Method and system for evaluating compatibility of fluorocarbon liquid with transformer materials

Abstract

The application discloses a fluorocarbon liquid and transformer material compatibility evaluation method and system, which first completes fluorocarbon liquid and transformer material sample pretreatment and collects initial performance, synchronously builds three kinds of aging systems of fluorocarbon liquid-material composite, fluorocarbon liquid blank and material blank, and carries out thermal aging under unified environment; solid and fluorocarbon liquid net degradation responses are calculated respectively combined with blank sample data, a degradation factor is solved relying on a normalization scoring rule, a compatibility comprehensive evaluation index is obtained through double-weight operation to complete grading determination, and a failure one-vote veto criterion is set. The application has the advantages that: the thermal aging interference of the material and medium itself is eliminated, liquid-solid two-way coupling degradation quantitative characterization is realized, single material and multi-material coupling aging conditions are compatible, quantitative grading and equipment safety bottom line are considered, the problem that existing technologies cannot simulate the multi-material coexistence working condition of a transformer is solved, and the application is suitable for research and development screening and engineering safety verification of various fluorocarbon liquid transformer insulation materials.

Description

Technical Field

[0001] This invention belongs to the technical field of compatibility evaluation of liquid insulating media and electrical equipment materials, specifically relating to a method and system for evaluating the compatibility of fluorocarbon liquid with transformer materials. Background Technology

[0002] Liquid insulating media are the core insulation and heat exchange cooling carriers for oil-immersed transformers and special liquid-immersed electrical equipment. Traditional mineral insulating oils are inexpensive and have mature processing technology, and have been widely used in conventional power distribution and main power transformers. However, mineral oils have a low inherent flash point and easily produce flammable volatiles after combustion, posing significant fire safety hazards in high-fire-prevention and high-safety-level scenarios such as urban underground substations, rail transit traction transformers, offshore wind power transformers, and transformers built into high-rise buildings.

[0003] To address the fire resistance shortcomings of mineral oil, the industry has gradually developed new flame-retardant and non-flammable insulating liquids such as natural ester oils, synthetic ester oils, and fluorocarbon liquids. Among them, fluorocarbon liquids, with their outstanding advantages such as complete non-flammability, extremely strong chemical inertness, high dielectric strength, excellent low-temperature fluidity, and wide thermal stability window, have become the preferred insulating and cooling medium for high-safety special transformers. However, their molecular polarity, dissolution and extraction characteristics, and interfacial compatibility differ significantly from traditional mineral oils and ester oils. After dozens of types of solid materials inside the transformer are immersed in fluorocarbon liquid for a long time, bidirectional interactions will occur, which restricts its engineering implementation.

[0004] Transformers contain a variety of solid components, including insulating paper, aramid paper, epoxy resin, rubber seals, enameled insulation layers, structural adhesives, metal substrates, and silicon steel coatings. When fluorocarbon liquid is in long-term hot contact with these solid materials, two degradation pathways occur: First, the fluorocarbon liquid extracts plasticizers, low-molecular-weight additives, resin monomers, and lignin from the paper materials, causing swelling, shrinkage, weight loss, decreased mechanical strength, surface cracking and powdering, and insulation delamination failure in the solid samples. Second, the extracted organic matter, metal ions, and material aging products continuously dissolve into the fluorocarbon liquid, causing turbidity and precipitation, a sharp increase in acid value and dielectric loss, and a significant decrease in breakdown voltage and volume resistivity, directly damaging the liquid's insulation and heat transfer performance. These two types of degradation are coupled and occur simultaneously; severe degradation in either direction will shorten the transformer's insulation life and lead to equipment malfunctions.

[0005] Currently, the industry's compatibility evaluation system for insulating liquids and solids still has significant technical shortcomings. Existing standards and test methods are all one-way evaluation models, which cannot quantitatively characterize the degradation effect of liquid-solid bidirectional coupling. Specific deficiencies include: 1. The evaluation is based on a single object and lacks a two-way response logic: Existing conventional immersion compatibility tests only observe the changes in mass, size, and strength of solid materials after immersion, and only characterize the erosion and deterioration of solids by liquids, completely ignoring the key process of reverse contamination and deterioration of insulating liquids by solid precipitates; some liquid aging tests only test the electrical and physical-chemical indicators of liquids after thermal aging, without considering the catalytic acceleration effect of solid material leaching on liquid aging. The two types of tests are disconnected from each other, the evaluation conclusions are one-sided, and they cannot match the real operating conditions of liquid-solid coexistence inside transformers.

[0006] 2. Lack of a blank control group prevents the removal of inherent aging interference, resulting in low evaluation accuracy: Existing accelerated aging tests only use a single aging sample consisting of "liquid + material". The performance changes obtained include two interference factors: performance degradation caused by the thermal degradation of the fluorocarbon liquid at high temperatures, and mechanical deterioration caused by simple thermo-oxidative aging of the solid material without liquid contact. Existing methods cannot eliminate these two types of inherent aging interference, and the measured changes cannot truly reflect the net deterioration degree specific to the interaction between the fluorocarbon liquid and the material. The cross-sectional comparability of test results at different temperatures, durations, and materials is extremely poor, making it difficult to form a unified quantitative judgment standard.

[0007] 3. Lack of standardized quantitative evaluation models, relying solely on qualitative visual judgment, resulting in weak engineering guidance: Traditional evaluation methods mainly rely on visual observation of sample surface condition and simple comparison of mass change rate, lacking unified normalized scoring rules and quantitative comprehensive indices. There is no weighted fusion calculation model for multi-dimensional degradation indicators such as solid mass, volume, tensile strength, surface morphology, liquid breakdown voltage, dielectric loss, acid value, and viscosity. It can only qualitatively describe vague conclusions such as "slight swelling" and "liquid turbidity," and cannot conduct graded comparisons of different fluorocarbon liquids and different material combinations, making it difficult to support the quantitative engineering needs of material screening, fluorocarbon liquid formulation selection, and equipment insulation structure design.

[0008] 4. Lack of a multi-material coupling system, creating blind spots in safety screening: Existing tests mostly use single solid material immersion schemes, failing to simulate the coupled environment of multiple insulation, sealing, and metallic materials coexisting inside the transformer. When multiple materials coexist, precipitates from different materials can react synergistically, exacerbating liquid degradation, resulting in significant deviations between single-material test results and actual engineering conditions. Furthermore, existing methods lack rigid failure prevention criteria: even with relatively small overall changes, if fatal failure phenomena such as severe rubber swelling, insulation paper embrittlement and delamination, enameled insulation peeling, or a sudden drop in liquid breakdown voltage occur, existing systems will still give a pass / fail conclusion, indicating a significant loophole in equipment safety assessment.

[0009] Patent publication number CN113012769A discloses a compatibility evaluation method for natural esters and solid materials. This patent uses natural ester insulating oil in combination with various solid materials in transformers to conduct accelerated aging control tests. It relies on setting up two sets of samples—a blank natural ester oil sample and a blend of natural ester and solid materials—for simultaneous aging. By testing three liquid electrical parameters—dielectric loss, acid value, and breakdown voltage—and combining a graded weighted scoring equation, a single compatibility coefficient is calculated, classifying multiple compatibility levels. This method can quantitatively assess the degree of degradation of the electrical performance of natural ester insulating oil by solid material precipitates, making it suitable for screening vegetable oil-based distribution transformer insulation systems. However, it only completes a one-way compatibility evaluation from the single dimension of insulating liquid performance degradation, relying solely on changes in the liquid's own electrical indicators to determine compatibility. It cannot construct standardized quantitative indicators such as solid material swelling, weight loss, mechanical attenuation, and surface cracking and powdering to characterize the insulation failure risk caused by fluorocarbon liquid or natural ester dielectric erosion of solids. Summary of the Invention

[0010] The problem to be solved by this invention is how to set the material matching of fluorocarbon liquid transformers and the compatibility evaluation index of bidirectional aging between fluorocarbon liquid and various solid materials of transformers during the research and development.

