Method and device for evaluating insulating property of alternating-current polypropylene cable under impulse voltage

Abstract

The invention discloses a method and a device for evaluating the insulating property of an alternating-current polypropylene cable under impulse voltage, which are used for solving the technical problem that the insulating property of the alternating-current polypropylene cable under the impulse voltage is not evaluated at present. The method comprises the following steps: acquiring a cable slice of an alternating current polypropylene cable; obtaining polypropylene probabilistic breakdown field strength of the cable slice based on a lifting method test; according to the polypropylene probabilistic breakdown field strength, a service life model used for carrying out service life prediction on the alternating current polypropylene cable is constructed in combination with accumulated breakdown tests under multiple impulse voltages; and carrying out a dielectric property test on the cable slices by combining an accumulated loss test under multiple impulse voltages, and constructing an aging model for evaluating the insulating property parameters of the alternating-current polypropylene cable.

Description

Technical Field

[0001] The present invention relates to the technical field of cable material performance evaluation, and particularly relates to a method for evaluating the insulation performance of an AC polypropylene cable under impulse voltage, a device for evaluating the insulation performance of an AC polypropylene cable under impulse voltage, an electronic device, and a storage medium. Background Art

[0002] As the main medium for electric energy transmission in the power system, power cables play a crucial role in the power system. Nowadays, with the continuous increase of the transmission voltage level, the power system has higher and higher requirements for the insulation materials of power cables.

[0003] During long-term operation, due to factors such as conductor heating and environmental heat, the insulation materials of power cables generally operate at a certain temperature level. The currently widely used cross-linked polyethylene (XLPE) power cables generally have a maximum operating temperature of 90°C. Its maximum operating temperature is lower than that of polypropylene (PP) power cables (110°C). Therefore, polypropylene cables have the advantage of higher operating temperatures compared to cross-linked polyethylene cables, which is beneficial for improving their current-carrying capacity. Moreover, cross-linked by-products are easily formed during the production process of cross-linked polyethylene cables, which affects the insulation performance. At the same time, the cross-linked polyethylene cable materials are difficult to recycle after service, which does not meet the requirements of today's environmentally friendly power cables. In summary, polypropylene has become one of the new environmentally friendly power cable insulation material choices to replace cross-linked polyethylene. Therefore, research on the dielectric properties and aging characteristics of polypropylene insulation materials has gradually attracted the attention of researchers.

[0004] Under the action of long-term power frequency electrical stress during long-term operation, the insulation material will inevitably deteriorate to a certain extent. This phenomenon is regarded as the electrical aging process of the cable during long-term operation. Currently, the life model of the insulation material under long-term electrical stress is mainly described by the inverse power model. Through this model, the life of the insulation material at a certain electric field strength can be quantitatively calculated. However, in actual situations, in addition to being subjected to the action of conventional long-term power frequency electrical stress during long-term actual operation of power cables, due to the existence of lightning, resonance, and switching overvoltages, in some cases, power cables will also be affected by impulse voltage. For the AC polypropylene high-voltage cables operating in the actual power system, it is necessary to evaluate their performance under multiple external impulse voltages. Currently, there is no complete method for evaluating the insulation performance of AC polypropylene cables under impulse voltage. Summary of the Invention

[0005] The present invention provides a method for evaluating the insulation performance of an AC polypropylene cable under impulse voltage, an apparatus for evaluating the insulation performance of an AC polypropylene cable under impulse voltage, an electronic device, and a storage medium, which are used to solve or partially solve the technical problem that there is currently no method for evaluating the insulation performance of an AC polypropylene cable under impulse voltage.

[0006] The present invention provides a method for evaluating the insulation performance of an AC polypropylene cable under impulse voltage, and the method includes:

[0007] Obtain a cable slice of the AC polypropylene cable;

[0008] Based on the up-and-down method test, obtain the probability breakdown field strength of polypropylene of the cable slice;

[0009] According to the probability breakdown field strength of polypropylene, combine the cumulative breakdown test under multiple impulse voltages to construct a life model; the life model is used to predict the life of the AC polypropylene cable;

[0010] Combine the cumulative loss test under multiple impulse voltages to perform dielectric property testing on the cable slice, and construct an aging model; the aging model is used to evaluate the insulation performance parameters of the AC polypropylene cable.

