Synthetic ester and insulating paint compatibility evaluation method based on dynamic weighting

Abstract

The invention discloses a method for evaluating compatibility of synthetic ester and insulating paint based on dynamic weighting, and relates to the technical field of electrical insulation. According to the evaluation method, synthetic ester is taken as a blank oil sample, a blend of synthetic ester and insulating paint is taken as an experimental sample, dehydration and degassing pretreatment and aging experiment are respectively carried out, and then electrical and physical and chemical performance indexes are tested; the evolution rule of the performance of the synthetic ester and the insulating paint can be observed and analyzed from multiple dimensions and multiple angles, different weights are distributed based on the variation degree of each index under different aging time, the compatibility score of the synthetic ester and the insulating paint is determined, and the compatibility evaluation system table is referred to. Therefore, the compatibility of the synthetic ester and the insulating oil can be evaluated more objectively, reliably, quickly and accurately, guidance is provided for the synthetic ester before the synthetic ester is put into electrical equipment, the blank of a current method for testing the compatibility of the synthetic ester oil and the insulating paint is filled, and the method is of great significance to long-term stable operation of the electrical equipment.

Description

Technical Field

[0001] The invention relates to the technical field of electrical insulation, and in particular to a method for evaluating the compatibility of synthetic ester and insulating varnish based on dynamic weighting. Background Art

[0002] The normal operation of power equipment, especially electrical equipment such as transformers and capacitors, depends on an effective electrical insulation system, which usually includes insulating media and insulating materials. The insulating media is used to fill the gaps in equipment such as transformers to ensure electrical insulation performance, while dissipating heat and preventing corona discharge. Insulating materials are usually used as wrapping or impregnating materials for coils to prevent short circuits between conductors. Traditionally, mineral oil has been widely used as an insulating medium, but with the increasing requirements for biodegradability and people's increasing performance requirements, synthetic ester insulating oil has gradually become an alternative.

[0003] Synthetic ester oil is a liquid medium with excellent insulating properties. It has obvious advantages in biodegradability, high ignition point and excellent thermal stability. Therefore, it is widely used in power equipment that requires high safety and environmental protection. The outstanding performance of synthetic ester oil in practical applications makes it a good choice to replace traditional mineral oil, especially in occasions with high fire hazard requirements. However, although synthetic ester oil performs well in some aspects, its compatibility with insulating varnish (such as impregnating varnish for coil insulation) is still a topic worthy of in-depth study. Insulating varnish is usually used in the coil windings of transformer coils and other electrical equipment as an insulating layer material to protect the wire from environmental and electrical stress. Therefore, the compatibility between insulating oil and insulating varnish is crucial to ensure the long-term reliability of electrical equipment.

[0004] In traditional systems using mineral oil as insulating oil, the compatibility between insulating varnish and mineral oil is relatively good, and long-term industrial practice has proven their effectiveness in practical applications. However, the chemical structure of synthetic ester oil is significantly different from that of mineral oil, mainly because the presence of ester bonds makes synthetic ester oil have strong polarity and chemical activity. These differences may cause certain problems in the compatibility between synthetic ester oil and traditional insulating varnish, and may even cause the performance of insulating varnish to deteriorate. Therefore, before applying synthetic ester oil to electrical equipment, its compatibility with insulating varnish needs to be evaluated to ensure the long-term stability of the insulation system in a specific application.

[0005] In the existing test methods, although certain compatibility data can be provided, these methods often require a long test time, and the test conditions are difficult to fully simulate the complex working conditions in the actual operating environment. In addition, there is no specific test for the compatibility of synthetic esters and insulating varnishes and a method for quantifying the test indicators for comprehensive evaluation. Therefore, there is an urgent need for a simpler, faster and more reliable method to evaluate the compatibility of synthetic ester oils and insulating varnishes to meet the needs of modern electrical equipment design and manufacturing. Summary of the invention

[0006] The present invention provides a method for evaluating the compatibility of synthetic ester and insulating varnish based on dynamic weighting. By testing various electrical and physical and chemical properties of blank oil samples and experimental oil samples, the index change rate after aging is calculated based on a dynamic weighted comprehensive evaluation method, which can be used to evaluate the compatibility between synthetic ester oil and insulating varnish.