[0011] The present invention solves the above-mentioned technical problems through the following technical means: A method for evaluating the compatibility of fluorocarbon liquid with transformer materials includes the following steps: First, the fluorocarbon liquid and transformer material to be evaluated were selected and pretreated to obtain the initial performance parameters of the fluorocarbon liquid and transformer material before aging. Secondly, three types of test systems were constructed: fluorocarbon liquid-material composite aging system, fluorocarbon liquid blank aging system, and material blank aging system. Furthermore, the aging temperature, time, and environmental conditions were standardized, and accelerated thermal aging tests were carried out simultaneously on the three types of test systems. Once again, the transformer material performance was tested after aging, and the net degradation response of the solid material was determined by combining the data from the blank aging system. Next, the performance of the fluorocarbon liquid was tested after aging, and the net degradation response of the fluorocarbon liquid was determined by combining the data of the blank aging system of the fluorocarbon liquid. Subsequently, the degradation factors of solid materials and fluorocarbon liquid performance were calculated separately. Finally, the compatibility comprehensive evaluation index is obtained by using a dual-weight coefficient calculation. ,in accordance with Complete the compatibility classification and determination.

[0012] This invention constructs a complete process of "sample pretreatment - simultaneous acceleration of three types of aging systems - bidirectional net degradation extraction - dual degradation factor calculation - comprehensive index grading". By setting up two blank control groups to eliminate interference from the medium and the material's own thermal aging, it achieves bidirectional coupled degradation synchronous quantification of fluorocarbon liquid erosion of solid and solid reverse contamination of liquid. This solves the defects of existing technologies that only provide one-way evaluation and distorted results. The evaluation logic is consistent with the actual liquid-solid coexistence operation condition of transformers.

[0013] Preferably, the transformer material includes at least one of the following: insulating paper, insulating paperboard, aramid paper, epoxy resin, sealing rubber, enameled wire insulation layer, insulating varnish, structural adhesive, copper, aluminum, silicon steel sheet coating, insulating pad, and composite insulating component.

[0014] It can fully match all components that come into contact with the medium inside the fluorocarbon liquid transformer, and can achieve a comprehensive evaluation of compatibility of single materials and any combination of materials, avoiding the omission of evaluation materials that may lead to misjudgment in engineering selection.

[0015] Preferably, the fluorocarbon liquid-material composite aging system includes a single-material aging system and a multi-material combination aging system; the multi-material combination aging system includes two or more different types of transformer materials being immersed in fluorocarbon liquid together, which is used to evaluate the coexistence and coupling compatibility of multiple materials.

[0016] By distinguishing between single-material and multi-material combination aging systems, a multi-material coexistence coupled evaluation mode is added to simulate the real working condition of multiple materials inside the transformer simultaneously precipitating and mutually catalyzing each other to accelerate deterioration. This makes up for the shortcomings of the existing single-material immersion test, which has a large deviation from engineering practice. The multi-material coupled evaluation conclusion has more engineering reference value.

[0017] Preferably, the net degradation response of the solid material includes at least one of the following: net change rate of mass, net change rate of volume, net change rate of size, net retention rate of mechanical properties, and surface morphology degradation level. For indicators such as mass, volume, and dimensions, where greater deviations indicate more severe deterioration, the formula for calculating the net change rate is as follows: ; For indicators where a lower mechanical property retention rate indicates more severe degradation, the net degradation rate is calculated using the following formula: In the formula, For the first Net change rate or net decrease rate of the solid indicators; For solid materials before aging The initial values ​​of each indicator; For the first solid aging of the composite aging system Individual indicator values; For the first solid material in the blank system after aging Individual indicator values.

[0018] Dedicated net change rate calculation models were constructed for dimensional and mechanical solid indicators, respectively. These models accurately isolate the performance fluctuations caused by the material's own thermal aging when it is not in contact with fluorocarbon liquid, and retain only the true degradation range caused by the interaction between fluorocarbon liquid and material. The quantification accuracy is greatly improved, providing accurate basic data for subsequent degradation factor calculation.

[0019] Preferably, the weighted calculation formula for the degradation factor of the solid material is as follows: Among them, satisfying ; In the formula, It is a degradation factor for solid materials. The quantity of solid degradation indicators. For the first Weighting coefficients for solid indicators For solids Normalized degradation score for each indicator For the first The allowable variation limit for each solid material indicator.

[0020] A deterioration factor calculation model based on normalized scoring of solid indicators plus weighted summation is established. By unifying the evaluation scale of indicators with different physical dimensions through limit constraints, and with customizable indicator weights, the influence ratio of each indicator can be flexibly adjusted according to the evaluation focus of different materials such as sealing and insulation. The quantitative results are objective and consistent, and can be compared horizontally with different samples.

[0021] Preferably, the net degradation response index of the fluorocarbon liquid includes at least one of the following: moisture content, acid value, dielectric loss factor, volume resistivity, relative permittivity, breakdown voltage, thermal conductivity, and density. For moisture, acid value, and media loss factor categories, the methods for calculating the net deterioration rate include:

[0022] For breakdown voltage and volume resistivity, the methods for calculating the net degradation rate of change include:

[0023] For properties such as density, relative permittivity, and thermal conductivity, the methods for calculating the net rate of change of degradation include: In the formula, For the first Net deterioration rate of individual fluorocarbon liquid indicators The first time before aging of fluorocarbon liquid The initial values ​​of each indicator, The first aging of fluorocarbon liquid in the fluorocarbon liquid-material composite aging system. Individual indicator values, The first aging stage of fluorocarbon liquid in the blank aging system. Individual indicator values.

[0024] Based on the degradation patterns of fluorocarbon liquid indicators, a net degradation calculation model is constructed in three categories. It takes into account the multi-dimensional performance changes in physicochemical, electrical, and thermal stability, comprehensively captures the characteristics of liquid insulation and cooling performance degradation caused by material leachates, and fully covers the core assessment dimensions of fluorocarbon liquid as a special insulation and cooling medium, with no missing evaluation dimensions.

[0025] Preferably, the weighted calculation formula for the performance degradation factor of the fluorocarbon liquid is as follows: Among them, satisfying , In the formula, For the first Normalized degradation scores for performance degradation indicators of fluorocarbon liquids; For the first Permissible variation limits for performance indicators of fluorocarbon liquids; For the first Net deterioration rate of performance indicators of fluorocarbon liquids; It is a factor that degrades the performance of fluorocarbon liquids; For the first Weighting coefficients for performance degradation indicators of fluorocarbon liquids; This refers to the number of indicators related to the performance degradation of fluorocarbon liquids.

[0026] By normalizing the parameters to eliminate differences in different dimensions such as viscosity and breakdown voltage, a unified liquid degradation factor is obtained through weighting. This allows for a direct quantification of the overall destructive effect of solid precipitates on the performance of fluorocarbon liquids. The degree of pollution and degradation of different fluorocarbon media and materials can be directly compared horizontally, and the quantification standard is unified.

[0027] Preferably, the compatibility comprehensive evaluation index The calculation formula is: In the formula, For solid degradation factor weights, The weight of the fluorocarbon liquid degradation factor. When performing compatibility grading, if the solid material exhibits cracking, pulverization, peeling, severe swelling, severe shrinkage, or obvious delamination, or if the fluorocarbon liquid exhibits turbidity, precipitation, delamination, a breakdown voltage drop exceeding a set threshold, or an increase in the dielectric loss factor exceeding a set threshold, no calculation is required. The value is directly determined as either risk-compatible or incompatible.

