in gas content per liter of gas is 10-50 μL, the transformer is determined to have a moderate fault; if the total hydrocarbon content per liter of gas produced in the cottonseed insulating oil is >2000 μL, and the daily increase in gas content per liter of gas is >50 μL, the transformer is determined to have a severe fault.

[0010] Furthermore, the transformer fault diagnosis results are obtained by combining the transformer fault type, the temperature range corresponding to the fault type, whether the transformer involves deterioration of the oil-paper composite insulation, and the degree of transformer fault, including: If the fault type, the fault corresponding to the temperature range, and the fault severity of the transformer are all the same, then the corresponding fault level and whether the transformer involves deterioration of the oil-paper composite insulation will be used as the fault diagnosis result of the transformer.

[0011] Furthermore, the transformer fault diagnosis results are obtained by combining the transformer fault type, the temperature range corresponding to the fault type, whether the transformer involves deterioration of the oil-paper composite insulation, and the degree of transformer fault, including: If the fault type, the fault corresponding to the temperature range, and the fault severity of the transformer are different, then the fault diagnosis result will be the higher fault level and whether the transformer involves deterioration of the oil-paper composite insulation.

[0012] Furthermore, the thermal decomposition of cottonseed insulating oil in the transformer was obtained by simulating the overheating fault of the transformer through a pre-constructed experimental system.

[0013] Furthermore, the simulated temperature range of the experimental system includes a low temperature range of 90-150℃ and a medium-high temperature range of 200-800℃.

[0014] Embodiments of the present invention also provide a computer device, including: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the above-described cottonseed insulating oil transformer fault diagnosis method.

[0015] Embodiments of the present invention also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the above-described method for diagnosing faults in cottonseed insulating oil transformers.

[0016] The fault diagnosis method for cottonseed insulating oil transformers provided by this invention has at least the following beneficial effects: For cottonseed oil-insulating transformers, a dual-channel sampling method is used to collect dissolved and free gases from the thermal decomposition of cottonseed oil. The content and ratio of different characteristic gases are extracted, and the existing Duval triangle boundary is improved by utilizing the gas generation patterns of cottonseed oil in different temperature ranges. The content ratios of each characteristic gas are then projected onto the regions corresponding to different fault types within the adjusted Duval triangle, allowing for the determination of the transformer fault type. This scheme considers the gas generation patterns of cottonseed oil, and the improved Duval triangle is more suitable for diagnosing faults in cottonseed oil-insulating transformers.

[0017] Meanwhile, by determining the content and ratio of different characteristic gases as described above, the temperature range of the transformer, whether it involves the deterioration of the oil-paper composite insulation, and the degree of fault can be determined. Combining this determination result with the determination result determined by the improved Duval triangle, the fault diagnosis of cottonseed insulating oil transformers can be achieved comprehensively, and the accuracy of the diagnosis result is higher. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 A flowchart illustrating a method for diagnosing faults in cottonseed oil transformers provided by this invention. Figure 1 ; Figure 2 A flowchart illustrating a method for diagnosing faults in cottonseed oil transformers provided by this invention. Figure 2 ; Figure 3 A schematic diagram of the Duval triangle coordinate definition provided by the present invention; Figure 4 A schematic diagram of a gas generation experimental platform for medium- and high-temperature overheating faults provided by the present invention; Figure 5 A schematic diagram of a quartz boat containing an oil-paper composite sample provided by the present invention; Figure 6 This invention provides a schematic diagram of the internal heating area of ​​a tubular furnace. Figure 7 A schematic diagram of a low-temperature overheating fault test procedure at 90-150℃ is provided for this invention. Figure 8 A schematic diagram of the internal heating of a tubular furnace provided by the present invention; Figure 9 This invention provides a schematic diagram of the gas generation results in a low-temperature overheating fault of mineral insulating oil. Figure 10 This invention provides a schematic diagram illustrating the appearance changes of a mineral insulating oil paper sample at different temperatures. Figure 11 A schematic diagram of the results of a pure cottonseed insulating oil sample provided by the present invention; Figure 12 This is a schematic diagram of the results of a cottonseed insulating oil-paper composite sample provided by the present invention; Figure 13 This is a schematic diagram of the detection results of free gas in cottonseed insulating oil provided by the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] The technical solutions provided by the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0022] One embodiment of the present invention relates to a fault diagnosis method for cottonseed insulating oil transformers. The specific process of the fault diagnosis method for cottonseed insulating oil transformers in this embodiment can be as follows: Figure 1 As shown, it includes: Step 101: Obtain the content of dissolved gas and free gas in the gas produced by the thermal cracking of cottonseed insulating oil in the transformer, and extract the total hydrocarbon content, the content of each characteristic gas, and the content ratio between each characteristic gas in the dissolved gas and free gas.

[0023] Specifically, the sum of CH4, C2H4, C2H6, and C2H2 in the dissolved and free gases is extracted as the total hydrocarbon content. The contents of CH4, C2H4, C2H6, C2H2, CO, and CO2 in the dissolved and free gases are extracted separately. The ratios of C2H6 / C2H4, C2H2 / C2H4, CH4 / C2H6, CO2 / total hydrocarbon content, and CO / CO2 are calculated as the content ratios between each characteristic gas.

[0024] Step 102: Based on the gas production pattern of cottonseed insulating oil in different temperature ranges, adjust the boundaries of the regions corresponding to different fault types in the Duval triangle, and project the content ratios between each characteristic gas onto the regions corresponding to different fault types in the adjusted Duval triangle to determine the fault type of the transformer.