[0007] In order to solve the above technical problems, the present invention provides a method for evaluating the compatibility of synthetic ester and insulating varnish based on dynamic weighting, comprising the following steps:

[0008] Synthetic ester is used as a blank oil sample, and a mixture of synthetic ester and insulating varnish is used as an experimental oil sample. The blank oil sample and the experimental oil sample are pre-treated with dehydration and degassing, respectively, and the treated samples are placed in a container, and the container is placed in an experimental temperature environment for an aging test, and 1-3 cycles are set;

[0009] The blank oil samples and experimental oil samples after aging were taken out, and the electrical and physical and chemical performance indicators of the synthetic ester in the oil samples were tested respectively, and the performance indicators of the insulating paint were observed as auxiliary analysis;

[0010] According to the performance index data of synthetic ester in blank oil samples and experimental oil samples, the dynamic weighted comprehensive evaluation method is used to calculate the compatibility score of synthetic ester and insulating varnish, and the compatibility score evaluation table is referred to to evaluate the degree of compatibility excellence.

[0011] As a preferred solution, the dynamic weighted comprehensive evaluation method is to calculate the dynamic weight value of a certain performance index in a certain period according to the electrical and physical and chemical performance index data of the synthetic ester in the oil sample, and to weight the compatibility score of each index in each period according to the dynamic weight value of each index in each period and the index value change rate of each index in each period, and to accumulate the compatibility scores of all indexes in all periods, and to calculate the compatibility scores of all indexes in all periods, and to obtain the compatibility grade by referring to the compatibility score evaluation table;

[0012] The dynamic weight value is calculated according to the dynamic weighting function, which is selected as a slightly large normal distribution function, and its expression is:

[0013] Where i is a performance index of synthetic ester in the oil sample, k is the period of the oil sample in the aging experiment, and W ik is the dynamic weight value of index i in the kth cycle, x is the value of the experimental oil sample index i in the kth cycle, ɑ k is the value of blank oil sample index i in the kth cycle, σ k It can be selected according to the actual situation. If the rate of change in the first half of the cycle is greater than that in the second half of the cycle, then σ k The value is 0.3, otherwise it is 0.7;

[0014] According to the characteristics of the indicator data, when x is better than or equal to ɑ k When W ik is 0 when x is less than ɑ k hour,

[0015] When the value of the aged oil sample is lower (higher) than this value, k When the value is above (below) this threshold, the influence of this value on the judgment of compatibility is negligible, so the weight is 0. k When the threshold is set, the greater the rate of change between the kth period and the k-1th period, the greater the impact on compatibility, and therefore the higher the weight.

[0016] As a preferred solution, the aging test is divided into 3 cycles, and the compatibility score is weighted and calculated according to the dynamic weight value of each indicator in each cycle and the indicator value change rate of each indicator in each cycle. The dynamic weighted compatibility score expression of the i-th indicator in all cycles is: The dynamic weighted compatibility score expression of all indicators in all periods is: Among them, Δ ik is the change rate of the ith indicator in the kth period. The change rate in the kth period is: (value in the kth period - value in the k-1th period) / (value in the kth period), W ik is the dynamic weight value of the ith indicator in the kth period, and n is the number of test performance indicators.

[0017] As a preferred solution, the relationship between the Y value and the compatibility level in the compatibility evaluation table is as follows:

[0018] When 0≤Y<0.2, they are compatible and can be used together;

[0019] When 0.2≤Y<0.4, they are basically compatible, but there is a risk of incompatibility when they are matched in large quantities;

[0020] When 0.4≤Y<0.6, the compatibility is poor, and when a large number of combinations are used, the risk of incompatibility is high;

[0021] When 0.6≤Y≤1, they are extremely incompatible and cannot be used together.

