Cable insulation material charge transport characteristic evaluation method based on polarization current

Abstract

The invention discloses a polarization current-based cable insulation material charge transport characteristic evaluation method, and belongs to the technical field of high-voltage cable health state evaluation, and the method comprises the steps: S1, obtaining a current curve based on the polarization current and depolarization current of a cable, and obtaining a trap distribution condition based on the current curve; s2, the conductivity of the cable insulation material is obtained based on the radius of the conductivity in the cable, the total space charge change amount of the cable insulation material is obtained based on the depolarization current, and the carrier mobility of the cable insulation material is obtained based on the conductivity and the total space charge change amount; and S3, evaluating the charge transport characteristics of the cable insulation material based on the trap distribution condition and the carrier mobility. The problem that the service life evaluation accuracy of the cable insulation material is low due to the fact that the service life evaluation of the cable insulation material depends on a single parameter is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of high voltage cable health status assessment, and in particular to a method for assessing the charge transport characteristics of cable insulation materials based on polarization current. Background Art

[0002] With the continuous advancement of power transmission technology, it is increasingly critical to ensure the safe and stable operation of the power system. As an indispensable part of the power transmission and distribution system, the performance of the insulation material of the cable has a direct and significant impact on the stability of the entire power system. However, during the long-term operation of the cable, due to the combined effect of a variety of complex factors, the charge distribution inside the material will change, which will in turn affect the insulation performance and service life of the cable. The existing technology mainly evaluates the life of the cable insulation material by the conductive current density. For example, patent number CN116106702A is an insulation aging life assessment method and system based on insulation leakage current, which includes the following steps: conducting polarization and depolarization current test experiments on power cables with different known operating years, and obtaining polarization and depolarization current test data of the cable insulation material; making three assumptions about the aging life of the cable insulation material, Based on these three assumptions, the relationship between the aging life of the cable insulation material and the conductivity current density of the cable is derived; the polarization and depolarization current test data of the cable insulation material and the derived relationship between the aging life of the cable insulation material and the conductivity current density of the cable are quantitatively correlated to determine the relationship between the aging life of the cable insulation material and the conductivity current density of the cable, and then the cable life is evaluated. However, the above scheme only relies on the single parameter of conductivity current density to evaluate the life of the cable insulation material, and a single parameter is difficult to accurately reflect the aging state of the cable insulation material, which will lead to misjudgment of the life of the cable insulation material. Summary of the invention

[0003] The existing technology relies on a single parameter to evaluate the life of cable insulation materials, resulting in low accuracy in the evaluation of the life of cable insulation materials. The present invention provides a method for evaluating the charge transport characteristics of cable insulation materials based on polarization current, which characterizes the movement speed of charges in cable insulation materials by calculating carrier mobility, characterizes the characteristics of defects or energy states that can capture charges inside cable insulation materials by obtaining trap distribution, and then comprehensively evaluates the charge transport characteristics of cable insulation materials by integrating carrier mobility and trap distribution, thereby achieving a multi-dimensional and in-depth evaluation of the charge transport characteristics of cable insulation materials, and solving the problem of low accuracy in the evaluation of the life of cable insulation materials due to reliance on a single parameter to evaluate the life of cable insulation materials. The accuracy of the evaluation of the life of cable insulation materials is significantly improved.

[0004] In order to solve the above technical problems, the present invention provides a method for evaluating the charge transport characteristics of cable insulation materials based on polarization current, comprising the following steps: S1: Obtain the current curve based on the polarization current and depolarization current of the cable, and obtain the trap distribution based on the current curve; S2: The conductivity of the cable insulation material is obtained based on the radius of the conductor in the cable, the total amount of spatial charge change of the cable insulation material is obtained based on the depolarization current, and the carrier mobility of the cable insulation material is obtained based on the conductivity and the total amount of spatial charge change; S3: The charge transport characteristics of the cable insulation material are evaluated based on the trap distribution and carrier mobility.