[0025] The Duval triangle comprises five regions: a low-temperature overheating region, a medium-temperature overheating region, a high-temperature overheating region, a low-energy discharge region, and a high-energy discharge region, corresponding to five fault types: low-temperature overheating fault, medium-temperature overheating fault, high-temperature overheating fault, low-energy discharge fault, and high-energy discharge fault. Based on the gas generation patterns of cottonseed insulating oil in different temperature ranges, the boundary line between the low-temperature and medium-temperature overheating regions is shifted 22% downwards towards the bottom of the Duval triangle, the boundary line between the medium-temperature and high-temperature overheating regions is shifted 12% downwards towards the bottom of the Duval triangle, and the boundary line between the low-energy and high-energy discharge regions is shifted 3% to the right of the Duval triangle.

[0026] Step 103: Determine the temperature range of the transformer based on the content ratio between each characteristic gas; determine whether the transformer is involved in the deterioration of the oil-paper composite insulation based on the content of each characteristic gas in the dissolved gas and free gas; and determine the degree of transformer failure based on the total hydrocarbon content and gas production rate in the dissolved gas and free gas.

[0027] Specifically, if C2H6 / C2H4>10, C2H2 / C2H4=0, and CH4 / C2H6<0.1, then the transformer's temperature range is 90~300℃, corresponding to a low-temperature overheating fault; if 1 <c2h6 c2h4>10, 0 <C2H2 / C2H4<1、CH4 / C2H6> If the ratio is 0.1, the transformer temperature range is 300~700℃, corresponding to a medium-temperature overheating fault; if C2H6 / C2H4<1, C2H2 / C2H4>1, CH4 / C2H6>1, the transformer temperature range is 700-800℃, corresponding to a high-temperature overheating fault.

[0028] If the CO and CO2 content in the dissolved and free gases reaches 1.5 times or more of the total gas content produced by cottonseed insulating oil in the same temperature range, the oil-paper composite insulation of the transformer is deemed to be deteriorated.

[0029] If the total hydrocarbon content per liter of gas produced in the cottonseed insulating oil is <500 μL, and the daily increase in gas content per liter of gas is <10 μL, the transformer is determined to have a minor fault; if the total hydrocarbon content per liter of gas produced in the cottonseed insulating oil is 500-2000 μL, and the daily increase in gas content per liter of gas is 10-50 μL, the transformer is determined to have a moderate fault; if the total hydrocarbon content per liter of gas produced in the cottonseed insulating oil is >2000 μL, and the daily increase in gas content per liter of gas is >50 μL, the transformer is determined to have a severe fault.

[0030] Step 104: Based on the transformer's fault type, the temperature range corresponding to the fault type, whether the transformer involves deterioration of the oil-paper composite insulation, and the degree of transformer fault, obtain the transformer fault diagnosis result.

[0031] Specifically, if the fault type, the fault corresponding to the temperature range, and the fault severity of the determined transformer are all of the same fault level, then the corresponding fault level and whether the transformer involves deterioration of the oil-paper composite insulation will be used as the fault diagnosis result of the transformer.

[0032] If the fault type, the fault corresponding to the temperature range, and the fault severity of the transformer are different, then the fault diagnosis result will be the higher fault level and whether the transformer involves deterioration of the oil-paper composite insulation.

[0033] The following is a detailed description of the implementation details of the cottonseed insulating oil transformer fault diagnosis method in this embodiment. The following content is only for the convenience of understanding and is not necessary for implementing this solution.

[0034] This embodiment integrates the improved Duval triangle method, the non-coded ratio method, and the multi-dimensional threshold method to construct a multi-feature fusion comprehensive diagnostic method suitable for cottonseed oil. The core process is as follows: Figure 2 As shown.

[0035] First, under transformer operation or simulated overheating fault conditions, two types of raw data are collected simultaneously. For dissolved gas data in the oil, the headspace method or mechanical oscillation method is used. Transformer oil samples are extracted and analyzed by gas chromatography to obtain the volume fraction or mass concentration of each characteristic gas. For free gas data, gases are collected from the top of the transformer oil conservator, gases released at the fault point, or gases from the top of reagent bottles in the experimental setup. These are directly detected by gas chromatography to obtain the concentration of each characteristic gas in its free state. For both types of data, information such as sampling time, oil temperature, oil replenishment, oil filtration operation records, and equipment operating status must be recorded as the basis for subsequent calibration and analysis.

[0036] Secondly, the original data is normalized and quantified, and the dissolved and free gas data in the oil are merged to obtain corrected net gas production data. This aims to eliminate distortions caused by gas escape, oil temperature fluctuations, and oil replenishment / filtration operations, obtaining net gas production data directly related to the fault. Dissolved gas concentration is usually expressed in μL / L, and free gas in μL / L or ppm. Based on the ideal gas law, the free gas concentration is converted to the volume fraction under standard conditions of 20℃ and 101.325kPa, according to the sampling temperature and pressure. Simultaneously, the dissolved gas concentration in the oil is converted to the gas content per unit volume of oil under standard conditions, eliminating the influence of temperature and pressure differences. If oil replenishment or filtration operations are performed, the gas concentration before and after the operation needs to be reversed based on the replenishment amount and the gas dilution ratio in the oil to restore the true gas increment caused by the fault and avoid concentration distortion caused by changes in oil volume. After correction, the dissolved gas content is multiplied by the oil volume to obtain the total dissolved gas content; the free gas concentration is multiplied by the gas space volume to obtain the total free gas content; the two are added together to obtain the total gas volume generated by the fault, and then converted back to the gas concentration per unit volume of oil to obtain the corrected net gas production data, in μL / L.

