A method for evaluating cable insulation materials with different voltage stability components

Abstract

This invention belongs to the field of insulating materials, and particularly relates to a method for evaluating cable insulation materials with different voltage stabilization components. The method includes the following steps: a) preparing a series of cable insulation material samples with different voltage stabilization components; b) measuring the conductivity, conductivity temperature sensitivity, DC breakdown field strength, and thermal conductivity of the cable insulation material samples to obtain measurement data for different cable insulation material samples; c) substituting the measurement data of each cable insulation material sample into the TOPSIS model to obtain a comprehensive score for each cable insulation material sample, with the voltage stabilization component corresponding to the cable insulation material sample with the highest comprehensive score being the optimal one. The method provided by this invention comprehensively evaluates cable insulation materials with different added voltage stabilization components while simultaneously considering both electrical and thermal characteristics, ensuring that the cable insulation materials have more comprehensive insulation performance and providing guidance for practical engineering applications.

Description

Technical Field

[0001] This invention belongs to the field of insulating materials, and in particular relates to a method for evaluating cable insulation materials with different voltage stability components. Background Technology

[0002] High-voltage direct current (HVDC) transmission systems are widely used in current power transmission networks due to their advantages such as unrestricted transmission capacity and distance. Because cable insulation is prone to space charge accumulation under a DC electric field, various methods have been used to improve the electrical withstand performance of cables to better adapt to the increasing DC operating voltage levels of the power grid. Adding voltage stabilizers is one of the important methods.

[0003] Currently, research on the optimized design of voltage-stabilizing components in cable insulation materials is relatively limited. While adding certain voltage stabilizers can indeed improve some insulation properties of cable insulation materials, such as DC breakdown field strength, the thermal conductivity and other performance indicators affecting insulation may deteriorate. Therefore, considering practical applications such as engineering, exploring a method for comprehensively evaluating cable insulation materials with different voltage-stabilizing components will play a crucial guiding role in the optimized design of voltage-stabilizing components in cable insulation materials. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for evaluating cable insulation materials with different voltage stabilization components. The method provided by this invention comprehensively evaluates cable insulation materials while simultaneously considering electrical and thermal characteristics. The evaluation results are more in line with the actual needs of engineering and have certain guiding significance for the optimized design of voltage stabilization components in cable insulation materials.

[0005] This invention provides a method for evaluating cable insulation materials with different voltage stability components, comprising the following steps:

[0006] a) Prepare a series of cable insulation material samples with different voltage-stabilizing components;

[0007] b) The conductivity, conductivity temperature sensitivity, DC breakdown field strength and thermal conductivity of the cable insulation material samples were measured to obtain measurement data for different cable insulation material samples;

[0008] c) Using the TOPSIS model, with conductivity and conductivity temperature sensitivity as cost indicators, and DC breakdown field strength and thermal conductivity as benefit indicators, the measurement data of each cable insulation material sample are substituted into the model to obtain a comprehensive score for each cable insulation material sample. The voltage stability component corresponding to the cable insulation material sample with the highest comprehensive score is the optimal one.

[0009] Preferably, in step a), the voltage-stabilizing components contained in the cable insulation material sample include one or more of 4-isopropoxybenzoic acid, 2,5-dimethoxyphenylboronic acid, and o-methoxyphenylboronic acid.

[0010] Preferably, in step a), the cable insulation material sample includes samples 1 to 7, and the voltage-stabilizing components contained therein are as follows:

[0011] The voltage-stabilizing component in Sample 1 is 4-isopropoxybenzoic acid;

[0012] The voltage-stabilizing component in Sample 2 is 2,5-dimethoxyphenylboronic acid;

[0013] The voltage-stabilizing component in sample 3 is o-methoxyphenylboronic acid;

[0014] The voltage-stabilizing components contained in Sample 4 are 4-isopropoxybenzoic acid, 2,5-dimethoxyphenylboronic acid and o-methoxyphenylboronic acid, with a mass ratio of 1:3:6.

[0015] The voltage-stabilizing components contained in sample 5 are 4-isopropoxybenzoic acid, 2,5-dimethoxyphenylboronic acid and o-methoxyphenylboronic acid, with a mass ratio of 6:1:3.