[0028] A comprehensive evaluation index with both liquid and solid weights is constructed, which can focus on material degradation or liquid degradation as needed. At the same time, a failure veto mechanism is added, ensuring that the comprehensive score cannot cover up fatal safety defects such as cracking and sudden breakdown. It takes into account both quantitative grading and equipment safety bottom line, avoids high scores from masking major insulation failure risks, and makes engineering screening safer.

[0029] Preferably, when using a multi-material combination aging system, the solid degradation factor corresponding to each type of material is first calculated separately. Then calculate the comprehensive solid degradation factor of multiple materials. : Finally, Substituting into the comprehensive index formula, we obtain the comprehensive compatibility index of the multi-material system: To complete the comprehensive compatibility determination under multi-material coexistence conditions; where, This represents the total number of material types. For the first The importance and weight of transformer-like materials in the overall machine, satisfying ; For the first Solid material degradation factor for similar materials.

[0030] It provides a multi-material weighted comprehensive evaluation model for the whole machine, which assigns weights according to the importance of each material in the transformer and outputs a comprehensive compatibility index at the whole machine level. This solves the problem that the evaluation of a single material cannot reflect the compatibility of multiple materials in the whole machine, and directly supports the integrated material selection evaluation of the transformer's whole machine insulation system.

[0031] This invention also discloses a compatibility evaluation system for fluorocarbon liquid and transformer materials, comprising: The performance acquisition module is used to select the fluorocarbon liquid and transformer material to be evaluated and complete the pretreatment, and obtain the initial performance parameters of the fluorocarbon liquid and transformer material before aging, respectively. The experimental setup module is used to build a fluorocarbon liquid-material composite aging system, a fluorocarbon liquid blank aging system, and a material blank aging system. The accelerated aging module is used to unify the aging temperature, time, and environmental conditions, and to conduct accelerated thermal aging tests on three types of test systems simultaneously. The solid material net degradation response module is used to test the performance of transformer materials after aging and determine the solid material net degradation response by combining the data from the blank aging system of the material. The liquid material net degradation response module is used to test the performance of fluorocarbon liquids after aging, and to determine the net degradation response of the fluorocarbon liquid by combining data from a blank aging system. The degradation factor calculation module is used to calculate the degradation factor of solid materials and the performance degradation factor of fluorocarbon liquids, respectively. The comprehensive judgment module is used to calculate the comprehensive compatibility evaluation index based on the degradation factor of the solid material and the performance degradation factor of the fluorocarbon liquid, and to classify and judge the compatibility between the fluorocarbon liquid and the transformer material accordingly; the program executed in each module is the same as the above-mentioned compatibility evaluation method between fluorocarbon liquid and transformer material.

[0032] The advantages of this invention are: (1) Two-way comparative aging system to achieve two-way coupled quantitative evaluation of degradation: This application simultaneously sets up three control groups: composite aging group, fluorocarbon liquid blank group, and material blank group. The performance fluctuations caused by the thermal aging of fluorocarbon liquid itself and the thermal aging of solid materials are deducted respectively. Only the net degradation amount of the two-way interaction between fluorocarbon liquid eroding solid and solid precipitates reversibly polluting liquid is retained. This overcomes the shortcomings of the existing technology that only evaluates one direction, the test results include background error, and the deviation from the actual transformer operating conditions is large. The accuracy of the evaluation data is significantly improved. (2) Hierarchical standardized quantitative calculation system: Differentiated net degradation calculation formulas are designed for two types of objects, solid materials and fluorocarbon liquids, respectively. The differences in different physical dimensions such as mass, breakdown voltage and viscosity are eliminated by normalization. Solid degradation factors are constructed separately. fluorocarbon liquid deterioration factors Then, a unified compatibility composite index is obtained by weighting. It is equipped with a four-level grading standard, which gets rid of the subjectivity of traditional visual qualitative judgment and can carry out objective horizontal quantitative comparison of different fluorocarbon liquids and different material combinations. (3) Balancing conventional classification with fatal failure veto: On the one hand, through comprehensive index The graded classification is completed to meet the needs of conventional material screening and comparison. On the other hand, a hard safety veto criterion is added. If fatal insulation defects such as material pulverization or sudden drop in liquid breakdown voltage occur, the material will be directly judged as unqualified without being constrained by the comprehensive score. This avoids the high comprehensive score from covering up major equipment safety hazards and is more in line with the safety screening requirements of transformer engineering. (4) Supports dual modes of single material and multi-material coupling: distinguishes between two test schemes: single material aging and multi-material coexistence coupled aging; under multi-material working conditions, the comprehensive deterioration index is calculated by weighting the importance of each component to the whole machine, simulating the real operating environment of multiple insulation, sealing and metal materials coexisting and precipitates mutually catalyzing and accelerating deterioration inside the transformer. It can accurately verify the adaptation of a single material, and can also directly complete the comprehensive compatibility evaluation of the whole machine insulation system, making it more adaptable to engineering. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall process of a method for evaluating the compatibility of fluorocarbon liquid with transformer materials according to Embodiment 1 of the present invention; Figure 2This is a schematic diagram illustrating the setup of the fluorocarbon liquid-material composite aging system, the fluorocarbon liquid blank aging system, and the material blank aging system in an embodiment of the present invention for evaluating the compatibility of fluorocarbon liquid with transformer materials. Figure 3 This is a schematic diagram illustrating the calculation process of the solid material degradation factor, fluorocarbon liquid performance degradation factor, and comprehensive compatibility evaluation index in a method for evaluating the compatibility of fluorocarbon liquid and transformer materials according to Embodiment 1 of the present invention. Figure 4 This is a schematic diagram of the compatibility grading and veto determination process of a method for evaluating the compatibility of fluorocarbon liquid and transformer materials according to Embodiment 1 of the present invention. Figure 5 This is a surface morphology degradation scoring rule table for a method for evaluating the compatibility of fluorocarbon liquid with transformer materials according to Embodiment 1 of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1: See Figure 1 The compatibility evaluation method for fluorocarbon liquid and transformer material of the present invention includes the following steps: S1, selecting the fluorocarbon liquid to be evaluated and the transformer material, pretreating the transformer material, and obtaining the initial performance parameters of the fluorocarbon liquid and the transformer material before aging; S2, immersing the transformer material in the fluorocarbon liquid to construct a fluorocarbon liquid-material composite aging system, and setting up a fluorocarbon liquid blank aging system and a material blank aging system respectively; S3, under the set aging conditions, conducting accelerated thermal aging tests on the fluorocarbon liquid-material composite aging system, the fluorocarbon liquid blank aging system, and the material blank aging system. S4. Obtain the performance parameters of the transformer material after aging, and determine the net degradation response of the solid material by combining the test results of the blank aging system of the material; S5. Obtain the performance parameters of the fluorocarbon liquid after aging, and determine the net degradation response of the fluorocarbon liquid by combining the test results of the blank aging system of the fluorocarbon liquid; S6. Calculate the degradation factor of the solid material and the performance degradation factor of the fluorocarbon liquid according to the net degradation response of the solid material and the net degradation response of the fluorocarbon liquid; S7. Calculate the comprehensive compatibility evaluation index according to the degradation factor of the solid material and the performance degradation factor of the fluorocarbon liquid, and classify the compatibility between the fluorocarbon liquid and the transformer material accordingly.

[0036] In this embodiment, a fluorocarbon liquid to be evaluated and a cellulose insulating paper for transformers are selected as the evaluation objects.