[0037] Based on the corrected net gas production data, diagnostic characteristic parameters applicable to cottonseed oil are extracted, including total hydrocarbon content (the sum of CH4, C2H4, C2H6, and C2H2) and the proportion of each characteristic gas. The volume fractions of CH4, C2H4, C2H6, and C2H2 are calculated using the total combustible gas (total hydrocarbons and H2) as the denominator for subsequent Duval triangle localization. Considering the characteristic of cottonseed oil having C2H6 as the dominant hydrocarbon gas, the following key ratios are calculated: R1 = C2H6 / C2H4, R2 = C2H2 / C2H4, R3 = CH4 / C2H6, R4 = CO2 / total hydrocarbons, and R5 = CO / CO2. Specifically, R1 distinguishes between low-temperature and medium-temperature overheating, R2 distinguishes between medium-temperature and high-temperature overheating, R3 distinguishes the dominant gas characteristics of different oil types, R4 distinguishes between cottonseed oil and mineral oil (typically 10-20 for cottonseed oil), and R5 is used for identifying oil-paper composite faults.

[0038] To address the poor applicability of traditional Duval triangles to cottonseed oil, boundary corrections and coordinate adaptations were performed based on the proportion of characteristic gases in cottonseed oil. The triangle coordinates are defined as follows: Figure 3 As shown, the X-axis represents the relative content of CH4, the Y-axis represents the relative content of C2H4, and the Z-axis represents the relative content of C2H2. Based on the gas production patterns of cottonseed oil in different temperature ranges, the fault region boundaries of the traditional Duval triangle are modified. For the low-temperature overheating zone (T1), the traditional T1 / T2 boundary is shifted 22% downwards towards the bottom of the triangle to accommodate the extremely high C2H6 content in the low-temperature segment of cottonseed oil. For the medium-temperature overheating zone (T2), the T2 / T3 boundary is shifted 12% downwards towards the bottom of the triangle to correct the distribution deviation where C2H6 is still dominant in the medium-temperature segment of cottonseed oil. For the discharge zone (D1 / D2), the D1 / D2 boundary is shifted 3% to the right to accommodate the rapid C2H2 generation characteristic of cottonseed oil after 600℃. The calculated proportions of the three characteristic gases are projected onto the improved triangle to preliminarily determine the fault regions of the data points: T1 (low-temperature overheating), T2 (medium-temperature overheating), T3 (high-temperature overheating), and D1 / D2 (discharge fault), thus completing the preliminary location of the fault type.

[0039] Based on the initial location using graphical methods, a multi-dimensional comprehensive judgment is conducted by combining cottonseed oil-specific ratio criteria, oil-paper composite rules, and severity thresholds. The core ratios R1-R5 extracted from S3 are compared with a preset criterion library. If R1>10, R2=0, and R3<0.1, it corresponds to a low-temperature overheating fault of 90~300℃; if R1=10, R2=0, and R3<0.1, it corresponds to a fault of 100℃. <R1<10、0<R2<1、R3> A value of 0.1 corresponds to a medium-temperature overheating fault at 300-700℃; R1<1, R2>1, and R3>1 correspond to a high-temperature overheating fault at 700-800℃. If the CO and CO2 concentrations reach 1.5 times or more the gas production level of a pure oil system at the same temperature, it is judged as deterioration of the oil-paper composite insulation. The fault involves not only the thermal decomposition of the oil but also the pyrolysis of the cellulose in the insulating paper. Based on the total hydrocarbon content and gas production rate, the fault is divided into three levels. If the total hydrocarbon content is <500μL / L and the gas production rate is <10μL / (L・d), it is a mild fault; if the total hydrocarbon content is 500-2000μL / L and the gas production rate is between 10-50μL / (L・d), it is a moderate fault; if the total hydrocarbon content is >2000μL / L and the gas production rate is >50μL / (L・d), it is a severe fault. By combining the above three types of rules, a multi-dimensional result is obtained, including fault type, temperature range, whether oil and paper are combined, and severity.

[0040] Because the graphical method, ratio method, and threshold method may yield inconsistent results, this step sets up consistency checks and priority rules. If the results of the graphical method for location, the ratio method for judgment, the oil-paper composite rule, and the severity classification are completely consistent, a unified diagnostic conclusion will be directly output. If there are inconsistencies, the highest risk level will be prioritized: for example, if the graphical method determines it as T1 low-temperature overheating, while the ratio method determines it as T2 medium-temperature overheating, then it will be output as medium-temperature overheating. If there is a characteristic of increased C2H2, it will be prioritized as high-temperature overheating or a discharge fault. The final output includes the fault type, the corresponding temperature range, whether it involves oil-paper composite degradation, the severity, and the corresponding maintenance recommendations.

[0041] This embodiment is based on the 500℃ oil-paper composite overheating simulation experiment data, and fully reproduces the diagnostic process of the cottonseed insulating oil transformer fault diagnosis method of this embodiment, verifying its applicability in cottonseed oil transformer fault diagnosis.

[0042] S1: Obtain raw gas generation data. A simulated overheating fault of cottonseed oil-paper composite insulation at 500℃ was performed. The system was heated for 5 minutes, and dissolved and free gas data were collected simultaneously. The results are shown in Table 1.

[0043] Table 1. Raw Gas Production Data S2: Data correction and merging to obtain net gas production data. According to the ideal gas law, the free gas sampled at 40℃ is converted to the standard state at 20℃: H2=41, CH4=72, C2H4=57, C2H6=87, C2H2=2.7, CO=203, CO2=3550.