[0016] The voltage-stabilizing components contained in Sample 6 are 4-isopropoxybenzoic acid, 2,5-dimethoxyphenylboronic acid and o-methoxyphenylboronic acid, with a mass ratio of 3:6:1.

[0017] The voltage-stabilizing components contained in Sample 7 are 4-isopropoxybenzoic acid, 2,5-dimethoxyphenylboronic acid and o-methoxyphenylboronic acid, with a mass ratio of 1:1:1.

[0018] Preferably, in step a), the total amount of voltage-stabilizing components in the cable insulation material sample accounts for 0.5 to 2 wt% of the mass of the cable insulation material substrate.

[0019] Preferably, in step a), the total mass content of voltage-stabilizing components is the same in different cable insulation material samples.

[0020] Preferably, in step a), the cable insulation material substrate in the cable insulation material sample is cross-linked polyethylene.

[0021] Preferably, in step b), the conductivity includes the conductivity of the cable insulation material sample at multiple measurement temperatures.

[0022] Preferably, in step b), the conductivity measurement temperature includes 30°C, 50°C, and 70°C.

[0023] Preferably, in step b), the thermal conductivity includes the thermal conductivity of the cable insulation material sample at multiple measurement temperatures.

[0024] Preferably, in step b), the temperature for measuring the thermal conductivity includes 30°C, 50°C, and 70°C.

[0025] Compared with existing technologies, this invention provides a method for evaluating cable insulation materials with different voltage stabilizing components, comprising the following steps: a) preparing a series of cable insulation material samples with different voltage stabilizing components; b) measuring the conductivity, conductivity temperature sensitivity, DC breakdown field strength, and thermal conductivity of the cable insulation material samples to obtain measurement data for different cable insulation material samples; c) using the TOPSIS model, with conductivity and conductivity temperature sensitivity as cost indicators and DC breakdown field strength and thermal conductivity as benefit indicators, substituting the measurement data of each cable insulation material sample into the model to obtain a comprehensive score for each cable insulation material sample, and the voltage stabilizing component corresponding to the cable insulation material sample with the highest comprehensive score is considered optimal. The method provided by this invention comprehensively evaluates cable insulation materials with different added voltage stabilizing components while simultaneously considering electrical and thermal characteristics. The evaluation results are more in line with the needs of actual engineering and have certain guiding significance for the optimized design of voltage stabilizing components in cable insulation materials. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0027] This invention provides a method for evaluating cable insulation materials with different voltage stability components, comprising the following steps:

[0028] a) Prepare a series of cable insulation material samples with different voltage-stabilizing components;

[0029] b) The conductivity, conductivity temperature sensitivity, DC breakdown field strength and thermal conductivity of the cable insulation material samples were measured to obtain measurement data for different cable insulation material samples;

[0030] c) Using the TOPSIS model, conductivity and conductivity temperature sensitivity are used as cost indicators (i.e., the lower the better), and DC breakdown field strength and thermal conductivity are used as benefit indicators (i.e., the higher the better). The measurement data of each cable insulation material sample are substituted into the model to obtain a comprehensive score for each cable insulation material sample. The voltage stability component corresponding to the cable insulation material sample with the highest comprehensive score is the optimal one.

[0031] In the method provided by this invention, in step a), the cable insulation material sample contains a cable insulation material substrate and a voltage-stabilizing component; wherein, the cable insulation material substrate is preferably cross-linked polyethylene; and the density of the cross-linked polyethylene is preferably 0.9–0.95 g / cm³. 3 Specifically, it can be 0.922 g / cm³. 3 The melt flow rate (190℃ / 2.16kg) of the cross-linked polyethylene is preferably 1.5-2.5g / 10min, specifically 2g / 10min; the tensile strength of the cross-linked polyethylene is preferably ≥17MPa; the elongation at break of the cross-linked polyethylene is preferably ≥450%; the voltage-stabilizing component preferably includes one or more of 4-isopropoxybenzoic acid, 2,5-dimethoxyphenylboronic acid, and o-methoxyphenylboronic acid, wherein the chemical structure of 4-isopropoxybenzoic acid is shown in formula (I), the chemical structure of 2,5-dimethoxyphenylboronic acid is shown in formula (II), and the chemical structure of o-methoxyphenylboronic acid is shown in formula (III).