[0037] The specific process is as follows: S1. Select the fluorocarbon liquid to be evaluated and the transformer material, pretreat the transformer material, and obtain the initial performance parameters of the fluorocarbon liquid and the transformer material before aging.

[0038] The specific process of step S1 includes: 1. Sample cutting and sorting See Figure 2 Select brand-new cellulose insulating paper that is undamaged, free of holes, free of stains, and free of moisture. Cut the insulating paper into samples of uniform size. In this embodiment, 6 insulating paper samples are prepared in the same batch. 3 samples are used for the fluorocarbon liquid-insulating paper composite aging system, and 3 samples are used for the material blank aging system. The edges of all samples are polished smooth to avoid burrs interfering with immersion and mechanical testing. All samples are uniquely numbered, with composite group numbered P1~P3 and blank group numbered K1~K3 (the specific number of samples is adjusted according to actual needs).

[0039] 2. Pre-treatment of insulating paper by drying and dehumidification Cellulose insulating paper is highly hygroscopic, and moisture can interfere with the aging and degradation test results. All cut insulating paper samples are placed in a vacuum drying oven, with a drying temperature of 105℃ and a vacuum degree ≤500Pa, and dried at this constant temperature for 24 hours (specific drying conditions can be adjusted according to actual conditions). After drying, the samples are not removed; the vacuum drying oven is allowed to cool naturally to room temperature, and then transferred to a constant temperature and humidity sealed equilibrium chamber for 48 hours (this can be adjusted as needed) to achieve moisture equilibrium and eliminate initial performance deviations caused by differences in sample moisture content.

[0040] 3. Fluorocarbon liquid pretreatment Take a sufficient amount of the fluorocarbon liquid to be evaluated, filter it to remove trace impurities and particulate matter; seal the filtered fluorocarbon liquid and place it in a dry and light-proof environment for 24 hours (adjust as needed) to eliminate tiny air bubbles inside the liquid and avoid the air bubbles affecting the aging process and electrical performance testing; divide it into two equal parts, one for the composite aging system and the other for the fluorocarbon liquid blank aging system.

[0041] 4. Collect all initial performance parameters of cellulose insulating paper before aging. The original performance tests were carried out on the insulating papers numbered P1~P3 and K1~K3 in sequence. The average value of 3 samples was taken as the initial reference value for each index: (1) Basic dimensions and mass: The initial mass of a single sample was measured using an electronic balance with an accuracy of 0.01 mg. The length, width, and thickness of the sample were measured using a digital caliper with an accuracy of 0.01 mm, and the initial volume was calculated. Record the initial length, width, and thickness dimensions of each sample. (2) Mechanical properties: The tensile strength and elongation at break of the specimens were tested according to the standard for tensile testing of electrical insulating paper, and the initial mechanical property values ​​were recorded. ; (3) Surface morphology: The surface state of the insulating paper fiber was observed using an optical microscope, and the initial surface state level was recorded as level 0 (no discoloration, no cracking, no fiber shedding).

[0042] 5. Collect all initial performance parameters of the fluorocarbon liquid before aging. Take the pretreated pure fluorocarbon liquid and test its complete set of initial physicochemical, electrical, and thermal properties under standard test conditions to serve as the initial reference values ​​for the liquid. Visually, the product is clear and free of impurities. Density and kinematic viscosity are tested using a dedicated viscosity-density tester. Trace moisture content is determined using a moisture analyzer. Acid value is detected using potentiometric titration. Dielectric loss factor, volume resistivity, and breakdown voltage are measured using a complete set of electrical testing equipment for insulating oil. Initial thermal conductivity and flash point data of the fluorocarbon liquid are recorded simultaneously.

[0043] 6. Data archiving All initial test values, sample numbers, pretreatment conditions, and ambient temperature and humidity of the insulating paper and fluorocarbon liquid were uniformly entered into the test log to form a complete initial performance parameter file, which served as the benchmark data for subsequent calculation of net degradation response.

[0044] S2. Immerse the transformer material in the fluorocarbon liquid to construct a fluorocarbon liquid-material composite aging system, and set up a fluorocarbon liquid blank aging system and a material blank aging system respectively.

[0045] The specific process of step S2 includes: 1. Establish a fluorocarbon liquid-material composite aging system A high-temperature resistant, sealed stainless steel aging container was selected. The inner wall of the container was pre-cleaned with anhydrous ethanol, dried, and cooled to room temperature to ensure no oil, impurities, or moisture residue remained inside. Then, the pre-treated fluorocarbon liquid to be evaluated was poured into the container, leaving sufficient space for expansion to prevent overflow at high temperatures. Next, three cellulose insulating paper samples (P1, P2, and P3) were completely immersed in the fluorocarbon liquid, separated from each other, without stacking or adhering to the container wall, ensuring full contact between the fluorocarbon liquid and the entire surface of the paper. Finally, the container's sealing cap was tightened, completing the fluorocarbon liquid-cellulose insulating paper composite aging system. This system is used to simultaneously simulate the two-way process of fluorocarbon liquid eroding the insulating paper and the paper leaching impurities that contaminate the fluorocarbon liquid.

[0046] 2. Establish a blank aging system for fluorocarbon liquid. A sealed stainless steel aging container of the same specifications and material as the one described above was selected and subjected to the same cleaning and drying pretreatment. Then, the same batch and volume of pretreated fluorocarbon liquid were poured into the container, without any cellulose insulating paper or other solid samples. Finally, the sealing cap was tightened to obtain a pure fluorocarbon liquid blank aging system. This system serves to characterize the performance degradation caused by the fluorocarbon liquid's own thermal aging at a set temperature and time; subsequent calculations will exclude interference from the liquid's background degradation.

[0047] 3. Establish a blank aging system for materials Select a sealed stainless steel aging container with identical specifications, material, and pretreatment process (the aging container can be a sealed container, an inert atmosphere container, an oxygen-controlled container, or a sealed container with a metal catalyst, depending on actual needs); then, without adding any fluorocarbon liquid, place only three cellulose insulating paper samples numbered K1, K2, and K3 inside the container, with the sample spacing and placement method completely consistent with the paper in the composite system; finally, tighten the sealing cap to obtain the blank aging system of the insulating paper; this system is used to characterize the dimensional, mechanical, and surface changes of the insulating paper caused by thermal aging without contact with fluorocarbon liquid, and can subsequently peel off the background degradation of the material's own thermal aging.

[0048] 4. System establishment and unified verification requirements After the three types of aging containers are sealed, their sealing performance is checked to ensure that there is no gas leakage. The container numbers, internal filling materials, sample numbers, and fluorocarbon liquid filling amounts of the three sets are recorded. Test logs are established to correspond one-to-one with the three aging systems to ensure that the subsequent aging, sampling, and testing processes are traceable.

[0049] S3. Under the set aging conditions, accelerated thermal aging tests are conducted on the fluorocarbon liquid-material composite aging system, the fluorocarbon liquid blank aging system, and the material blank aging system.

[0050] The specific process of step S3 includes: 1. Pretreatment and parameter setting of aging equipment A sealed aging oven with constant temperature hot air circulation is selected. It is preheated 24 hours in advance to stabilize the oven temperature to the aging temperature of 130℃ set in this embodiment (the aging temperature is preferably 80℃ to 180℃, and more preferably 100℃ to 160℃, depending on the specific needs). The oven is equipped with multiple layers of uniformly placed racks to ensure that the temperature difference between each area is ≤±1℃, which meets the temperature control accuracy requirements for accelerated thermal aging. The oven is filled with conventional air atmosphere without additional inert gas filling, which is consistent with the normal operating environment of power distribution transformers. The total aging time is set to 336 hours (the aging time is preferably 24 hours to 2000 hours, and more preferably 72 hours to 1000 hours, depending on the specific needs).