[0005] After adopting the above technical solution, the present invention has the following advantages: Considering that the carrier mobility represents the speed of charge movement in the cable insulation material, and the trap distribution represents the characteristics of the defects or energy states inside the cable insulation material that can capture charges, the life of the cable insulation material is evaluated from two aspects: charge transfer efficiency and internal microstructure of the cable insulation material by obtaining the carrier mobility and trap distribution. These two aspects of information complement each other and together constitute a comprehensive and in-depth evaluation system, which realizes a multi-dimensional and in-depth evaluation of the charge transport characteristics of the cable insulation material, and significantly improves the accuracy of the life evaluation of the cable insulation material; it solves the problem of low accuracy of the life evaluation of the cable insulation material due to relying on a single parameter to evaluate the life of the cable insulation material.

[0006] Preferably, the S1 comprises: S11: obtaining a polarization current curve and a depolarization current curve based on the polarization current and the depolarization current of the cable respectively, and performing smoothing on the polarization current curve and the depolarization current curve; S12: extracting first key data from the polarization current curve based on the influencing factors of the charge distribution inside the cable insulation material, extracting second key data from the depolarization current curve based on the trap capture influencing factors, and obtaining the trap distribution based on the first key data and the second key data.

[0007] Considering that the process of obtaining polarization current and depolarization current will be affected by factors such as noise and measurement error, the curve is smoothed to eliminate interference factors and make the curve closer to the actual situation. The first key data reflects the influencing factors of charge distribution inside the cable insulation material, and the second key data mainly reflects the situation of trap capture charge. The trap distribution can be obtained by the first key data and the second key data, and the distribution of the trap can be obtained more accurately.

[0008] Preferably, in S2, the expression for obtaining the conductivity of the cable insulation material based on the radius of the conductivity in the cable is: Where σ is the conductivity, I is the current in the conductor, r is the radius of the conductor, R is the outer radius of the cable insulation material, L is the length of the outer semi-conductive layer, and g is the distance between the copper shielding ring and the outer semi-conductive layer.

[0009] Preferably, in S2, obtaining the carrier mobility of the cable insulation material based on the total amount of conductivity and space charge change includes: The carrier concentration of the cable insulation material is obtained based on the total amount of space charge change, and the carrier mobility is obtained based on the carrier concentration and conductivity.

[0010] Preferably, the expression for obtaining the carrier concentration of the cable insulation material based on the total amount of space charge change is: Wherein, n is the carrier concentration, θ is the conductivity, a is the outer radius of the cable insulation material, and d is the thickness of the cable insulation material.

[0011] Preferably, the expression for obtaining carrier mobility based on carrier concentration and conductivity is: Where μ is the carrier mobility and q is the electron charge.

[0012] Preferably, S3 includes: S31: based on the characteristics of the cable insulation material, a preset peak value and a preset mobility are obtained, and it is determined whether the third peak value of the trap distribution curve in the trap distribution condition is greater than the preset peak value. If it is greater than, it indicates that the charge transport characteristics of the cable insulation material do not meet the requirements. If it is less than or equal to the preset peak value, S32 is executed; S32: Determine whether the carrier mobility is greater than the preset mobility. If it is greater than, it indicates that the charge transport characteristics of the cable insulation material do not meet the requirements. If it is less than or equal to the preset mobility, it indicates that the charge transport characteristics of the cable insulation material meet the requirements. Since the higher the carrier mobility, the longer the aging time of the high-voltage cable insulation material, the longer the aging time, the higher the third peak of the trap distribution curve. Therefore, the charge transport characteristics of the cable insulation material can be evaluated by the carrier mobility and the trap distribution curve. The carrier mobility and the trap distribution are used to evaluate the life of the cable insulation material from two aspects: charge transfer efficiency and the internal microstructure of the cable insulation material. The two aspects of information complement each other and together constitute a comprehensive and in-depth evaluation system, which realizes a multi-dimensional and in-depth evaluation of the charge transport characteristics of the cable insulation material, and significantly improves the accuracy of the life evaluation of the cable insulation material.