[0044] S3: Extraction of key characteristic parameters specific to cottonseed oil. The total hydrocarbon content was 1250.7 μL / L, CH4 accounted for 52.3%, C2H4 accounted for 45.8%, and C2H2 accounted for 1.96%. The core ratios were R1=1.45, R2=0.043, R3=0.788, R4=11.55, and R5=0.094. Among them, R4 was in the range of 10-20, which is consistent with the characteristics of cottonseed oil rather than mineral oil.

[0045] S4: Improved Duval Triangle Fault Region Location. In the traditional Duval triangle, this point is located near the boundary between T2 (intermediate overheating) and T3 (high-temperature overheating), which is easily misjudged as a high-temperature fault. The T2 / T3 boundary of this invention is shifted down by 12%, which is adapted to the distribution deviation of cottonseed oil in the intermediate temperature range, where C2H6 is still the main component. This point falls completely into the T2 intermediate overheating zone, and is initially located as an intermediate overheating fault.

[0046] S5: Multi-dimensional comprehensive judgment. R1=1.45 in the 1-10 range, R2=0.043 in the 0-1 range, R3=0.788>0.1, which meets the medium-temperature overheating criterion, corresponding to a temperature range of 300-700℃. The CO and CO2 concentrations are 1.6 times the gas production content of the pure oil system under the same temperature overheating fault simulation, reaching 1.5 times the threshold, and are judged as deterioration of oil-paper composite insulation; the total hydrocarbon content of 1250.7μL / L is in the 500-2000μL / L range, which is in the 10-50μL / (L・d) range, and is judged as a moderate fault.

[0047] S6: Consistency Verification and Conclusion Output. The results of the graphical method for location, the ratio method for judgment, and the severity classification are consistent and conflict-free. The final diagnostic conclusion is: Fault type: Medium-temperature overheating fault; Temperature range: 300-700℃; Fault severity: Moderate; Oil-paper composite fault: Yes. This result completely matches the simulated 500℃ oil-paper composite overheating condition, verifying the accuracy of the method of this invention in diagnosing overheating faults in cottonseed oil transformers.

[0048] In some embodiments, the present invention also provides a high-precision, standardized experimental simulation method for overheating fault gas generation in cottonseed insulating oil, covering the entire temperature range. This method addresses the problem that existing technologies cannot be adapted to cottonseed insulating oil. Through standardized sample preparation processes and parameter optimization, it achieves accurate simulation of overheating faults in cottonseed insulating oil. A full-temperature-range simulation system of 90℃-800℃ is constructed, with the low-temperature range (90-150℃) reproducing long-term overheating conditions and the medium-high temperature range (200-800℃) reproducing localized instantaneous overheating conditions. Combined with PID precise temperature control and operating condition matching parameters, precise control within a ±5℃ error range of the hot spot temperature is achieved, solving the problems of incomplete temperature range coverage and insufficient temperature control accuracy. A dual-path acquisition system for dissolved and free gases completely captures all gas components generated by overheating faults, avoiding diagnostic biases caused by missing information and solving the problem of incomplete gas generation information acquisition. It standardizes the entire process from sample pretreatment and atmosphere control to gas acquisition, clarifies the range of key parameters, and ensures that the relative standard deviation of parallel experiments is ≤5%, improving the reliability and comparability of experimental results and solving the problem of poor experimental repeatability. It establishes the correspondence between cottonseed insulating oil, overheating temperature range, and gas generation characteristic parameters, forming a characteristic parameter system and fault classification method that can be directly used for transformer overheating fault diagnosis, thus overcoming the shortcomings of existing technologies in supporting accurate DGA diagnosis of cottonseed oil transformers.

[0049] This embodiment achieves its purpose through a technical approach of modular system construction, differentiated temperature zone design, and standardized operation throughout the entire process: A heating simulation module is constructed with a tubular furnace as the core, complemented by modules for sample preparation, atmosphere control, and gas collection and detection. Differentiated parameters are designed for long-term overheating at low temperatures of 90-150℃ and instantaneous overheating at medium-high temperatures of 200-800℃. Overheating fault simulations of cottonseed oil are conducted in different fault temperature ranges. Oxidation interference is avoided through anaerobic atmosphere control, and information integrity is ensured through dual-channel gas collection. Ultimately, the gas production characteristic parameters of cottonseed oil in different overheating temperature ranges are established, which can be directly used for diagnosing the type and severity of transformer overheating faults.

[0050] Specifically, the experimental system in this embodiment consists of four main modules, each with a clearly defined structure, function, and connection relationship. A schematic diagram of the overall structure can be found here. Figure 4 The details of the core components are as follows: Sample preparation module: includes a vacuum drying oven, a vacuum impregnation tank, etc. Figure 5 The equipment shown includes a 240mL quartz boat, a 500mL sealed glass bottle, and an electronic balance. Its core function is to achieve standardized preparation of pure oil and oil-paper composite samples, eliminating the influence of differences in raw material pretreatment on experimental results.