[0051] 2. All three types of aging containers should be placed together. Three sets of sealed stainless steel aging containers were placed synchronously and stably on the same shelf in the middle layer of the oven, with a gap of more than 2cm between the containers to ensure that the hot air of the oven could circulate evenly around each container. The three sets of containers were placed at the same height, with the same spacing and orientation to avoid uneven local temperature that could lead to differences in the degree of aging. All containers were placed vertically with the sealed caps facing upwards, without being placed on their sides or upside down, to prevent internal liquid leakage and local exposure of the samples.

[0052] 3. Synchronous constant temperature aging control throughout the entire process Once the oven reaches a stable temperature of 130℃, timing begins. The three containers simultaneously enter the aging cycle and run continuously for 336 hours without opening the oven door or removing any containers during the process, thus preventing sudden temperature changes and large influx of oxygen that could interfere with the aging reaction. The oven is equipped with an automatic timing and temperature recording device that automatically collects and stores the real-time temperature inside the oven every 2 hours. If the temperature deviates from the 130℃±1℃ range, the oven automatically raises or lowers the temperature to correct the deviation. Temperature operation records are maintained throughout the process to ensure that the thermal aging environment of the three systems is completely identical.

[0053] 4. Cooling operation at the end of the aging cycle After the 336-hour aging period is completed, turn off the oven heating system and allow it to cool naturally in hot air circulation mode. Do not spray with cold water or open the windows for sudden cooling. After cooling, remove the container and place it on a dust-free room temperature test bench to allow the internal temperature of the container to balance with the laboratory environment temperature before proceeding with subsequent sampling and testing operations.

[0054] 5. Aging process record archiving Complete records of all test information, including aging start and end times, temperature curves throughout the process, oven operating status, container placement, and cooling time, are kept together with the records of steps S1 and S2 to ensure traceability of conditions throughout the aging process and provide a unified benchmark for subsequent net degradation response calculations.

[0055] S4. Obtain the performance parameters of the transformer material after aging, and determine the net degradation response of the solid material by combining the test results of the blank aging system of the material.

[0056] The specific process of step S4 includes: 1. Separation and cleaning of the two types of insulating paper samples Open the containers for the composite aging system and the blank aging system, and take out the P1~P3 composite group insulating paper samples and the K1~K3 blank group insulating paper samples, respectively. The composite group samples have fluorocarbon liquid adhering to their surfaces. Gently wipe both sides of the paper with anhydrous ethanol to remove residual fluorocarbon media. Control the force during wiping to avoid pulling or damaging the paper fibers. After wiping, place them on a cleanroom tray. The blank groups have no fluorocarbon liquid adhering to them; simply brush off any surface dust with a cleanroom brush.

[0057] 2. Uniform temperature and humidity equilibrium pretreatment of insulating paper All six insulating paper samples were simultaneously placed in a vacuum drying oven and dried using the same drying process as in step S1 to remove solvents, trace amounts of adsorbed media inside the paper, and moisture. After drying, the samples were cooled to room temperature in the oven and then transferred to a constant temperature and humidity equilibrium chamber under the same conditions as in step S1 and placed in a sealed container for 48 hours to allow the moisture content and dimensions of the samples to return to an equilibrium state consistent with the initial test in S1, ensuring that the test benchmarks before and after were consistent.

[0058] 3. After the aging insulation paper has undergone a complete set of performance tests and balancing, the mass, dimensions, volume, mechanical properties, and surface morphology of the composite group and blank group samples are tested using the same testing equipment and standards as in step S1. The arithmetic mean of the three samples in each group is taken as the corresponding index of the system. Mass, dimension, and volume testing: The mass of each sample after aging was determined using an electronic balance with an accuracy of 0.01 mg; the length, width, and thickness were measured using a 0.01 mm digital caliper, and the volume of each sample was calculated; the average parameters of the composite system were recorded. Average index of blank material system .

[0059] Mechanical property testing: Using the same tensile rate and clamping distance as in step S1, the tensile strength and elongation at break of the specimens were tested to obtain the average mechanical properties of the two systems.

[0060] Surface morphology grading and evaluation: The fiber surface, delamination, cracking, and discoloration were observed using an optical microscope. (See reference...) Figure 5 Based on the standard morphology scoring table, the morphology degradation scores for the composite group and the blank group are given respectively.

[0061] 4. Calculate the net degradation response of cellulose insulating paper solid material Retrieve the initial reference parameters of the insulating paper recorded in step S1 The composite system indicators obtained in this test Material blank system indicators Differentiate between indicator types and apply the corresponding formulas to calculate the net deterioration value of a single indicator: (1) For indicators of mass, volume, and size: calculate the net change rate, retaining only the size or weight changes caused by the interaction between the fluorocarbon liquid and the paper, and eliminating the background changes caused by the paper being heated alone. The formula for calculating the net change rate is: ; (2) For the mechanical properties of tensile strength and elongation at break: calculate the net decrease rate, and the formula for calculating the net decrease rate is:

[0062] In the formula, For the first Net change rate or net decrease rate of the solid indicators; For solid materials before aging The initial values ​​of each indicator; For the first solid aging of the composite aging system Individual indicator values; For the first solid material in the blank system after aging Each index value. If the material properties in the composite aging system are higher than those in the blank aging system, the net degradation response is recorded as 0. (3) For surface morphology, the difference in morphology scores between the composite group and the blank group is directly taken as the net morphology degradation response, denoted as .

[0063] The net change rate, net decrease rate, and morphological degradation difference corresponding to all indicators are summarized to form a complete solid material net degradation response dataset of cellulose insulating paper corresponding to the fluorocarbon liquid. This dataset is simultaneously entered into the test log and serves as the basis for subsequent calculation of solid degradation factors.

[0064] S5. Obtain the performance parameters of the aged fluorocarbon liquid and, in conjunction with the test results of the blank aging system of the fluorocarbon liquid, determine the net degradation response of the fluorocarbon liquid.

[0065] The specific process of step S5 includes: 1. Sampling and Degassing of Fluorocarbon Liquid Open the fluorocarbon liquid-insulating paper composite aging container and the pure fluorocarbon liquid blank aging container respectively, and use a clean and dry pipette to extract an equal amount of fluorocarbon liquid sample from the middle of the container. Two samples of the fluorocarbon liquid to be tested were placed into sealed transparent sampling bottles and left to stand at room temperature in the dark for 24 hours to eliminate the tiny bubbles dissolved and trapped during the high-temperature aging process, and to avoid the bubbles interfering with the testing of electrical and physicochemical properties such as dielectric loss, breakdown voltage, and viscosity. The fluorocarbon liquid sample of the composite system was marked as The blank system fluorocarbon liquid sample was marked as Simultaneously retrieve the initial performance parameters of the fluorocarbon liquid recorded in step S1. As a calculation benchmark.

[0066] 2. Complete performance testing of fluorocarbon liquid Using the same testing instruments, experimental environment, and national standard testing methods as in step S1, all target indicators of the two types of fluorocarbon liquid samples were simultaneously tested. Each group of samples was tested three times, and the average value was taken. The performance indicators of the fluorocarbon liquid were categorized into three types based on their direction of change: higher values ​​indicate worse performance, lower values ​​indicate worse performance, and greater deviations indicate worse performance. The test results for each indicator were recorded. Indicators showing higher values ​​indicate worse performance, including moisture content, acid value, and dielectric loss factor; indicators showing lower values ​​indicate worse performance, including breakdown voltage and volume resistivity; and indicators showing greater deviations from the initial value indicate worse performance, including density, relative permittivity, and thermal conductivity.