[0032]

[0033] In the method provided by this invention, in step a), the different voltage stabilizing components refer to the different types and / or contents of voltage stabilizers contained in the cable insulation material samples. In one embodiment of this invention, the cable insulation material samples include samples 1 to 7, and the voltage stabilizing components they contain are specifically as follows:

[0034] The voltage-stabilizing component in Sample 1 is 4-isopropoxybenzoic acid;

[0035] The voltage-stabilizing component in Sample 2 is 2,5-dimethoxyphenylboronic acid;

[0036] The voltage-stabilizing component in sample 3 is o-methoxyphenylboronic acid;

[0037] The voltage-stabilizing components contained in Sample 4 are 4-isopropoxybenzoic acid, 2,5-dimethoxyphenylboronic acid and o-methoxyphenylboronic acid, with a mass ratio of 1:3:6.

[0038] The voltage-stabilizing components contained in sample 5 are 4-isopropoxybenzoic acid, 2,5-dimethoxyphenylboronic acid and o-methoxyphenylboronic acid, with a mass ratio of 6:1:3.

[0039] The voltage-stabilizing components contained in Sample 6 are 4-isopropoxybenzoic acid, 2,5-dimethoxyphenylboronic acid and o-methoxyphenylboronic acid, with a mass ratio of 3:6:1.

[0040] The voltage-stabilizing components contained in Sample 7 are 4-isopropoxybenzoic acid, 2,5-dimethoxyphenylboronic acid and o-methoxyphenylboronic acid, with a mass ratio of 1:1:1.

[0041] In the method provided by this invention, in step a), the total amount of voltage-stabilizing components in the cable insulation material sample preferably accounts for 0.5 to 2 wt% of the mass of the cable insulation material substrate, specifically 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, or 2 wt%, with 1 wt% being the most preferred.

[0042] In the method provided by the present invention, in step a), the total mass content of voltage-stabilizing components in different cable insulation material samples is preferably the same.

[0043] In the method provided by this invention, in step a), the cable insulation material substrate in the cable insulation material sample is preferably cross-linked polyethylene; the density of the cross-linked polyethylene is preferably 0.9–0.95 g / cm³. 3 Specifically, it can be 0.922 g / cm³. 3 The melt flow rate (190℃ / 2.16kg) of the cross-linked polyethylene is preferably 1.5 to 2.5 g / 10 min, specifically 2 g / 10 min; the tensile strength of the cross-linked polyethylene is preferably ≥17 MPa; and the elongation at break of the cross-linked polyethylene is preferably ≥450%.

[0044] In the method provided by this invention, step a) preferably includes the following specific preparation steps for the cable insulation material sample:

[0045] The cable insulation material substrate and voltage stabilizing component are mixed, hot-pressed, and cooled to obtain a cable insulation material sample.

[0046] In the preparation steps provided by this invention, the mixing process preferably includes: mixing cable insulation material substrate powder, voltage stabilizing component powder, and volatile organic solvent, followed by solvent evaporation to obtain a blend of cable insulation material substrate and voltage stabilizer. Preferably, the cable insulation material substrate powder is prepared by grinding cable insulation material substrate after freeze-embrittlement; the voltage stabilizing component powder can be purchased directly; the volatile organic solvent is preferably ethanol; the mixing temperature is preferably 15–35°C, specifically 25°C (room temperature); the mixing time is preferably 1–5 hours, specifically 2 hours; and the solvent evaporation method is preferably rotary evaporation.

[0047] In the preparation steps provided by the present invention, the hot pressing temperature is preferably 150-200°C, specifically 180°C; the hot pressing pressure is preferably 18-25 MPa, specifically 20 MPa; and the hot pressing time is preferably 10-60 min, specifically 30 min.

[0048] In the preparation steps provided by the present invention, the cooling is preferably carried out under pressure holding conditions, that is, maintaining the pressure during hot pressing.

[0049] In the preparation steps provided by this invention, after cooling, the material obtained after cooling is preferably degassed to eliminate the influence of crosslinking byproducts. The degassed temperature is preferably 60–90°C, specifically 70°C; the degassed time is preferably 8–16 hours, specifically 12 hours.

[0050] In the method provided by the present invention, in step b), the conductivity preferably includes the conductivity of the cable insulation material sample at multiple measurement temperatures, the measurement temperatures preferably include 30°C, 50°C and 70°C; the electric field strength when measuring the conductivity is preferably 40 kV / mm; the polarization and depolarization times when measuring the conductivity are preferably 30 min and 15 min, respectively.