[0022] As a preferred solution, every 1cm 2 Add 10-15mL of synthetic ester to the insulating paint mixture.

[0023] As a preferred solution, the dehydration and degassing pretreatment is to place the experimental oil sample and the blank oil sample in different vacuum drying equipment respectively, set the temperature to 60-100°C, set the air pressure to 40-60Pa, and set the time to 36-72h.

[0024] As a preferred solution, the temperature of the aging test is 120-150°C, and the total aging time is 168-504h.

[0025] As a preferred solution, a magnetic stirrer is installed during the aging test to ensure the fluidity of the oil during the test and simulate the flow of oil under actual operating conditions.

[0026] As a preferred embodiment, the performance index of the synthetic ester in the blank oil sample and the experimental oil sample is at least one of dielectric loss, relative dielectric constant, volume resistivity, acid value, kinematic viscosity, and water content; the performance index test of the insulating varnish is at least one of hardness, scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis.

[0027] As a preferred solution, the dielectric loss is the dielectric loss measured at 90° C., the kinematic viscosity is the kinematic viscosity measured at 40° C., and the hardness of the insulating varnish is the Vickers hardness.

[0028] As a preferred solution, the insulating varnish curing process is performed according to technical parameters provided by the manufacturer or determined by the insulating varnish itself.

[0029] As a preferred solution, the insulating varnish liquid is cured according to the curing process and then mixed with synthetic ester as an experimental oil sample. The curing process of the insulating varnish is to maintain the temperature at 140-150°C for 1-3 hours, and then increase the temperature to 165-175°C at a heating rate of 2-3°C / min and maintain it for 6-8 hours.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention uses synthetic ester as a blank oil sample, and a blend of synthetic ester and insulating paint as a test sample. The blank oil sample and the test sample are pre-treated with dehydration and degassing respectively, which ensures that the error caused by the difference in the sample itself can be minimized. After the aging experiment, the electrical and physical and chemical performance indicators are tested. According to the dynamic weighted comprehensive evaluation method, the evolution law of the performance of synthetic ester and insulating paint can be observed and analyzed from multiple dimensions and angles. Different weights are assigned based on the degree of variation of each indicator under different aging time, and the compatibility score of synthetic ester and insulating paint is determined. With reference to the compatibility evaluation system table, the compatibility can be evaluated more objectively, reliably and efficiently. At the same time, it can be used to evaluate the compatibility under high temperature and low temperature environments, which is very important for understanding the compatibility and performance changes of materials under high temperature or low temperature environments, and is used to determine whether there is a difference in the compatibility of materials with insulating oil under various temperature conditions.

[0032] 2. This application evaluation method uses a series of standardized test methods to quickly and accurately evaluate the compatibility of synthetic esters and insulating oils, providing reliable data support to guide the design and manufacture of electrical equipment, and providing guidance for synthetic esters before they are put into use in electrical equipment, filling the gap in the current compatibility test methods for synthetic ester oils and insulating varnishes, which is of great significance to the long-term stable operation of electrical equipment. It can also be adjusted according to specific application scenarios to better simulate the compatibility under actual use conditions and ensure the safety and stability of the insulation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 : is a schematic flow chart of a method for evaluating the compatibility of synthetic ester and insulating varnish based on dynamic weighting in an embodiment of the present invention;

[0034] Figure 2 : Schematic diagram of a tank body loaded with blank oil samples and experimental oil samples in an embodiment of the present invention;

[0035] Figure 3 : A schematic diagram of a flow chart of a compatibility calculation subprogram in a dynamic weighted comprehensive evaluation method according to an embodiment of the present invention;

[0036] Figure 4 : is a graph of a normal distribution function that is larger than the normal distribution function in an embodiment of the present invention;