[0067] 3. Substitute the values ​​of each type into the formula to calculate the net deterioration rate of the fluorocarbon liquid.

[0068] Type 1: Calculation formulas for moisture content, acid value, and media loss factor (the higher the value, the worse the liquid performance): ; In the formula: For the first Net deterioration rate of individual fluorocarbon liquid indicators The first time before aging of fluorocarbon liquid The initial values ​​of each indicator, The first aging of fluorocarbon liquid in the fluorocarbon liquid-material composite aging system. Individual indicator values, The first aging stage of fluorocarbon liquid in the blank aging system. Each index value. This calculation formula represents the increase in index value after deducting the increase caused by the thermal aging of the fluorocarbon liquid itself, retaining only the increase caused by the leaching of insulating paper.

[0069] Type 2: Breakdown voltage and volume resistivity (the smaller the value, the worse the liquid properties) calculation formulas: ; This calculation formula indicates that if the liquid properties of the composite system are better than those of the blank system, and there is no degradation, the net degradation rate is recorded as 0; only the performance degradation caused by paper precipitates is calculated.

[0070] Type 3: Calculation formulas for density, relative permittivity, and thermal conductivity (performance deteriorates the further away from the initial value): ; This calculation formula represents the difference in deviation between the composite group, the blank group, and the initial value. It excludes interference from the thermal expansion or thermal deformation of the liquid itself and only counts the property shifts caused by the exudate from the insulating paper.

[0071] 4. Single-index normalized degradation score calculation: For each fluorocarbon liquid index, the industry allowable variation limit for that index is considered. Calculate the normalized degradation score Calculation formula: ; In the formula: For the first Normalized degradation scores for performance degradation indicators of fluorocarbon liquids; For the first Permissible variation limits for performance indicators of fluorocarbon liquids; For the first The net degradation rate of each fluorocarbon liquid performance index; if the calculated result exceeds 100 points, 100 points will be uniformly taken to represent complete degradation and failure.

[0072] 5. Archive of Fluorocarbon Liquid Net Deterioration Response Dataset Summarizing all indicators Net deterioration rate Normalize the scores to form a complete net degradation response dataset for the fluorocarbon liquid in this experiment; record the sampling records, raw test data, calculation process of each index formula, and final scores in the test log, which will be used in subsequent step S6 to calculate the performance degradation factor of the fluorocarbon liquid. The basic raw data.

[0073] S6. Based on the net degradation response of the solid material and the net degradation response of the fluorocarbon liquid, calculate the degradation factor of the solid material and the performance degradation factor of the fluorocarbon liquid respectively.

[0074] The specific process of step S6 includes: 1. Calculate the normalized degradation score for each index of cellulose insulating paper.

[0075] (1) See Figure 3 Retrieve the net change rate or net decrease rate of each indicator of the insulating paper obtained in step S4. And the corresponding allowable variation limits for the engineering indicators The solid normalized degradation scoring formula was used to calculate the degradation step by step:

[0076] In the formula: For solids Normalized degradation score for each indicator For the first Permissible variation limits for individual solid material properties; For the first The net change rate or net decrease rate of the solid indicator. When the calculated result is greater than 100, it is uniformly taken as 100 points, which means that the indicator has completely deteriorated and failed.

[0077] (2) The evaluation indicators for the insulating paper in this embodiment include mass, volume, thickness, tensile strength, and surface morphology. 2. Calculate the degradation factor of solid materials

[0078] (1) In this embodiment, the mechanical and dimensional stability of insulating paper are the core evaluation focus, and the weight coefficients of each index are determined in advance by the analytic hierarchy process. All weights satisfy ; Substitute the weighted summation formula for solid degradation factors to calculate the total degradation factor. : In the formula It is a degradation factor for solid materials. The quantity of solid degradation indicators. For the first Weighting coefficients for solid indicators For solids The normalized degradation score of each indicator.

[0079] (2) The final solid degradation factor of the insulating paper in this experiment is obtained by multiplying the five scores of mass, volume, size, mechanical properties and surface morphology by their corresponding weights and summing them up. The recorded values ​​are archived. In this embodiment, the degradation indicators of solid materials include net mass change rate, net volume change rate, net dimensional change rate, net decrease rate of mechanical properties, and surface morphology degradation level. Therefore, specifically in this embodiment, In the formula These are the normalized degradation score for net change rate of mass, normalized degradation score for net change rate of volume, normalized degradation score for net change rate of size, normalized degradation score for net decrease rate of mechanical properties, and degradation score for surface morphology.

[0080] 3. Calculate the performance degradation factor of fluorocarbon liquid.

[0081] (1) Retrieve all fluorocarbon liquid indexes and normalize the degradation scores in step S5. To prioritize the electrical insulation performance of fluorocarbon liquids, an expert weighting method was used to determine the weights of each liquid indicator. The sum of weights satisfies Substitute the weighted calculation formula for the degradation factor of fluorocarbon liquid to solve. : In the formula: It is a factor that degrades the performance of fluorocarbon liquids; For the first Weighting coefficients for performance degradation indicators of fluorocarbon liquids; This refers to the number of indicators of performance degradation in fluorocarbon liquids. For the first Normalized degradation scores for performance degradation indicators of fluorocarbon liquids.

[0082] (2) Multiply the scores of all indicators such as moisture, acid value, dielectric loss, breakdown voltage, volume resistivity, density, and thermal conductivity by their respective weights and sum them to obtain the overall degradation factor of the fluorocarbon liquid. Specifically, in this embodiment, when the performance indicators of the fluorocarbon liquid include breakdown voltage, dielectric loss factor, volume resistivity, viscosity, moisture content, acid value, relative permittivity, and thermal stability, the performance degradation factor of the fluorocarbon liquid is calculated according to the following formula: In the formula, The normalized score is the net degradation score of the breakdown voltage. The normalized score for the net degradation of the dielectric loss factor. The normalized score is the net degradation score of volume resistivity. For the normalized score of net viscosity degradation, Normalized score for net moisture degradation. The normalized score for net acid value degradation. The normalized score is the net degradation of the relative permittivity. The score is the normalized score for the net degradation of thermal stability performance.

[0083] 4. Data organization and archiving Summarize the various indicators of solids separately Weight Calculation process and results; Organize the various indicators of fluorocarbon liquid separately. Weight Calculation process and results: All calculation data, weighting criteria, and limit standards for the two sets of degradation factors are entered into the test log and used as the basis for calculating the compatibility comprehensive evaluation index in step S7. Input parameters.

[0084] S7. Calculate the comprehensive compatibility evaluation index based on the degradation factor of the solid material and the degradation factor of the fluorocarbon liquid performance, and classify the compatibility between the fluorocarbon liquid and the transformer material accordingly.

[0085] The detailed process of step S7 includes: 1. Determine the weighting coefficients corresponding to solid and liquid degradation factors.

[0086] (1) When the performance of solid materials and fluorocarbon liquids is equally important, the preferred option is: ; (2) When the evaluation focuses on the impact of fluorocarbon liquid on sealing materials, polymer materials, or insulating materials, the preferred option is: ; (3) When the evaluation focuses on the impact of solid material precipitates on the insulation performance of fluorocarbon liquid, the preferred option is: .

[0087] This embodiment evaluates transformer cellulose insulation paper, focusing on the degree of corrosion and degradation caused by fluorocarbon liquid, with weights configured according to the optimal scheme. Solid degradation weights. fluorocarbon liquid degradation weight Satisfying the constraints The weight values ​​and reasons for selection in this experiment were recorded in the experiment log.