[0051] In the method provided by the present invention, in step b), the conductivity temperature sensitivity refers to the degree of sensitivity of conductivity to temperature, that is, the magnitude of the change in conductivity after the temperature increases.

[0052] In the method provided by this invention, in step b), the DC breakdown field strength is a technical indicator reflecting the DC breakdown resistance of the cable insulation material. The specific measurement process is as follows: a rapidly increasing DC voltage is applied to the measurement sample at room temperature until the sample breaks down. The voltage increase rate is preferably 1 kV / s. The test is repeated 12 times to obtain the Weibull distribution map of the DC breakdown field strength of the sample. The breakdown field strength at the 63.2% probability is taken as the breakdown result obtained from the statistical results.

[0053] In the method provided by the present invention, in step b), the thermal conductivity preferably includes the thermal conductivity of the cable insulation material sample at multiple measurement temperatures, the measurement temperatures preferably including 30°C, 50°C and 70°C.

[0054] In the method provided by this invention, in step c), the TOPSIS model is an evaluation model that ranks a finite number of evaluation objects based on their proximity to the ideal target. It evaluates the relative merits of existing objects and is a ranking evaluation model that approximates the ideal solution. The basic principle of the TOPSIS model is: ranking is performed by measuring the distance between the evaluation objects and the optimal and worst solutions. If an evaluation object is closest to the optimal solution and furthest from the worst solution, it is considered the best; otherwise, it is not optimal. Specifically, the optimal solution achieves the optimal value for each evaluation indicator, and the worst solution achieves the worst value for each evaluation indicator.

[0055] In the method provided by this invention, the specific process of data analysis and calculation using the TOPSIS model in step c) is as follows:

[0056] 1) Transform the original data matrix into a forward-oriented form, converting it entirely into extremely large indicators:

[0057]

[0058] Where x is the measured value of the indicator, f(x) is the positively oriented value, and in the calculation of the interval type indicator, M = max|x - best|.

[0059] 2) Standardize the normalized matrix to eliminate the influence of dimensions:

[0060]

[0061]

[0062] Where, x ij It is the j-th index of the i-th option. The N matrix represents m options (different evaluation objects). Each option has n indices (evaluation indicators) that need to be evaluated. f(xij) represents the normalized value, which are all benefit indicators. This means that a larger value represents better performance.

[0063] 3) Calculate the distance between each solution and the optimal and worst solutions:

[0064]

[0065]

[0066] in, The distance between the i-th option and the optimal solution The distance between the i-th option and the worst solution It is the maximum value among the j-th indicators. It is the minimum value among the j-th indicators. ω j This is the weight corresponding to the indicator.

[0067] 4) Score based on the overall distance of each option:

[0068]

[0069] Among them, F i It is the comprehensive distance score of the i-th option, which is a score that takes into account the distance between the option and both the optimal and worst solutions.

[0070] The method provided by this invention comprehensively evaluates cable insulation materials with different voltage-stabilizing components by considering both electrical and thermal properties. The evaluation results are more in line with the actual needs of engineering and have certain guiding significance for the optimized design of voltage-stabilizing components in cable insulation materials.

[0071] For clarity, the following examples will be used to provide a detailed description.

[0072] Example 1

[0073] Preparation of cable insulation material samples with different voltage stabilizing components:

[0074] In the preparation process described in this embodiment, the cross-linked polyethylene used has a density of 0.922 g / cm3, a melt flow rate (190℃ / 2.16 kg) of 2 g / 10 min, a tensile strength of 17 MPa, and an elongation at break of 450%.

[0075] Sample 1: 60g of cross-linked polyethylene was immersed in liquid nitrogen for freeze-brittle treatment, then ground into XLPE powder using an ultracentrifuge at 10000 rpm. 0.6g of 4-isopropoxybenzoic acid voltage stabilizer powder was added and mixed with the XLPE powder in ethanol solvent. After stirring thoroughly at room temperature for 2 hours, the ethanol solvent was removed by rotary evaporation to obtain a voltage stabilizer / XLPE blend. The blended powder was then placed in a mold and hot-pressed in a flat vulcanizing press at 180℃ and 20MPa for 30 minutes, followed by rapid cooling to room temperature under constant pressure to obtain an XLPE sample with a thickness of approximately 150μm containing 0.6g of 4-isopropoxybenzoic acid voltage stabilizer powder. Finally, to eliminate the influence of cross-linking byproducts, the sample was degassed in a vacuum oven at 70℃ for 12 hours.