[0037] Figure 5 : It is a statistical image of the kinematic viscosity of the synthetic ester of the blank oil sample and the experimental oil sample after aging for 0-504h in Example 1 of the present invention (Note: a-blank oil sample; b-experimental oil sample containing No. 1 insulating paint; c-experimental oil sample containing No. 2 insulating paint);

[0038] Figure 6: It is the SEM image of the insulating paint surface containing the insulating paint experimental oil sample No. 1 in Example 1 of the present invention after aging for 0-504h (Note: from left to right are the samples aged for 0h, 168h, 336h, and 504h);

[0039] Figure 7 : This is an SEM image of the insulating varnish surface containing No. 1 insulating varnish experimental oil sample aged for 0-504h in Example 1 of the present invention (Note: from left to right are samples aged for 0h, 168h, 336h, and 504h, respectively). DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Example 1

[0042] A method for evaluating the compatibility of synthetic esters with insulating varnishes based on dynamic weighting, such as Figure 1 As shown, the following steps are included:

[0043] Step 1: Curing the insulating paint liquid according to the conventional curing process.

[0044] In this embodiment, the curing process of the insulating paint may be to maintain the temperature at 145±5°C for 2 hours, and then increase the temperature to 170±5°C at a heating rate of 2.5°C / min and maintain the temperature for 7 hours.

[0045] In this embodiment, the insulating varnish is divided into a No. 1 insulating varnish whose main component is epoxy resin and a No. 2 insulating varnish whose main component is unsaturated polyester resin.

[0046] Step 2: Mix the cured insulating varnish with synthetic ester as the experimental oil sample. The ratio of the surface area of ​​the insulating varnish to the volume of the oil used conforms to the ratio in the actual operation of the electrical equipment. The blank oil sample and the experimental oil sample are pre-treated by dehydration and degassing.

[0047] Preferably, the amount of synthetic ester is determined based on the consistency of the surface area of ​​the insulating varnish and the volume ratio of the synthetic ester with that in the actual operation of the electrical equipment.

[0048] Preferably, the synthetic ester oil to be tested may be a common synthetic ester oil or a synthetic ester oil containing additives, and the additives may optimize the formula of the synthetic ester oil.

[0049] In this embodiment, the synthetic ester is pentaerythritol synthetic ester oil without any additives.

[0050] In this embodiment, the specific shapes of the blank oil sample and the mixed sample are referred to the relevant international standards, and the schematic diagram thereof can be as follows: Figure 2 shown.

[0051] Preferably, in order to avoid the experimental error caused by the sample itself as much as possible, the blank oil sample and the experimental oil sample can be subjected to the same pretreatment process.

[0052] In this embodiment, synthetic ester oil and insulating varnish are mixed according to volume (mL): surface area (cm 2 ) were mixed in a ratio of 12.5:1, and the experimental oil sample and the blank oil sample were placed in different vacuum drying ovens, and the temperature was set to 80°C, the air pressure was set to 50Pa, and the time was set to 48h.

[0053] Step 3: Take out the pretreated samples, place the blank oil samples and mixed samples in different aging tanks based on a certain ratio, degas the aging tanks and seal them.

[0054] In this embodiment, the degassing is to perform a vacuum treatment on the aging tank body containing the blank oil sample and the experimental oil sample, and after the vacuum treatment, the aging tank body is sealed.

[0055] Step 4: Place the aging tank in a constant temperature box, set the temperature and duration, and conduct an aging test.

[0056] Preferably, the temperature and duration of the thermostat can refer to relevant international standards, and the temperature in the thermostat can also be set according to actual needs. If it is necessary to test the compatibility of synthetic ester and insulating paint in a high temperature environment, the thermostat can be heated to a high temperature; if it is necessary to test the compatibility of synthetic ester and insulation in a low temperature environment, the thermostat can be lowered to a low temperature.