[0013] Beneficial effects of this program: Considering that the carrier mobility represents the speed of charge movement in the cable insulation material, and the trap distribution represents the characteristics of the defects or energy states inside the cable insulation material that can capture charges, the life of the cable insulation material is evaluated from two aspects: charge transfer efficiency and internal microstructure of the cable insulation material by obtaining the carrier mobility and trap distribution. These two aspects of information complement each other and together constitute a comprehensive and in-depth evaluation system, which realizes a multi-dimensional and in-depth evaluation of the charge transfer characteristics of the cable insulation material, and significantly improves the accuracy of the life evaluation of the cable insulation material; it solves the problem of low accuracy of the life evaluation of the cable insulation material due to relying on a single parameter to evaluate the life of the cable insulation material.

[0014] The present invention also provides a system for evaluating the charge transport characteristics of cable insulation materials based on polarization current, comprising: Multi-dimensional data acquisition module, used to obtain trap distribution and carrier mobility of cable insulation materials; Comprehensive evaluation module for evaluating the charge transport properties of cable insulation materials based on trap distribution and carrier mobility.

[0015] The multi-dimensional data acquisition module includes a trap distribution acquisition module and a carrier mobility acquisition module; The trap distribution acquisition module is used to acquire a current curve based on the polarization current and depolarization current of the cable, and acquire the trap distribution based on the current curve; The carrier mobility acquisition module is used to acquire the carrier mobility of the cable insulation material based on the total amount of conductivity and space charge change.

[0016] The comprehensive evaluation module includes a first judgment module and a second judgment module; The first judgment module is used to judge whether the third peak of the trap distribution curve in the trap distribution condition is greater than a preset peak value, and when judging that the third peak value is less than or equal to the preset peak value, prompt the second judgment module to judge whether the carrier mobility is greater than the preset mobility.

[0017] Beneficial effects of this program: Considering that the carrier mobility represents the speed of charge movement in the cable insulation material, and the trap distribution represents the characteristics of the defects or energy states inside the cable insulation material that can capture the charge, the carrier mobility and trap distribution are obtained through the multi-dimensional data acquisition module to evaluate the life of the cable insulation material from two aspects: charge transfer efficiency and internal microstructure of the cable insulation material. The two aspects of information complement each other and together constitute a comprehensive and in-depth evaluation system, which realizes a multi-dimensional and in-depth evaluation of the charge transport characteristics of the cable insulation material, and significantly improves the accuracy of the life evaluation of the cable insulation material; The problem of low accuracy in life assessment of cable insulation materials due to reliance on a single parameter for assessing the life of cable insulation materials is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings. The drawings are only for the purpose of illustrating preferred embodiments and are not to be considered as limiting the present invention. Also, the same reference symbols are used throughout the drawings to represent the same parts.

[0019] Figure 1 The method flow chart of the method for evaluating the charge transport characteristics of cable insulation materials based on polarization current of the present invention; Figure 2 Depolarization current curves of the cable insulation material of the present invention at different aging times; Figure 3 is the trap distribution curve of the cable insulation material of the present invention at different aging times; Figure 4 The total amount curve of space charge change of the cable insulation material of the present invention at different aging times; Figure 5 The carrier mobility curves of the cable insulation material of the present invention at different aging times. DETAILED DESCRIPTION

[0020] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation method described herein is only an optimal embodiment of the present invention, which is only used to explain the present invention and does not limit the scope of protection of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow charts describe the operations (or steps) as sequential processes, many of the operations (or steps) therein can be implemented in parallel, concurrently, or simultaneously. In addition, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but can also have additional steps not included in the drawings; the process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0022] Embodiment 1: like Figure 1 As shown, the method for evaluating the charge transport characteristics of cable insulation materials based on polarization current includes the following steps: S1: Obtain the current curve based on the polarization current and depolarization current of the cable, and obtain the trap distribution based on the current curve.

[0023] The S1 includes: S11: obtaining a polarization current curve and a depolarization current curve based on the polarization current and the depolarization current of the cable respectively, and performing smoothing on the polarization current curve and the depolarization current curve; S12: extracting first key data from the polarization current curve based on the influencing factors of the charge distribution inside the cable insulation material, extracting second key data from the depolarization current curve based on the trap capture influencing factors, and obtaining the trap distribution based on the first key data and the second key data.