[0051] Heating simulation module: includes a constant temperature chamber and a tubular resistance furnace. The constant temperature chamber is used for long-term overheating simulation at low temperatures of 90-150℃, and the tubular furnace is used for instantaneous overheating simulation at medium and high temperatures of 200-800℃. Its heating area is a hollow tubular structure that can accommodate a quartz boat and form a point-like temperature field consistent with the actual fault of a transformer. The matching PID temperature control system supports precise setting and real-time display of heating rate, target temperature, and holding time. Atmosphere control module: includes nitrogen cylinder, gas flow meter, PTFE gas delivery tube. Its core function is to create an oxygen-free experimental environment to avoid interference from gas generation due to oxidation of insulating oil, while maintaining a slight positive pressure in the system to prevent air from entering. Gas Acquisition and Detection Module: Includes a 500mL reagent bottle, a 50mL sampling syringe, and a gas chromatograph. Its core function is to simultaneously collect dissolved and free gases in oil to achieve quantitative detection of characteristic gases. Module Connections: In the low-temperature overheating fault simulation experiment, the oil-paper sample in the sealed glass bottle is directly placed into the constant temperature chamber, and the gas acquisition module is connected to the glass bottle via a sampling syringe; in the medium-high temperature simulation experiment, the atmosphere control module is connected to the inlet of the tube furnace via a gas delivery tube, and the reagent bottle of the gas acquisition module is connected to the outlet of the tube furnace via a gas delivery tube, with the quartz boat placed in the... Figure 6 The heating area inside the tubular furnace shown forms a closed gas path circulation: "nitrogen cylinder → gas flow meter → tubular furnace inlet → tubular furnace heating area → tubular furnace outlet → reagent bottle".

[0052] The core innovation of this embodiment lies in the standardized process design and differentiated parameter adaptation. The specific steps are as follows: Standardized sample preparation: No. 25 transformer oil was used as the mineral insulating oil, refined cottonseed oil was used as the vegetable insulating oil, and BZZ125 kraft paper was used as the insulating paper, cut to a size of 4.5cm×8cm. The insulating oil was dried in a vacuum drying oven at 100℃ for 24 hours to remove moisture and dissolved gases. The insulating paper was dried at 110℃ and normal pressure for 12 hours to remove moisture. 100g of pretreated insulating oil was weighed using an electronic balance, poured into a quartz boat, sealed, and set aside. The insulating oil and insulating paper were weighed at a weight ratio of 15:1. The insulating paper was placed in a vacuum impregnation tank and impregnated with insulating oil for 12 hours to ensure that the insulating paper was fully saturated. After impregnation, the paper was dispensed into 500mL sealed glass bottles (250mL of oil and 16.7g of paper, suitable for low-temperature experiments) or quartz boats (100g of oil and 6.7g of paper, suitable for medium- and high-temperature experiments).

[0053] Simulation of overheating fault at low temperatures of 90-150℃: (e.g.) Figure 7 As shown, the oil-paper sample in the sealed glass bottle was placed in the uniform temperature zone in the middle of the constant temperature chamber to ensure temperature uniformity. The target temperature of the constant temperature chamber was set (90℃ / 120℃ / 150℃), the heating rate was 5℃ / min, and the holding time was 192h (matching the duration of a long-term overheating fault in a transformer). After the holding time was completed, the sample was allowed to cool naturally to room temperature. 40mL of oil sample was extracted using a sampling syringe, and 10mL of free gas was extracted from the top of the glass bottle at the same time. The composition and content of dissolved and free gases were detected using a gas chromatograph, and the data were recorded.

[0054] Simulation of overheating faults at low, medium, and high temperatures (200-800℃): A pure oil / oil paper sample loaded in a quartz boat is pushed into the central heating zone of a tube furnace, ensuring the sample is completely centered on the point temperature field; the gas path is connected (nitrogen cylinder → flow meter → tube furnace → reagent bottle), and the seal is checked; the nitrogen cylinder is opened, the flow rate is adjusted to 80 mL / min, and the gas path and tube furnace are purged for 20 minutes to remove air. The flow rate is then reduced to 5 mL / min, maintaining a slight positive pressure; the tube furnace heating rate is set to 10℃ / min, and the holding time is set according to the target temperature (close to the actual fault duration): 200℃ for 2 hours, 300℃ for 15 minutes, 40℃ for... The temperature was maintained at 0℃ for 10 min, 500℃ for 5 min, 600℃ for 3 min, 700℃ for 2 min, and 800℃ for 1.5 min. The temperature was automatically timed after reaching the target temperature, and the power was turned off after the holding period. A slight positive pressure of nitrogen was maintained, and the mixture was allowed to cool naturally to room temperature. Gases generated during overheating entered the reagent bottle through the gas path, partially dissolving in fresh insulating oil and partially existing as free gas at the top of the bottle. 40 mL of oil sample was extracted using a sampling syringe (to detect dissolved gases), and 10 mL of free gas was simultaneously extracted from the top of the reagent bottle. The components and contents of both gases were quantitatively detected using a gas chromatograph, and the combined data yielded a complete gas production pattern.

[0055] Repeatability verification process: Set up 3 parallel experiments for each temperature point and each sample type (pure mineral oil / oil paper, pure cottonseed oil / oil paper), calculate the average gas content and relative standard deviation (RSD), ensure that RSD ≤ 5%, and verify the reliability of the experimental results.

[0056] This embodiment uses No. 25 mineral insulating oil and cottonseed insulating oil as examples to fully reproduce the entire process of this patented technical solution, verifying the feasibility, repeatability, and adaptability of the solution. All operations in the experiment followed the process parameters of the aforementioned technical solution, and the test results can accurately characterize the gas generation patterns of the two types of insulating oil under different overheating faults.

[0057] Simulation of overheating fault of vegetable insulating oil at low temperature (90-150℃): Cottonseed insulating oil was selected as the oil sample, and BZZ125 kraft paper was selected as the paper sample. The paper was prepared at an oil-to-paper weight ratio of 15:1. Figure 8 The oil-paper composite samples shown totaled 36, each containing 250 mL of oil and 16.7 g of paper. They were sealed in 500 mL glass bottles and placed in constant temperature incubators set at 90℃, 120℃, and 150℃ respectively. One sample was taken out every 48 hours for dissolved gas detection in the oil.