[0057] In this embodiment, the temperature of the constant temperature box is 130±2°C, and the duration is 168h, 336h, and 504h, that is, the cycle is 168h. A magnetic stirrer is installed during the aging test to ensure the fluidity of the oil during the test and simulate the flow of oil under actual operating conditions.

[0058] Step 5: After the aging time is completed, take out each sample and let it stand to cool to room temperature.

[0059] Specifically, when the aging time is 168 h, 336 h, and 504 h, the corresponding test samples are taken out respectively.

[0060] Step 6: Test the dielectric loss, acid value, kinematic viscosity, and moisture content of the blank oil sample and the oil sample in the experimental oil sample, and use different indicators before and after aging of the synthetic ester to complete the evaluation; test the hardness, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) of the insulating varnish in the experimental oil sample.

[0061] Preferably, the dielectric loss of the oil is the dielectric loss measured at 90° C., the kinematic viscosity is the kinematic viscosity measured at 40° C., and the hardness of the insulating varnish is Vickers hardness (HV).

[0062] Preferably, during the aging process, the duration of the intervals between taking out all samples should be kept consistent to avoid errors caused by unequal durations; performance tests are performed on samples before aging and after a certain aging time interval.

[0063] In this embodiment, the blank oil sample and the oil sample in the experimental oil sample were tested for acid value, 40° C. kinematic viscosity, and water content. The results are shown in Table 1.

[0064] Table 1- Index data of blank oil samples and experimental oil samples before and after aging

[0065]

[0066]

[0067] Step 7: Based on the performance indicator data obtained from the test, calculate the weight of each indicator in each cycle using the dynamic weighting method, such as Figure 3 shown.

[0068] In this embodiment, the calculations are all completed by Matlab software, and the dynamic weighting function is selected as a slightly large normal distribution function, and its expression is as follows: That The function graph is as follows Figure 4 As shown, W ik is the dynamic weight value of index i in the kth cycle, x is the value of the experimental oil sample index i in the kth cycle, ɑ k is the threshold value of a certain indicator in the kth cycle, which is defined as the value of blank oil sample indicator i in the kth cycle, σ k It can be selected according to the actual situation. If the rate of change in the first half of the cycle is greater than the rate of change in the second half of the cycle, then σ k The value is 0.3, otherwise it is 0.7; in this embodiment, σ kIt is always 0.3; when the value of the aged oil sample is better than or equal to (lower or higher than) this threshold, that is, the influence of the value on the judgment of compatibility is negligible, so the weight is 0; when it is worse than (higher or lower than) this threshold, the greater the rate of change between the kth cycle and the k-1th cycle, the greater the influence on the compatibility, so the higher the weight; calculate the rate of change of each cycle of different indicators compared with the blank oil sample and obtain the weight of each cycle based on dynamic weighting, the results are shown in Table 2 below.

[0069] Table 2- Weights of changes in different indicators of blank oil samples and experimental oil samples per cycle

[0070]

[0071] As shown in Table 2, the kinematic viscosity of the two insulating paint mixed oil samples did not change much, so their weights were relatively small, while the changes in acid value and moisture were relatively large, so their weights were relatively large, which is consistent with the intuitive speculation of the data.

[0072] In this embodiment, the insulating paint in the experimental oil sample was tested by scanning electron microscope (SEM), and the results are as follows: Figure 5-7 shown.

[0073] As attached Figure 5 As shown, there is little difference in kinematic viscosity between the blank oil sample and the two experimental oil samples, indicating that under the test conditions of this implementation example, the presence of insulating varnish does not significantly affect the kinematic viscosity of the oil. This may be because the interaction between insulating varnish and oil is limited and cannot be used as a criterion for judging compatibility. In addition, in the weight distribution ratio of this embodiment, the weight of kinematic viscosity is also the smallest.