[0088] 2. Substitute into the formula to calculate the comprehensive compatibility evaluation index.

[0089] (1) See Figure 4 Extract the degradation factor of cellulose insulating paper obtained in step S6 fluorocarbon liquid deterioration factors The calculation is carried out using a comprehensive index formula: In the formula: For solid degradation factor weights, The weight of the fluorocarbon liquid degradation factor. ; It is a comprehensive compatibility evaluation index; It is a solid deterioration factor for cellulose insulating paper; It is a factor that degrades the performance of fluorocarbon liquids.

[0090] (2) Calculation logic: A higher value indicates more severe degradation, which is obtained by subtracting the weighted sum of degradation from 100. , A higher value indicates better compatibility between the two.

[0091] 3. Basic grading determination Comparison calculation results Preliminary numerical classification: Preliminary assessment indicates excellent compatibility; Preliminary assessment indicates acceptable compatibility; Preliminary assessment indicates risk compatibility; Preliminary assessment: Incompatible.

[0092] 4. Security review of veto items Verify the insulation paper observation records (S4) and fluorocarbon liquid test records (S5) to determine if any hard rejection conditions have been triggered. If either condition is met, the compatibility level will be directly downgraded, and the test will no longer be conducted. Preliminary classification results.

[0093] Verification of rejection scenarios for solid materials (for cellulose insulation paper): Check the surface morphology and mechanical test data of the aged insulation paper to see if there are any failure phenomena such as cracking, powdering, peeling, severe swelling, severe shrinkage, interlayer separation, or obvious embrittlement.

[0094] Verification of fluorocarbon liquid rejection conditions: Check the appearance and electrical properties of the fluorocarbon liquid after aging: whether there is turbidity, precipitation, or stratification; whether the breakdown voltage drops beyond the set threshold; whether the dielectric loss factor increases beyond the set threshold.

[0095] If any of the veto conditions are triggered: the risk is directly determined to be compatible or incompatible; if no veto occurs, then... The preliminary classification corresponding to the numerical values ​​serves as the formal compatibility level.

[0096] 5. Output the final compatibility evaluation conclusion between this fluorocarbon liquid and cellulose insulating paper. Summary of complete calculation data: weights Values, numerical value numerical value Calculation process Preliminary grading and veto of verification results; engineering reference suggestions based on the final compatibility rating: Excellent compatibility: This fluorocarbon liquid can be directly used with cellulose insulating paper for transformer insulation system design; Acceptable compatibility: Suitable for engineering use; long-term operation requires regular monitoring of insulation and liquid properties. Risk compatibility: Direct batch application is not recommended; the surface treatment of the insulating paper needs to be optimized or the aging verification cycle needs to be extended. Incompatibility: This fluorocarbon liquid must not be used in conjunction with cellulose insulating paper.

[0097] Integrate all test, calculation, and judgment data from S1 to S7 to form a complete fluorocarbon liquid-cellulose insulating paper compatibility evaluation test report.

[0098] Example 2: This embodiment is entirely consistent with the principle of Embodiment 1, the only difference being that the object of Embodiment 1 is insulating paper, while the object of this embodiment is sealing rubber. The main differences from the process of Embodiment 1 are twofold: firstly, the aging treatment; in this embodiment, the aging environment is set to 120°C for 500 hours. Secondly, the solid material degradation factor. The calculation. Since the evaluation of sealing rubber focuses on material swelling, liquid absorption, extraction, and volume stability, the solid material degradation factor... During the calculation, the weights of each item are adjusted as follows: The remaining steps are exactly the same as in Example 1.

[0099] Example 3: This embodiment is entirely consistent with the principles of Embodiments 1 and 2, the only difference being that Embodiments 1 and 2 focused on a single material, while this embodiment selects a combination of multiple transformer materials, including insulating paper, insulating cardboard, sealing rubber, epoxy resin, copper sheet, and enameled wire, as the materials to be evaluated. These materials were immersed together in a fluorocarbon solution according to a predetermined ratio to simulate the actual environment of multiple materials coexisting inside a transformer. Simultaneously, a fluorocarbon solution blank aging system and blank aging systems for each material were set up. All systems were aged at 150°C for 720 hours.

[0100] After aging, the mass, volume, dimensions, mechanical properties, and surface condition of each type of material were tested, as well as the physicochemical, electrical, thermal, and flammability properties of the fluorocarbon liquid. The solid material degradation factor was calculated for each type of material. ,in Indicates the first Type of material.

[0101] Comprehensive solid material degradation factor of multi-material combination system Calculate according to the following formula: In the formula This represents the total number of material types. For the first The importance and weight of transformer-like materials in the overall machine, satisfying ; For the first Solid material degradation factor for similar materials.

[0102] Then, based on the performance degradation factor of fluorocarbon liquid in the multi-material combination system... and comprehensive solid material degradation factors Calculate the comprehensive compatibility evaluation index : Finally, based on The overall compatibility of fluorocarbon liquid with various transformer material combination systems is classified and determined.

[0103] Example 4: The principle of this embodiment is completely consistent with that of the above embodiments. The main difference is that the above embodiments explore the compatibility of different transformer materials with fluorocarbon liquid, while this embodiment explores the compatibility of different fluorocarbon liquids.

[0104] Specifically, this embodiment selects three fluorocarbon liquids—A, B, and C—as the research objects, and evaluates their compatibility with insulating paper, sealing rubber, epoxy resin, and enameled wire using the method of this invention. A comprehensive compatibility evaluation index for each fluorocarbon liquid-material combination is obtained. The overall method is completely consistent with the above embodiments.

[0105] When a certain fluorocarbon liquid is combined with all key materials If all values ​​are greater than or equal to 75 and no veto criterion is triggered, the fluorocarbon liquid is deemed to have basic engineering compatibility.

[0106] When a certain fluorocarbon liquid reacts with any key material If the value is less than 60, or if there is severe swelling of the sealing rubber, obvious embrittlement of the insulating paper, peeling of the enameled wire insulation layer, obvious turbidity of the fluorocarbon liquid, or a significant decrease in breakdown voltage, it is determined that the fluorocarbon liquid is incompatible with the material combination and it is not recommended to use it directly in the corresponding transformer material system.

[0107] When a certain fluorocarbon liquid is in contact with key materials When the value is between 60 and 75, it is considered to be risk-compatible, and engineering applications need to be carried out after optimizing the material type, improving the surface treatment, adjusting the sealing material, or adding long-term aging verification.

[0108] Through the above methods, the present invention can provide a quantitative evaluation basis for the material selection, matching material screening and engineering application of fluorocarbon liquid in transformers.

[0109] In summary, the present invention has the following advantages: This application innovatively sets up three synchronous aging systems: composite, fluorocarbon liquid blank, and material blank. This allows for precise isolation of background interference caused by the thermal aging of the medium and the material itself. It simultaneously quantifies the bidirectional coupling effect of fluorocarbon liquid erosion of the solid and the reverse degradation of the liquid by solid precipitates, overcoming the shortcomings of existing technologies that only offer one-way evaluation and have large deviations in experimental data. Furthermore, it designs matching calculation rules for different types of performance indicators, unifies the evaluation scale of each physical quantity through normalization, and obtains a standardized comprehensive evaluation index by weighting the independent degradation factors of solid and liquid separately. This abandons the traditional visual qualitative judgment method, resulting in objective and unified evaluation results that can be compared horizontally with different samples. The scheme incorporates both gradient grading judgment and a fatal failure veto mechanism. While quantifying material selection comparisons, it avoids the concealment of major equipment safety hazards such as high comprehensive scores masking insulation cracking and sudden drops in liquid insulation performance. It is adaptable to both single-material verification and multi-material coexistence coupled aging conditions. It can be used for single-component adaptation screening as well as for integrated compatibility assessment of the entire transformer insulation system, comprehensively covering various application scenarios in the research and development, engineering selection, and safety verification of new fluorocarbon liquid transformers, significantly improving practicality and evaluation accuracy.