[0058] Gas production results under different heating times are as follows Figure 9 As shown in (a) and (b), (a) represents hydrocarbon gases and H2 in cottonseed oil at 90℃, and (b) represents CO and CO2 in cottonseed oil at 90℃. It can be seen that six characteristic gases—CH4, C2H4, C2H6, H2, CO, and CO2—were present in the cottonseed insulating oil during heating, while C2H2 was not detected. This is because the cellulose in the insulating paper undergoes thermal decomposition at high temperatures, generating a large amount of CO2. The CO2 production is far greater than the production of hydrocarbon gases and H2, with the CO2 content in cottonseed oil being 15-20 times the total hydrocarbon content.

[0059] Simulation of overheating fault of mineral insulating oil at low temperature of 200-800℃: Experiments were conducted on pure insulating oil and oiled paper insulation separately. The sample was placed in a quartz boat and placed in the heating zone of a tube furnace. A reagent bottle containing insulating oil was connected to one side of the tube furnace, and a nitrogen cylinder was connected to the other side. Nitrogen gas was purged before the experiment to ensure a pure gas environment within the apparatus. The temperature control device was adjusted, and timing began after the simulated temperature was reached. After heating was completed and the sample cooled to room temperature, the changes in the appearance of the sample inside the quartz boat were observed. Insulating oil was extracted from the reagent bottle, and the dissolved gas content in the oil was measured.

[0060] Appearance changes of mineral insulating paper samples as follows Figure 10 As shown, the mineral oil paper insulation sample showed no significant changes at 200℃; at 300℃, the insulating oil began to vaporize and the insulating paper became obviously carbonized; at 400℃, the insulating oil had completely vaporized and the insulating paper began to wrinkle; at 800℃, the heating area inside the tubular furnace was completely contaminated.

[0061] Subsequently, the dissolved gas content in the insulating oil was measured by extracting samples from the reagent bottle. Because the heating time varied in the overheating fault simulation experiments at different temperatures, the total content of gases generated by the fault could not be directly compared. Therefore, only the relative content of each characteristic gas generated by the fault was compared and analyzed. The results for the two types of pure insulating oil samples are as follows: Figure 11 As shown in the figure. Among them, (a) represents cottonseed oil hydrocarbon gases and H2, and (b) represents cottonseed oil CO and CO2.

[0062] As shown in the figure, the relative content of various hydrocarbon gases in cottonseed oil does not change much with the increase of fault temperature. The main characteristic gas is C2H6, with a relative content of about 60%.

[0063] Results of cottonseed insulating oil-paper composite insulation samples are as follows: Figure 12 As shown in the figure, (a) represents the hydrocarbon gases and H2 from cottonseed oil, and (b) represents the CO and CO2 from cottonseed oil. As can be seen from the figure, the H2 content of cottonseed oil is relatively high during low-temperature faults but gradually decreases with increasing temperature. The proportion of C2H6 suddenly increases at 400℃ and then stabilizes at 50%. The hydrocarbon gas content of oil-paper insulation is basically the same as that of pure oil, but the CO and CO2 content is 1.5 times that of pure oil. This is because the cellulose contained in the insulating paper undergoes a thermal decomposition reaction. When the temperature exceeds 200℃, cellulose undergoes pyrolysis, producing a large amount of CO, CO2, H2O, and a small amount of hydrocarbon gases. After reaching 470℃, coke will also be generated. Under high-temperature faults, the insulating paper will carbonize.

[0064] Free gas was collected in a tube furnace and analyzed by gas chromatography. The results are as follows: Figure 13 As shown in the figure, C2H2 begins to appear at 600℃; the other six characteristic gases begin to rise at 400℃, with H2 content increasing sharply after 600℃; CH4, as the main characteristic gas of overheating faults, has a high content, while the contents of C2H4 and C2H6 are approximately the same.

[0065] Corresponding relationship between the overheating gas production characteristics of cottonseed oil and temperature range: Within the low-temperature superheating range of 90–300℃, cottonseed oil produces only six gases: H2, CH4, C2H4, C2H6, CO, and CO2, but not C2H2. C2H6 accounts for over 90% of the hydrocarbons, and the CO2 content is 15–20 times the total hydrocarbon content. Dissolved gases account for 78%–85% of the total gas production, while free gases account for 15%–22%. The total hydrocarbon content is typically below 500 μL / L. Within the medium-temperature superheating range of 300–700℃, cottonseed oil still primarily produces C2H6, maintaining a proportion above 50%, with a higher total gas production than in the low-temperature range. C2H2 begins to appear at 600℃. The CO and CO2 content in the oil-paper system is 1.5 times that of the pure oil system. The proportion of dissolved gas decreases slightly, while the proportion of free gas increases to 20%-25%, and the total hydrocarbon content is between 500-2000 μL / L. In the high-temperature superheating range of 700-800℃, the C2H2 concentration increases rapidly, reaching 77.39 ppm in the oil-paper system. The H2 content increases significantly, while the proportion of C2H6 decreases slightly but remains the main hydrocarbon gas. The proportion of free gas further increases to 25%-30%, and the total hydrocarbon content is higher than 2000 μL / L. Cottonseed oil has better thermal stability than mineral oil, and it only completely vaporizes at 600℃.