[0074] As attached Figure 6-7 As shown in the figure, with the passage of aging time, the signs of corrosion on the surface and cross-section of No. 1 insulating paint become more and more obvious. After aging for 504 hours, the cross-section shows signs of degradation. However, the changes in the corrosion marks on the surface of No. 2 insulating paint are not obvious. After aging for 336 hours, holes can be seen on the surface. The insulating paint begins to gradually deteriorate, which also reflects that No. 2 insulating paint has stronger compatibility.

[0075] Step 8: Calculate the compatibility score based on the dynamic weight value of each indicator in each period. The dynamic weighted compatibility score expression of the i-th indicator in all periods is: The dynamic weighted compatibility score expression of all indicators in all periods is: Among them, Δ ik is the change rate of the ith indicator in the kth period. The change rate in the kth period is: (value in the kth period - value in the k-1th period) / (value in the kth period), W ikis the dynamic weight value of the ith index in the kth cycle, n is the number of test indexes, which are acid value, kinematic viscosity and moisture content, that is, n = 3 at this time, the compatibility score of synthetic ester and insulating varnish is calculated, and the compatibility grade is obtained according to the compatibility score evaluation table in Table 3. The flow chart of the compatibility score calculation procedure is shown in the attached figure. Figure 2 shown.

[0076] Table 3 - Compatibility evaluation table

[0077]

[0078] The results showed that the compatibility scores of the experimental oil sample (insulating varnish No. 1) and the experimental oil sample (insulating varnish No. 2) were 0.51 and 0.31 respectively, that is, the insulating varnish composed of unsaturated polyester resin is more compatible with this synthetic ester oil and can be used in combination with each other within a certain range.

[0079] The method for evaluating multiple properties of synthetic ester and insulating varnish based on dynamic weighting in this application can observe and analyze the evolution of the performance of synthetic ester and insulating varnish from multiple dimensions and angles, and assign different weights based on the degree of variation of each indicator under different aging time, so as to evaluate the compatibility more objectively, reliably and efficiently, and greatly improve the accuracy of the compatibility evaluation between synthetic ester and insulating varnish. At the same time, the compatibility under high temperature and low temperature environment can be evaluated, which is very important for understanding the compatibility and performance changes of materials under high temperature or low temperature environment, and whether there is a difference in the compatibility of materials with insulating oil under various temperature conditions can be determined.

[0080] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for evaluating the compatibility of synthetic ester and insulating varnish based on dynamic weighting, characterized in that: The following steps are involved: Synthetic ester is used as a blank oil sample, and a mixture of synthetic ester and insulating varnish is used as an experimental oil sample. The blank oil sample and the experimental oil sample are pre-treated with dehydration and degassing, respectively, and the treated samples are placed in a container, and the container is placed in an experimental temperature environment for an aging test, and 1-3 cycles are set; The blank oil samples and experimental oil samples after aging were taken out, and the electrical and physical and chemical performance indicators of the synthetic ester in the oil samples were tested respectively, and the performance indicators of the insulating paint were observed as auxiliary analysis; According to the performance index data of synthetic ester in blank oil samples and experimental oil samples, the dynamic weighted comprehensive evaluation method is used to calculate the compatibility score of synthetic ester and insulating varnish, and the compatibility score evaluation table is referred to to evaluate the degree of compatibility excellence.