[0024] In this embodiment, a 30cm long XLPE cable with an insulation thickness of 3mm was selected, and the same cable was subjected to heat aging for 4, 7, 10, and 14 days, respectively. For the cable sample, the outer sheath, water-blocking layer, copper shielding layer, etc. of the cable were first stripped off to expose the outer semi-conductive layer as the measuring electrode, and then a certain length of the outer semi-conductive layer on both sides of the cable was stripped off to expose the insulating layer. Two copper shielding rings were added to both ends of the insulating layer and grounded as protective electrodes to avoid the influence of surface leakage current on the polarization / depolarization current measurement of the cable insulation layer. Finally, the copper core at both ends of the cable was exposed as a high-voltage electrode. The polarization current i of the high-voltage cable was measured at different voltage levels. p With the depolarizing current i dp For example, the depolarization current obtained by the polarization depolarization current test at a voltage of 5 kV is as follows Figure 2 As shown, using formula i d =|i dp |-|I dpf |Calculate the isothermal relaxation current of the high-voltage cable insulation material, where i d is the isothermal relaxation current, i dp is the depolarization current, i dpf is the depolarization current i dp The value tends to be stable during the test time. For high-voltage cables with different aging degrees, the first key data obtained is the isothermal relaxation current i d The second key data is the current decay time t d The product of is the trap level density, and lnt d Indicates the trap depth, i d ·t d / σ1~lnt d The curve represents the relationship between the trapped charge density in the insulating medium and the corresponding trap depth. The trap depth is calculated according to the following formula: d =kTln(vt d), where k is the Boltzmann constant, T is the Kelvin temperature, and v is the electron vibration frequency. The trap distribution of insulating materials with different aging degrees is compared, such as Figure 3 The calculated trap distribution curves of cable insulation materials without aging, aging for 4, 7, 10, and 14 days are shown in Figure 2. As the aging time increases, the third peak of the trap distribution curve gradually increases and is higher than the first two peaks, indicating that the interface polarization affected by aging is dominant. The trap distribution curve is used to characterize the characteristics of defects or energy states that can capture charges inside the cable insulation material, and the life of the cable insulation material is evaluated from the internal microstructure of the cable insulation material, which improves the accuracy of the life evaluation of the cable insulation material.

[0025] S2: The conductivity of the cable insulation material is obtained based on the radius of the conductor in the cable, the total amount of space charge change of the cable insulation material is obtained based on the depolarization current, and the carrier mobility of the cable insulation material is obtained based on the conductivity and the total amount of space charge change.

[0026] In S2, the expression for obtaining the conductivity of the cable insulation material based on the radius of the conductivity in the cable is: Where σ is the conductivity, I is the current in the conductor, r is the radius of the conductor, R is the outer radius of the cable insulation material, L is the length of the outer semi-conductive layer, and g is the distance between the copper shielding ring and the outer semi-conductive layer.

[0027] In S2, the obtaining of carrier mobility of the cable insulation material based on the conductivity and the total amount of space charge change includes: obtaining the carrier concentration of the cable insulation material based on the total amount of space charge change, and obtaining the carrier mobility based on the carrier concentration and the conductivity.

[0028] The expression for obtaining the carrier concentration of the cable insulation material based on the total amount of space charge change is: Wherein, n is the carrier concentration, θ is the conductivity, a is the outer radius of the cable insulation material, and d is the thickness of the cable insulation material.

[0029] The expression for obtaining carrier mobility based on carrier concentration and conductivity is: Where μ is the carrier mobility and q is the electron charge.