[0066] This invention realistically reproduces the entire process of long-term low-temperature overheating and instantaneous high-temperature overheating in transformers through temperature-zone heating. Standardized sample preparation eliminates raw material differences, and an oxygen-free atmosphere ensures that the generated gas originates solely from the thermal decomposition of oil. Dual-channel acquisition is used to fully capture all dissolved and free fault characteristic gases. Furthermore, through feature extraction and pattern modeling, a quantitative correspondence is established between cottonseed oil type, temperature range, gas generation characteristics, and fault type. This solution not only enables experimental simulation of overheating faults but also directly outputs characteristic parameters, graphical criteria, and comprehensive judgment rules that can be used for on-site DGA diagnosis, solving the problem that existing technologies cannot provide accurate fault diagnosis basis for cottonseed oil transformers.

[0067] Compared with the prior art, the present invention has the following beneficial effects: 1. The simulation design features differentiated temperature zones ranging from 90℃ to 800℃. The low-temperature zone (90-150℃) utilizes a constant-temperature chamber for overall heating and 192 hours of heat preservation. The medium-high temperature zone (200-800℃) employs a tubular furnace for point heating and gradient heat preservation time (1.5 min-2 h). The temperature and heat preservation time parameters closely match the actual fault conditions of transformers. This solves the technical problems of incomplete temperature zone coverage and unrealistic operation reproduction in existing technologies; it achieves accurate simulation of overheating faults across the entire temperature range, reproducing long-term overheating at low temperatures and localized instantaneous overheating at medium and high temperatures, improving simulation realism by over 40%.

[0068] 2. Standardized sample preparation process, including a uniform oil-to-paper weight ratio (15:1), pretreatment parameters for insulating oil and paper (oil dried at 100℃ for 24 hours under vacuum, paper dried at 110℃ for 12 hours), and vacuum impregnation parameters (-0.09MPa for 12 hours), and the process is compatible with both mineral oil and vegetable insulating oil. This solves the technical problems of limited compatibility and lack of standardized sample treatment in existing technologies; it achieves universal compatibility for two types of insulating oil, eliminates the influence of differences in raw material pretreatment on experimental results, and ensures that the relative standard deviation of experimental data for different oil samples and batches is ≤5%, significantly improving comparability.

[0069] 3. A tube furnace and a nitrogen-oxygen-free atmosphere protection system were employed to define the nitrogen purging parameters (80 mL / min × 20 min) and the micro-positive pressure maintenance parameters (5 mL / min), thus constructing an oxygen-free experimental environment. This addresses the technical problem in existing technologies where insulating oil is prone to oxidation and gas generation during high-temperature simulations, leading to significant interference with experimental results. It ensures that the detected gases are all products of thermal decomposition of insulating oil, avoiding oxidation interference and improving the accuracy of experimental results by more than 35%.

[0070] 4. A dual-path acquisition system for dissolved and free gases is adopted, collecting dissolved gases through reagent bottles and free gases through a sampling port at the top of the gas path, with simultaneous quantitative detection. This solves the technical problem of incomplete gas generation information acquisition in existing technologies; it completely captures all gas components generated by overheating faults, avoiding misjudgments of gas generation patterns due to missing free gases, and providing comprehensive data support for DGA diagnosis.

[0071] 5. Standardize the entire process, covering parameters and operational requirements for each step, from sample preparation, apparatus setup, atmosphere control, heating simulation, gas collection, and detection and analysis. This addresses the technical problem of poor reproducibility in existing technologies; ensures that experimental results can be reproduced by different researchers and laboratories, and enhances the engineering application value and scalability of the technical solution.

[0072] 6. Establish the correspondence between cottonseed oil, overheating fault temperature range and gas generation characteristic parameters, and form a special characteristic gas criterion and diagnostic method, which can be directly used to judge the type and severity of overheating faults in cottonseed oil transformers.

[0073] The steps of the various methods described above are only for clarity. In practice, they can be combined into one step or some steps can be split into multiple steps. As long as they include the same logical relationship, they are all within the protection scope of this invention. Adding insignificant modifications or introducing insignificant designs to the algorithm or process, without changing the core design of the algorithm and process, are also within the protection scope of this invention.

[0074] Another embodiment of the present invention relates to a computer device, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the cottonseed insulating oil transformer fault diagnosis method of the above embodiments.

[0075] The memory and processor are connected via a bus, which can include any number of interconnecting buses and bridges, connecting various circuits of one or more processors and memories. The bus can also connect various other circuits, such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and will not be described further herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be a single element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices over a transmission medium. Data processed by the processor is transmitted over the wireless medium via an antenna, which further receives data and transmits it to the processor.

[0076] The processor manages the bus and general processing, and also provides various functions, including timing, peripheral interfaces, voltage regulation, power management, and other control functions. Memory is used to store data used by the processor during operation.

[0077] Another embodiment of the present invention relates to a computer-readable storage medium storing a computer program. When executed by a processor, the computer program implements the method embodiments described above.

[0078] That is, those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0079] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A fault diagnosis method for cottonseed oil-insulating transformers, characterized in that, include: The contents of dissolved and free gases in the gases produced by the thermal cracking of cottonseed insulating oil in transformers were obtained, and the total hydrocarbon content, the content of each characteristic gas, and the content ratio between each characteristic gas were extracted from the dissolved and free gases. Based on the gas production pattern of cottonseed insulating oil in different temperature ranges, the boundaries of the regions corresponding to different fault types in the Duval triangle are adjusted, and the content ratios between each characteristic gas are projected onto the regions corresponding to different fault types in the adjusted Duval triangle to determine the fault type of the transformer. The temperature range of the transformer is determined based on the content ratio of each characteristic gas. Whether the transformer is involved in the deterioration of the oil-paper composite insulation is determined based on the content of each characteristic gas in the dissolved gas and free gas. The degree of transformer failure is determined based on the total hydrocarbon content and gas production rate in the dissolved gas and free gas. By combining the transformer's fault type, the temperature range corresponding to the fault type, whether the transformer involves deterioration of the oil-paper composite insulation, and the degree of transformer fault, the fault diagnosis results of the transformer are obtained.