[0076] Sample 2: 60g of cross-linked polyethylene was immersed in liquid nitrogen for freeze-brittle treatment, then ground into XLPE powder using an ultracentrifuge at 10000 r / min. 0.6g of 2,5-dimethoxyphenylboronic acid voltage stabilizer powder was added and mixed with the XLPE powder in ethanol solvent. After stirring thoroughly at room temperature for 2 hours, the ethanol solvent was removed by rotary evaporation to obtain a voltage stabilizer / XLPE blend. The blended powder was then placed in a mold and hot-pressed in a flat vulcanizing press at 180℃ and 20MPa for 30 minutes, followed by rapid cooling to room temperature under constant pressure to obtain an XLPE sample with a thickness of approximately 150μm containing 0.6g of 2,5-dimethoxyphenylboronic acid voltage stabilizer powder. Finally, to eliminate the influence of cross-linking byproducts, the sample was degassed in a vacuum oven at 70℃ for 12 hours.

[0077] Sample 3: 60g of cross-linked polyethylene was immersed in liquid nitrogen for freeze-brittle treatment, then ground into XLPE powder using an ultracentrifuge at 10000 r / min. 0.6g of o-methoxyphenylboronic acid voltage stabilizer powder was added and mixed with the XLPE powder in ethanol solvent. After stirring thoroughly at room temperature for 2 hours, the ethanol solvent was removed by rotary evaporation to obtain a voltage stabilizer / XLPE blend. The blended powder was then placed in a mold and hot-pressed in a flat vulcanizing press at 180℃ and 20MPa for 30 minutes, followed by rapid cooling to room temperature under constant pressure to obtain an XLPE sample with a thickness of approximately 150μm containing 0.6g of o-methoxyphenylboronic acid voltage stabilizer powder. Finally, to eliminate the influence of cross-linking byproducts, the sample was degassed in a vacuum oven at 70℃ for 12 hours.

[0078] Sample 4: 60g of cross-linked polyethylene was immersed in liquid nitrogen for freeze-brittle treatment, and then ground into XLPE powder in an ultracentrifuge at 10000 r / min. 0.06g of 4-isopropoxybenzoic acid voltage stabilizer powder, 0.18g of 2,5-dimethoxyphenylboronic acid, and 0.36g of o-methoxyphenylboronic acid were added, and the mixture was added to the XLPE powder in ethanol solvent. After stirring thoroughly at room temperature for 2 hours, the ethanol solvent was removed by rotary evaporation to obtain a voltage stabilizer / XLPE blend. The blended powder was then placed in a mold and hot-pressed in a flat vulcanizing machine at 180℃ and 20MPa for 30 minutes, followed by rapid cooling to room temperature under constant pressure to obtain an XLPE sample with a thickness of approximately 150μm containing 0.06g of 4-isopropoxybenzoic acid voltage stabilizer powder, 0.18g of 2,5-dimethoxyphenylboronic acid, and 0.36g of o-methoxyphenylboronic acid. Finally, to eliminate the influence of crosslinking byproducts, the sample was placed in a vacuum oven at 70°C for 12 hours to degas.

[0079] Sample 5: 60g of cross-linked polyethylene was immersed in liquid nitrogen for freeze-brittle treatment, and then ground into XLPE powder in an ultracentrifuge at 10000 r / min. 0.36g of 4-isopropoxybenzoic acid voltage stabilizer powder, 0.06g of 2,5-dimethoxyphenylboronic acid, and 0.18g of o-methoxyphenylboronic acid were added, and the mixture was added to the XLPE powder in ethanol solvent. After stirring thoroughly at room temperature for 2 hours, the ethanol solvent was removed by rotary evaporation to obtain a voltage stabilizer / XLPE blend. The blended powder was then placed in a mold and hot-pressed in a flat vulcanizing machine at 180℃ and 20MPa for 30 minutes, followed by rapid cooling to room temperature under constant pressure to obtain an XLPE sample with a thickness of approximately 150μm containing 0.36g of 4-isopropoxybenzoic acid voltage stabilizer powder, 0.06g of 2,5-dimethoxyphenylboronic acid, and 0.18g of o-methoxyphenylboronic acid. Finally, to eliminate the influence of crosslinking byproducts, the sample was placed in a vacuum oven at 70°C for 12 hours to degas.