[0030] Polarization and depolarization current tests were conducted on cables that were not aged, aged for 4, 7, 10, and 14 days. In the formula, σ is the conductivity, I is the current in the conductivity, r is the radius of the conductivity, R is the outer radius of the cable insulation material, L is the length of the outer semi-conductive layer, g is the distance between the copper shielding ring and the outer semi-conductive layer, and the conductivity of the cable insulation material is calculated. The calculation results are shown in Table 1: Table 1. Conductivity of cable insulation materials at different aging times Aging time Aging 1 week Aging 3 weeks Aging 5 weeks Aging 7 weeks <![CDATA[Conductivity / S·m -1 > <![CDATA[1.86×10 -17 ]]> <![CDATA[7.31×10 -17 ]]> <![CDATA[8.81×10 -17 ]]> <![CDATA[1.19×10 -16 ]]> The longer the cable insulation material ages, the greater its conductivity. The amount of charge dissipated by the high-voltage cable insulation material during the depolarization phase is calculated using the formula: Where, σ1 is the amount of dissipated charge; S is the area of ​​the current test electrode; t is the test time; i dp The total space charge change of the cable insulation material without aging, aging for 4, 7, 10, and 14 days under different voltages is calculated as follows: Figure 4 As shown. Based on the carrier concentration and conductivity, the carrier mobility is obtained, and the calculation results are shown as follows Figure 5 As shown in the figure, the longer the cable insulation material ages, the higher its carrier mobility. The carrier mobility is used to characterize the speed at which charges move in the cable insulation material, and the life of the cable insulation material is evaluated from the charge transfer efficiency, which improves the accuracy of the cable insulation material life evaluation.

[0031] S3: Evaluation of the charge transport properties of cable insulation materials based on trap distribution and carrier mobility.

[0032] The S3 includes: S31: based on the characteristics of the cable insulation material, a preset peak value and a preset mobility are obtained, and it is determined whether the third peak value of the trap distribution curve in the trap distribution condition is greater than the preset peak value. If it is greater than, it indicates that the charge transport characteristics of the cable insulation material do not meet the requirements. If it is less than or equal to the preset peak value, S32 is executed; S32: Determine whether the carrier mobility is greater than a preset mobility. If it is greater than, it indicates that the charge transport characteristics of the cable insulation material do not meet the requirements. If it is less than or equal to the preset mobility, it indicates that the charge transport characteristics of the cable insulation material meet the requirements.

[0033] Reference is made to industry standards or specifications for cable insulation materials to obtain a preset peak value and a preset mobility.

[0034] As an implementation manner, the trap distribution curve of the insulating material may also be obtained through experimental measurement, and a preset peak value may be obtained according to the trap distribution curve of the insulating material.

[0035] The life of cable insulation materials is evaluated from two aspects, charge transfer efficiency and internal microstructure of cable insulation materials, through multi-carrier mobility and trap distribution. These two aspects of information complement each other and together constitute a comprehensive and in-depth evaluation system, which realizes a multi-dimensional and in-depth evaluation of the charge transport characteristics of cable insulation materials and significantly improves the accuracy of life assessment of cable insulation materials.

[0036] Embodiment 2: This embodiment also provides a system for evaluating the charge transport characteristics of cable insulation materials based on polarization current, including: Multi-dimensional data acquisition module, used to obtain trap distribution and carrier mobility of cable insulation materials; Comprehensive evaluation module for assessing the charge transport properties of cable insulation materials based on trap distribution and carrier mobility.

[0037] The multi-dimensional data acquisition module includes a trap distribution acquisition module and a carrier mobility acquisition module; The trap distribution acquisition module is used to acquire a current curve based on the polarization current and depolarization current of the cable, and acquire the trap distribution based on the current curve; The carrier mobility acquisition module is used to acquire the carrier mobility of the cable insulation material based on the total amount of conductivity and space charge change.

[0038] The comprehensive evaluation module includes a first judgment module and a second judgment module; The first judgment module is used to judge whether the third peak of the trap distribution curve in the trap distribution condition is greater than a preset peak value, and when judging that the third peak value is less than or equal to the preset peak value, prompt the second judgment module to judge whether the carrier mobility is greater than the preset mobility.