2. The method for fault diagnosis of cottonseed insulating oil transformers according to claim 1, characterized in that, The extraction of total hydrocarbon content, content of each characteristic gas, and content ratio between each characteristic gas from dissolved and free gases includes: The sum of CH4, C2H4, C2H6, and C2H2 in the dissolved and free gases is extracted as the total hydrocarbon content. The contents of CH4, C2H4, C2H6, C2H2, CO, and CO2 in the dissolved and free gases are extracted separately. The ratios of C2H6 / C2H4, C2H2 / C2H4, CH4 / C2H6, CO2 / total hydrocarbon content, and CO / CO2 are calculated as the content ratios between each characteristic gas.

3. The method for fault diagnosis of cottonseed insulating oil transformers according to claim 1, characterized in that, The Duval triangle includes five regions: low-temperature overheating zone, medium-temperature overheating zone, high-temperature overheating zone, low-energy discharge zone, and high-energy discharge zone, corresponding to five fault types: low-temperature overheating fault, medium-temperature overheating fault, high-temperature overheating fault, low-energy discharge fault, and high-energy discharge fault. The adjustment of the boundaries of the regions corresponding to different fault types in the Duval triangle based on the gas generation patterns of cottonseed insulating oil in different temperature ranges includes: Based on the gas generation pattern of cottonseed insulating oil in different temperature ranges, the boundary line between the low-temperature overheating zone and the medium-temperature overheating zone is shifted 22% downwards towards the bottom of the Duval triangle, the boundary line between the medium-temperature overheating zone and the high-temperature overheating zone is shifted 12% downwards towards the bottom of the Duval triangle, and the boundary line between the low-energy discharge zone and the high-energy discharge zone is shifted 3% to the right of the Duval triangle.

4. The method for fault diagnosis of cottonseed insulating oil transformers according to claim 2, characterized in that, The process involves determining the transformer's temperature range based on the content ratios of various characteristic gases, determining whether the transformer is affected by deterioration of the oil-paper composite insulation based on the content of each characteristic gas in the dissolved and free gases, and determining the degree of transformer failure based on the total hydrocarbon content and gas production rate in the dissolved and free gases. If C2H6 / C2H4>10, C2H2 / C2H4=0, and CH4 / C2H6<0.1, then the transformer's temperature range is 90~300℃, corresponding to a low-temperature overheating fault; if 1 <c2h6 c2h4>10, 0 <C2H2 / C2H4<1、CH4 / C2H6> If the ratio is 0.1, the transformer temperature range is 300~700℃, corresponding to a medium-temperature overheating fault; if C2H6 / C2H4<1, C2H2 / C2H4>1, CH4 / C2H6>1, the transformer temperature range is 700-800℃, corresponding to a high-temperature overheating fault.< / c2h6> If the CO and CO2 content in the dissolved and free gases reaches 1.5 times or more of the total gas content produced by cottonseed insulating oil in the same temperature range, the oil-paper composite insulation of the transformer is judged to be deteriorated. If the total hydrocarbon content per liter of gas produced in the cottonseed insulating oil is <500 μL, and the daily increase in gas content per liter of gas is <10 μL, the transformer is determined to have a minor fault; if the total hydrocarbon content per liter of gas produced in the cottonseed insulating oil is 500-2000 μL, and the daily increase in gas content per liter of gas is 10-50 μL, the transformer is determined to have a moderate fault; if the total hydrocarbon content per liter of gas produced in the cottonseed insulating oil is >2000 μL, and the daily increase in gas content per liter of gas is >50 μL, the transformer is determined to have a severe fault.

5. The method for fault diagnosis of cottonseed insulating oil transformers according to claim 4, characterized in that, The transformer fault diagnosis results are obtained by combining the transformer fault type, the temperature range corresponding to the fault type, whether the transformer involves deterioration of oil-paper composite insulation, and the degree of transformer fault, including: If the fault type, the fault corresponding to the temperature range, and the fault severity of the transformer are all the same, then the corresponding fault level and whether the transformer involves deterioration of the oil-paper composite insulation will be used as the fault diagnosis result of the transformer.

6. The method for fault diagnosis of cottonseed insulating oil transformers according to claim 5, characterized in that, The transformer fault diagnosis results are obtained by combining the transformer fault type, the temperature range corresponding to the fault type, whether the transformer involves deterioration of oil-paper composite insulation, and the degree of transformer fault, including: If the fault type, the fault corresponding to the temperature range, and the fault severity of the transformer are different, then the fault diagnosis result will be the higher fault level and whether the transformer involves deterioration of the oil-paper composite insulation.

7. The fault diagnosis method for cottonseed insulating oil transformers according to claim 1, characterized in that, The thermal decomposition of cottonseed insulating oil in the transformer was obtained by simulating the overheating fault of the transformer using a pre-constructed experimental system.

8. The method for fault diagnosis of cottonseed insulating oil transformers according to claim 7, characterized in that, The simulated temperature range of the experimental system includes a low temperature range of 90-150℃ and a medium-high temperature range of 200-800℃.

9. A computer device, characterized in that, include: At least one processor; And a memory communicatively connected to at least one processor; wherein the memory stores instructions executable by at least one processor, the instructions being executed by at least one processor to enable at least one processor to perform the cottonseed insulating oil transformer fault diagnosis method as described in any one of claims 1 to 8.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the method for diagnosing faults in cottonseed insulating oil transformers as described in any one of claims 1 to 8.

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