[0080] Sample 6: 60g of cross-linked polyethylene was immersed in liquid nitrogen for freeze-brittle treatment, and then ground into XLPE powder in an ultracentrifuge at 10000 r / min. 0.18g of 4-isopropoxybenzoic acid voltage stabilizer powder, 0.36g of 2,5-dimethoxyphenylboronic acid, and 0.06g of o-methoxyphenylboronic acid were added, and the mixture was added to the XLPE powder in ethanol solvent. After stirring thoroughly at room temperature for 2 hours, the ethanol solvent was removed by rotary evaporation to obtain a voltage stabilizer / XLPE blend. The blended powder was then placed in a mold and hot-pressed in a flat vulcanizing machine at 180℃ and 20MPa for 30 minutes, followed by rapid cooling to room temperature under constant pressure to obtain an XLPE sample with a thickness of approximately 150μm containing 0.18g of 4-isopropoxybenzoic acid voltage stabilizer powder, 0.36g of 2,5-dimethoxyphenylboronic acid, and 0.06g of o-methoxyphenylboronic acid. Finally, to eliminate the influence of crosslinking byproducts, the sample was placed in a vacuum oven at 70°C for 12 hours to degas.

[0081] Sample 7: 60g of cross-linked polyethylene was immersed in liquid nitrogen for freeze-brittle treatment, and then ground into XLPE powder in an ultracentrifuge at 10000 r / min. 0.2g of 4-isopropoxybenzoic acid voltage stabilizer powder, 0.2g of 2,5-dimethoxyphenylboronic acid, and 0.2g of o-methoxyphenylboronic acid were added, and the mixture was added to the XLPE powder in ethanol solvent. After stirring thoroughly at room temperature for 2 hours, the ethanol solvent was removed by rotary evaporation to obtain a voltage stabilizer / XLPE blend. The blended powder was then placed in a mold and hot-pressed in a flat vulcanizing machine at 180℃ and 20MPa for 30 minutes, followed by rapid cooling to room temperature under constant pressure to obtain an XLPE sample with a thickness of approximately 150μm containing 0.2g of 4-isopropoxybenzoic acid voltage stabilizer powder, 0.2g of 2,5-dimethoxyphenylboronic acid, and 0.2g of o-methoxyphenylboronic acid. Finally, to eliminate the influence of crosslinking byproducts, the sample was placed in a vacuum oven at 70°C for 12 hours to degas.

[0082] Example 2

[0083] Performance measurement of cable insulation materials with different voltage stabilization components:

[0084] The electrical conductivity, electrical conductivity temperature sensitivity (the difference in electrical conductivity after temperature increase), DC breakdown field strength, and thermal conductivity of samples 1-7 prepared in Example 1 were measured. The specific measurement methods are as follows:

[0085] 1) Conductivity and conductivity temperature sensitivity: DC conduction current was measured at 30℃, 50℃ and 70℃ using a three-electrode system connected to Keithley 6517B under an electric field of 40kV / mm. The conductivity at different temperatures and the difference in conductivity after temperature increase were obtained. The polarization and depolarization times during the measurement were 30 minutes and 15 minutes, respectively.

[0086] 2) DC breakdown field strength: At room temperature, a rapidly increasing DC voltage (1kV / s) is applied to the cable insulation material until the sample breaks down. To prevent flashover, the ball plate electrode and the sample are placed in transformer oil. The test is repeated 12 times to obtain the Weibull distribution map of the DC breakdown field strength of the sample. The breakdown field strength at the 63.2% probability is taken as the breakdown result obtained by statistics.

[0087] 3) Thermal conductivity: The thermal conductivity of the sample at 30℃, 50℃ and 70℃ was measured using a DRL-III instrument (Xiangtan Instrument Co., Ltd.). During the measurement, thermally conductive silicon was coated on the surface of the test sample to ensure good contact between the electrode and the sample surface and heat transfer.

[0088] The performance measurement results are shown in Table 1:

[0089] Table 1 Performance measurement results of cable insulation material samples

[0090]

[0091]

[0092] Example 3

[0093] Based on the TOPSIS model, a comprehensive evaluation of cable insulation materials with different voltage stability components is conducted.