2. A method for evaluating the compatibility of synthetic ester and insulating varnish based on dynamic weighting as claimed in claim 1, characterized in that: The dynamic weighted comprehensive evaluation method is to calculate the dynamic weight value of a certain performance indicator in a certain period according to the electrical and physical and chemical performance index data of the synthetic ester in the oil sample, and to weight the compatibility score of each indicator in each period according to the dynamic weight value of each indicator in each period and the index value change rate of each indicator in each period, and to accumulate the compatibility scores of all indicators in all periods, and to obtain the compatibility score of all indicators in all periods, and to obtain the compatibility grade by referring to the compatibility score evaluation table; The dynamic weight value is calculated according to the dynamic weighting function, which is selected as a slightly large normal distribution function, and its expression is: Where i is a performance index of synthetic ester in the oil sample, k is the period of the oil sample in the aging experiment, and W ik is the dynamic weight value of index i in the kth cycle, x is the value of the experimental oil sample index i in the kth cycle, ɑ k is the value of blank oil sample index i in the kth cycle, σ k It can be selected according to the actual situation. If the rate of change in the first half of the cycle is greater than the rate of change in the second half of the cycle, then σ k The value is 0.3, otherwise it is 0.7; According to the characteristics of the indicator data, when x is better than or equal to ɑ k When W ik is 0 when x is less than ɑ k hour, 3. A method for evaluating the compatibility of synthetic ester and insulating varnish based on dynamic weighting as claimed in claim 2, characterized in that: The aging test is divided into 3 cycles. The compatibility score is calculated based on the dynamic weight value of each indicator in each cycle and the indicator value change rate of each indicator in each cycle. The dynamic weighted compatibility score expression of the i-th indicator in all cycles is: The dynamic weighted compatibility score expression of all indicators in all periods is: Among them, Δ ik is the change rate of the ith indicator in the kth period. The change rate in the kth period is: (value in the kth period - value in the k-1th period) / (value in the kth period), W ik is the dynamic weight value of the ith indicator in the kth period, and n is the number of test performance indicators.

4. A method for evaluating the compatibility of synthetic ester and insulating varnish based on dynamic weighting as claimed in claim 3, characterized in that: The relationship between the Y value and the compatibility level in the compatibility evaluation table is as follows: When 0≤Y<0.2, they are compatible and can be used together; When 0.2≤Y<0.4, they are basically compatible, but there is a risk of incompatibility when they are matched in large quantities; When 0.4≤Y<0.6, the compatibility is poor, and when a large number of combinations are used, the risk of incompatibility is high; When 0.6≤Y≤1, they are extremely incompatible and cannot be used together.

5. The method for evaluating the compatibility of synthetic ester and insulating varnish based on dynamic weighting according to claim 1, characterized in that: Every 1cm in the experimental oil sample 2 Add 10-15mL of synthetic ester to the insulating paint mixture.

6. A method for evaluating the compatibility of synthetic ester and insulating varnish based on dynamic weighting as claimed in claim 1, characterized in that: The dehydration and degassing pretreatment is to place the experimental oil sample and the blank oil sample in different vacuum drying equipment, set the temperature to 60-100°C, set the air pressure to 40-60Pa, and set the time to 36-72h.

7. A method for evaluating the compatibility of synthetic ester and insulating varnish based on dynamic weighting as claimed in claim 1, characterized in that: The temperature of the aging test is 120-150°C, and the total aging time is 168-504h.

8. A method for evaluating the compatibility of synthetic ester and insulating varnish based on dynamic weighting as claimed in claim 1, characterized in that: The performance index of the synthetic ester in the blank oil sample and the experimental oil sample is at least one of dielectric loss, relative dielectric constant, volume resistivity, acid value, kinematic viscosity, and water content; the performance index test of the insulating varnish is at least one of hardness, scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis.

9. A method for evaluating the compatibility of synthetic ester and insulating varnish based on dynamic weighting as claimed in claim 8, characterized in that: The dielectric loss is the dielectric loss measured at 90°C, the kinematic viscosity is the kinematic viscosity measured at 40°C, and the hardness of the insulating varnish is the Vickers hardness.

10. The method for evaluating the compatibility of synthetic ester and insulating varnish based on dynamic weighting according to claim 1, characterized in that: The insulating varnish liquid is cured according to the conventional curing process and then mixed with synthetic ester as the experimental oil sample. The curing process of the insulating varnish is to maintain the temperature at 140-150°C for 1-3 hours, and then increase the temperature to 165-175°C at a heating rate of 2-3°C / min and maintain it for 6-8 hours.

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