[0039] In this example, a 30 cm long XLPE cable with an insulation thickness of 3 mm was selected, and the same cable was subjected to heat aging for 4, 7, 10, and 14 days. The polarization current i of the high-voltage cable was measured at different voltage levels. p With the depolarizing current i dp For example, the depolarization current obtained by the polarization depolarization current test at a voltage of 5 kV is as follows Figure 2 As shown in the figure, for high-voltage cables with different aging degrees, the first key data obtained is the isothermal relaxation current i d The second key data is the current decay time t d The product of is the trap level density, and lnt d Indicates the trap depth, i d ·t d / σ1~lnt d The curve represents the relationship between the trapped charge density in the insulating medium and the corresponding trap depth. The trap depth is calculated according to the following formula: d =kTln(vt d ), where k is the Boltzmann constant, T is the Kelvin temperature, and v is the electron vibration frequency. The trap distribution of insulating materials with different aging degrees is compared, such as Figure 3The calculated trap distribution curves of cable insulation materials without aging, aging for 4, 7, 10, and 14 days are shown in Figure 2. As the aging time increases, the third peak of the trap distribution curve gradually increases and is higher than the first two peaks, indicating that the interface polarization affected by aging is dominant. The trap distribution curve is used to characterize the characteristics of defects or energy states that can capture charges inside the cable insulation material, and the life of the cable insulation material is evaluated from the internal microstructure of the cable insulation material, which improves the accuracy of the life evaluation of the cable insulation material.

[0040] Polarization and depolarization current tests were conducted on cables that were not aged, aged for 4, 7, 10, and 14 days. In the formula, σ is the conductivity, I is the current in the conductivity, r is the radius of the conductivity, R is the outer radius of the cable insulation material, L is the length of the outer semi-conductive layer, g is the distance between the copper shielding ring and the outer semi-conductive layer, and the conductivity of the cable insulation material is calculated. The longer the aging time of the cable insulation material, the greater its conductivity. The amount of charge dissipated by the high-voltage cable insulation material in the depolarization stage is calculated as follows: Where, σ1 is the total amount of space charge change, i.e., the amount of dissipated charge; S is the area of ​​the current test electrode; t is the test time; i dp The total space charge change of the cable insulation material without aging, aging for 4, 7, 10, and 14 days under different voltages is calculated as follows: Figure 4 As shown. Based on the carrier concentration and conductivity, the carrier mobility is obtained, and the calculation results are shown as follows Figure 5 As shown in the figure, the longer the cable insulation material ages, the higher its carrier mobility. The carrier mobility is used to characterize the speed at which charges move in the cable insulation material, and the life of the cable insulation material is evaluated from the charge transfer efficiency, which improves the accuracy of the cable insulation material life evaluation.

[0041] Reference is made to industry standards or specifications for cable insulation materials to obtain a preset peak value and a preset mobility.

[0042] As an implementation manner, the trap distribution curve of the insulating material may also be obtained through experimental measurement, and a preset peak value may be obtained according to the trap distribution curve of the insulating material.

[0043] The life of cable insulation materials is evaluated from two aspects, charge transfer efficiency and internal microstructure of cable insulation materials, through multi-carrier mobility and trap distribution. These two aspects of information complement each other and together constitute a comprehensive and in-depth evaluation system, which realizes a multi-dimensional and in-depth evaluation of the charge transport characteristics of cable insulation materials and significantly improves the accuracy of life assessment of cable insulation materials.

[0044] The specific implementation modes described above are preferred implementation modes of the present invention, and are not intended to limit the specific implementation scope of the present invention. The scope of the present invention includes but is not limited to the specific implementation modes. All equivalent changes made in accordance with the shape and structure of the present invention are within the protection scope of the present invention.

Claims

1. A method for evaluating the charge transport characteristics of cable insulation materials based on polarization current, characterized in that: The following steps are involved: S1: Obtain the current curve based on the polarization current and depolarization current of the cable, and obtain the trap distribution based on the current curve; S2: Obtain the conductivity of the cable insulation material based on the radius of the conductor in the cable, obtain the total amount of space charge change of the cable insulation material based on the depolarization current, and obtain the carrier mobility of the cable insulation material based on the conductivity and the total amount of space charge change; S3: Evaluation of the charge transport properties of cable insulation materials based on trap distribution and carrier mobility.