[0094] Using the difference between electrical conductivity and conductivity after temperature increase as cost-related indicators, and DC breakdown field strength and thermal conductivity as benefit-related indicators, the measurement data of each cable insulation material sample were substituted into the TOPSIS model for analysis and calculation. Each evaluation indicator (electrical conductivity, conductivity temperature sensitivity, DC breakdown field strength, and thermal conductivity) was assigned the same weight, and the weight of the same indicator at different temperatures was evenly distributed. The specific process and program code for data analysis and calculation using the TOPSIS model have been described above and will not be repeated here. The comprehensive evaluation results are shown in Table 2.

[0095] Table 2. TOPSIS model evaluation results of cable insulation material samples

[0096] plan Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Sample 7 Score 0.1088 0.1076 0.0700 0.1578 0.1764 0.1541 0.1318

[0097] As shown in Table 2, Sample 5 has the highest overall score and is the best. Its corresponding voltage-stabilizing components are: 0.6 wt% 4-isopropoxybenzoic acid, 0.1 wt% 2,5-dimethoxyphenylboronic acid and 0.3 wt% o-methoxyphenylboronic acid.

[0098] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for evaluating cable insulation materials with different voltage stability components, comprising the following steps: a) Prepare a series of cable insulation material samples with different voltage-stabilizing components; b) The conductivity, conductivity temperature sensitivity, DC breakdown field strength and thermal conductivity of the cable insulation material samples were measured to obtain measurement data for different cable insulation material samples; In step b), the electrical conductivity includes the electrical conductivity of the cable insulation material sample at multiple measurement temperatures, including 30°C, 50°C, and 70°C; the thermal conductivity includes the thermal conductivity of the cable insulation material sample at multiple measurement temperatures, including 30°C, 50°C, and 70°C. c) Using the TOPSIS model, with conductivity and conductivity temperature sensitivity as cost indicators, and DC breakdown field strength and thermal conductivity as benefit indicators, the measurement data of each cable insulation material sample are substituted into the model to obtain a comprehensive score for each cable insulation material sample. The voltage stability component corresponding to the cable insulation material sample with the highest comprehensive score is the optimal one.

2. The method according to claim 1, characterized in that, In step a), the voltage-stabilizing components contained in the cable insulation material sample include one or more of 4-isopropoxybenzoic acid, 2,5-dimethoxyphenylboronic acid, and o-methoxyphenylboronic acid.

3. The method according to claim 1, characterized in that, In step a), the cable insulation material samples include samples 1 to 7, and the voltage-stabilizing components they contain are as follows: The voltage-stabilizing component in Sample 1 is 4-isopropoxybenzoic acid; The voltage-stabilizing component in Sample 2 is 2,5-dimethoxyphenylboronic acid; The voltage-stabilizing component in sample 3 is o-methoxyphenylboronic acid; The voltage-stabilizing components contained in Sample 4 are 4-isopropoxybenzoic acid, 2,5-dimethoxyphenylboronic acid and o-methoxyphenylboronic acid, with a mass ratio of 1:3:

6. The voltage-stabilizing components contained in sample 5 are 4-isopropoxybenzoic acid, 2,5-dimethoxyphenylboronic acid and o-methoxyphenylboronic acid, with a mass ratio of 6:1:

3. The voltage-stabilizing components contained in Sample 6 are 4-isopropoxybenzoic acid, 2,5-dimethoxyphenylboronic acid and o-methoxyphenylboronic acid, with a mass ratio of 3:6:

1. The voltage-stabilizing components contained in Sample 7 are 4-isopropoxybenzoic acid, 2,5-dimethoxyphenylboronic acid and o-methoxyphenylboronic acid, with a mass ratio of 1:1:

1.

4. The method according to claim 1, characterized in that, In step a), the total amount of voltage-stabilizing components in the cable insulation material sample accounts for 0.5 to 2 wt% of the mass of the cable insulation material substrate.

5. The method according to claim 1, characterized in that, In step a), the total mass content of voltage-stabilizing components is the same in the different cable insulation material samples.

6. The method according to claim 1, characterized in that, In step a), the cable insulation material substrate in the cable insulation material sample is cross-linked polyethylene.

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