[0110] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Terms such as "upper," "lower," "left," "right," "front," and "rear" used in the invention are merely for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0111] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating the compatibility of fluorocarbon liquid with transformer materials, characterized in that, Includes the following steps: First, the fluorocarbon liquid and transformer material to be evaluated were selected and pretreated to obtain the initial performance parameters of the fluorocarbon liquid and transformer material before aging. Secondly, three types of test systems were constructed: fluorocarbon liquid-material composite aging system, fluorocarbon liquid blank aging system, and material blank aging system. Furthermore, the aging temperature, time, and environmental conditions were standardized, and accelerated thermal aging tests were carried out simultaneously on the three types of test systems. Once again, the transformer material performance was tested after aging, and the net degradation response of the solid material was determined by combining the data from the blank aging system. Next, the performance of the fluorocarbon liquid was tested after aging, and the net degradation response of the fluorocarbon liquid was determined by combining the data of the blank aging system of the fluorocarbon liquid. Subsequently, the degradation factors of solid materials and fluorocarbon liquid performance were calculated separately. Finally, the compatibility comprehensive evaluation index is obtained by using a dual-weight coefficient calculation. ,in accordance with Complete the compatibility classification and determination.

2. The method for evaluating the compatibility of fluorocarbon liquid with transformer materials according to claim 1, characterized in that, The transformer materials include at least one of the following: insulating paper, insulating paperboard, aramid paper, epoxy resin, sealing rubber, enameled wire insulation layer, insulating varnish, structural adhesive, copper, aluminum, silicon steel sheet coating, insulating pads, and composite insulating components.

3. The method for evaluating the compatibility of fluorocarbon liquid with transformer materials according to claim 1, characterized in that, The fluorocarbon liquid-material composite aging system includes a single-material aging system and a multi-material combination aging system; the multi-material combination aging system includes two or more different types of transformer materials being immersed in fluorocarbon liquid together, which is used to evaluate the coexistence and coupling compatibility of multiple materials.

4. The method for evaluating the compatibility of fluorocarbon liquid with transformer materials according to claim 1, characterized in that, The net degradation response of the solid material includes at least one of the following: net change rate of mass, net change rate of volume, net change rate of size, net retention rate of mechanical properties, and surface morphology degradation level. For indicators such as mass, volume, and dimensions, where greater deviations indicate more severe deterioration, the formula for calculating the net change rate is as follows: ； For indicators where a lower mechanical property retention rate indicates more severe degradation, the net degradation rate is calculated using the following formula: In the formula, For the first Net change rate or net decrease rate of the solid indicators; For solid materials before aging The initial values ​​of each indicator; For the first solid aging of the composite aging system Individual indicator values; For the first solid material in the blank system after aging Individual indicator values.

5. The method for evaluating the compatibility of fluorocarbon liquid with transformer materials according to claim 4, characterized in that, The weighted calculation formula for the degradation factor of the solid material is as follows: Among them, satisfying ; In the formula, It is a degradation factor for solid materials. The quantity of solid degradation indicators. For the first Weighting coefficients for solid indicators For solids Normalized degradation score for each indicator For the first The allowable variation limit for each solid material indicator.

6. The method for evaluating the compatibility of fluorocarbon liquid with transformer materials according to claim 5, characterized in that, The net degradation response index of the fluorocarbon liquid includes at least one of the following: moisture content, acid value, dielectric loss factor, volume resistivity, relative permittivity, breakdown voltage, thermal conductivity, and density. For moisture, acid value, and media loss factor categories, the methods for calculating the net deterioration rate include: For breakdown voltage and volume resistivity, the methods for calculating the net rate of change of degradation include: For properties such as density, relative permittivity, and thermal conductivity, the methods for calculating the net rate of change of degradation include: In the formula, For the first Net deterioration rate of individual fluorocarbon liquid indicators The first time before aging of fluorocarbon liquid The initial values ​​of each indicator, The first aging of fluorocarbon liquid in the fluorocarbon liquid-material composite aging system. Individual indicator values, The first aging stage of fluorocarbon liquid in the blank aging system. Individual indicator values.

7. The method for evaluating the compatibility of fluorocarbon liquid with transformer materials according to claim 6, characterized in that, The weighted calculation formula for the performance degradation factor of fluorocarbon liquid is as follows: Among them, satisfying , In the formula, For the first Normalized degradation scores for performance degradation indicators of fluorocarbon liquids; For the first Permissible variation limits for performance indicators of fluorocarbon liquids; For the first Net deterioration rate of performance indicators of fluorocarbon liquids; It is a factor that degrades the performance of fluorocarbon liquids; For the first Weighting coefficients for performance degradation indicators of fluorocarbon liquids; This refers to the number of indicators related to the performance degradation of fluorocarbon liquids.

8. The method for evaluating the compatibility of fluorocarbon liquid with transformer materials according to claim 7, characterized in that, The compatibility comprehensive evaluation index The calculation formula is: In the formula, For solid degradation factor weights, The weight of the fluorocarbon liquid degradation factor. , It is a comprehensive compatibility evaluation index; It is a solid degradation factor; This is a performance degradation factor for fluorocarbon liquids. When determining compatibility, if the solid material exhibits cracking, pulverization, peeling, severe swelling, severe shrinkage, or obvious stratification, or if the fluorocarbon liquid exhibits turbidity, precipitation, stratification, a breakdown voltage drop exceeding a set threshold, or an increase in the dielectric loss factor exceeding a set threshold, no calculation is required. The value is directly determined as either risk-compatible or incompatible.

9. The method for evaluating the compatibility of fluorocarbon liquid with transformer materials according to claim 8, characterized in that, When using a multi-material aging system, first calculate the solid degradation factor for each type of material separately. Then calculate the comprehensive solid degradation factor of multiple materials. : Finally, Substituting into the comprehensive index formula, we obtain the comprehensive compatibility index of the multi-material system: To complete the comprehensive compatibility determination under multi-material coexistence conditions; where, This represents the total number of material types. For the first The importance and weight of transformer-like materials in the overall machine, satisfying ; For the first Solid material degradation factor for similar materials.

10. A compatibility evaluation system for fluorocarbon liquid and transformer materials, characterized in that, include: The performance acquisition module is used to select the fluorocarbon liquid and transformer material to be evaluated and complete the pretreatment, and obtain the initial performance parameters of the fluorocarbon liquid and transformer material before aging, respectively. The experimental setup module is used to build a fluorocarbon liquid-material composite aging system, a fluorocarbon liquid blank aging system, and a material blank aging system. The accelerated aging module is used to unify the aging temperature, time, and environmental conditions, and to conduct accelerated thermal aging tests on three types of test systems simultaneously. The solid material net degradation response module is used to test the performance of transformer materials after aging and determine the solid material net degradation response by combining the data from the blank aging system of the material. The liquid material net degradation response module is used to test the performance of fluorocarbon liquids after aging, and to determine the net degradation response of the fluorocarbon liquid by combining data from a blank aging system. The degradation factor calculation module is used to calculate the degradation factor of solid materials and the performance degradation factor of fluorocarbon liquids, respectively. The comprehensive judgment module is used to calculate the comprehensive compatibility evaluation index based on the degradation factor of the solid material and the performance degradation factor of the fluorocarbon liquid, and to classify and judge the compatibility between the fluorocarbon liquid and the transformer material accordingly.

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