2. The method for evaluating the charge transport characteristics of cable insulation materials based on polarization current according to claim 1, characterized in that: The S1 includes: S11: obtaining a polarization current curve and a depolarization current curve based on the polarization current and the depolarization current of the cable respectively, and performing smoothing on the polarization current curve and the depolarization current curve; S12: extracting first key data from the polarization current curve based on the influencing factors of the charge distribution inside the cable insulation material, extracting second key data from the depolarization current curve based on the trap capture influencing factors, and obtaining the trap distribution based on the first key data and the second key data.

3. The method for evaluating the charge transport characteristics of cable insulation materials based on polarization current according to claim 1, characterized in that: In S2, the expression for obtaining the conductivity of the cable insulation material based on the radius of the conductivity in the cable is: Where σ is the conductivity, I is the current in the conductor, r is the radius of the conductor, R is the outer radius of the cable insulation material, L is the length of the outer semi-conductive layer, and g is the distance between the copper shielding ring and the outer semi-conductive layer.

4. The method for evaluating the charge transport characteristics of cable insulation materials based on polarization current according to claim 1, characterized in that: In S2, obtaining the carrier mobility of the cable insulation material based on the total amount of conductivity and space charge change includes: The carrier concentration of the cable insulation material is obtained based on the total amount of space charge change, and the carrier mobility is obtained based on the carrier concentration and conductivity.

5. The method for evaluating the charge transport characteristics of cable insulation materials based on polarization current according to claim 4, characterized in that: The expression for obtaining the carrier concentration of the cable insulation material based on the total amount of space charge change is: Wherein, n is the carrier concentration, θ is the conductivity, a is the outer radius of the cable insulation material, and d is the thickness of the cable insulation material.

6. The method for evaluating the charge transport characteristics of cable insulation materials based on polarization current according to claim 5, characterized in that: The expression for obtaining carrier mobility based on carrier concentration and conductivity is: Where μ is the carrier mobility and q is the electron charge.

7. The method for evaluating the charge transport characteristics of cable insulation materials based on polarization current according to claim 1, characterized in that: The S3 includes: S31: based on the characteristics of the cable insulation material, a preset peak value and a preset mobility are obtained, and it is determined whether the third peak value of the trap distribution curve in the trap distribution condition is greater than the preset peak value. If it is greater than, it indicates that the charge transport characteristics of the cable insulation material do not meet the requirements. If it is less than or equal to the preset peak value, S32 is executed; S32: Determine whether the carrier mobility is greater than a preset mobility. If it is greater than, it indicates that the charge transport characteristics of the cable insulation material do not meet the requirements. If it is less than or equal to the preset mobility, it indicates that the charge transport characteristics of the cable insulation material meet the requirements.

8. A system for evaluating the charge transport characteristics of cable insulation materials based on polarization current, applicable to the method for evaluating the charge transport characteristics of cable insulation materials based on polarization current according to any one of claims 1 to 7, characterized in that: include: Multi-dimensional data acquisition module, used to obtain trap distribution and carrier mobility of cable insulation materials; Comprehensive evaluation module for evaluating the charge transport properties of cable insulation materials based on trap distribution and carrier mobility.

9. The cable insulation material charge transport characteristic evaluation system based on polarization current according to claim 8, characterized in that: The multi-dimensional data acquisition module includes a trap distribution acquisition module and a carrier mobility acquisition module; The trap distribution acquisition module is used to acquire a current curve based on the polarization current and depolarization current of the cable, and acquire the trap distribution based on the current curve; The carrier mobility acquisition module is used to acquire the carrier mobility of the cable insulation material based on the total amount of conductivity and space charge change.

10. The cable insulation material charge transport characteristic evaluation system based on polarization current according to claim 8, characterized in that: The comprehensive evaluation module includes a first judgment module and a second judgment module; The first judgment module is used to judge whether the third peak of the trap distribution curve in the trap distribution condition is greater than a preset peak value, and when judging that the third peak value is less than or equal to the preset peak value, prompt the second judgment module to judge whether the carrier mobility is greater than the preset mobility.

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