[0011] Optionally, the obtaining the probability breakdown field strength of polypropylene of the cable slice based on the up-and-down method test includes:

[0012] Obtain voltage level data;

[0013] According to the voltage level data, perform a breakdown test on the cable slice with voltage up-and-down adjustment to obtain the breakdown probability and the breakdown voltage at the breakdown probability;

[0014] Calculate the breakdown field strength at the breakdown probability according to the breakdown voltage, and use it as the probability breakdown field strength of polypropylene of the cable slice.

[0015] Optionally, the voltage level data includes several voltage levels with equal pressure difference increments; the performing a breakdown test on the cable slice with voltage up-and-down adjustment according to the voltage level data to obtain the breakdown probability and the breakdown voltage at the breakdown probability includes:

[0016] Step S1: Select a target voltage level in ascending order of voltage level;

[0017] Step S2: Apply the breakdown test voltages corresponding to the target voltage level to the cable slice successively;

[0018] Step S3: Determine whether breakdown occurs during the voltage application process; if not, select the next voltage level of the current target voltage level as the new target voltage level, and jump to execute Step S2; if so, select the previous voltage level of the current target voltage level as the new target voltage level, and jump to execute Step S2;

[0019] Step S4: When the breakdown tests for all voltage levels are completed, calculate the breakdown probability and the breakdown voltage at the breakdown probability based on the breakdown test results.

[0020] Optionally, the constructing a life model by combining the cumulative breakdown tests under multiple impulse voltages based on the probabilistic breakdown field strength of the polypropylene includes:

[0021] Taking the probabilistic breakdown field strength of the polypropylene as a reference, conduct cumulative breakdown tests on the cable slice under multiple impulse voltages to obtain the U-N characteristic curve between the impulse voltage amplitude U and the impulse voltage number N;

[0022] Based on the U-N characteristic curve, perform linear fitting to obtain the life model of the AC polypropylene cable under different impulse voltages.

[0023] Optionally, the taking the probabilistic breakdown field strength of the polypropylene as a reference, conducting cumulative breakdown tests on the cable slice under multiple impulse voltages to obtain the U-N characteristic curve between the impulse voltage amplitude U and the impulse voltage number N includes:

[0024] Taking the probabilistic breakdown field strength of the polypropylene as a reference, based on the breakdown voltage, determine multiple impulse voltage amplitudes U for stepwise voltage reduction with a preset voltage drop amplitude;

[0025] For each impulse voltage amplitude U, repeatedly apply the impulse voltage amplitude U to the cable slice until the cable slice breaks down, and record the impulse voltage number N;

[0026] Based on each impulse voltage amplitude U and its corresponding impulse voltage number N, plot the U-N characteristic curve between the impulse voltage amplitude U and the impulse voltage number N.

[0027] Optionally, the dielectric performance test of the cable slice by combining the cumulative loss tests under multiple impulse voltages to construct an aging model includes:

[0028] Conduct cumulative breakdown tests on the cable slice under multiple impulse voltages to obtain the dielectric performance parameters of the AC polypropylene cable after being subjected to different numbers of impulse voltages; the dielectric performance parameters are used to evaluate the cumulative loss effect of multiple impulse voltages on the AC polypropylene cable;

[0029] Construct an aging model of the AC polypropylene cable under different impulse voltages according to the dielectric property parameters.

[0030] Optionally, the dielectric property parameters include the breakdown field strength after the action of the impulse voltage, the steady-state conductance current, the isothermal relaxation depolarization current, and the maximum value of the space charge density; the constructing of the aging model of the AC polypropylene cable under different impulse voltages according to the dielectric property parameters includes:

[0031] Construct a power-frequency breakdown field strength model according to the impulse voltage amplitude, the number of impulse voltages, and the breakdown field strength; the power-frequency breakdown field strength model is used to evaluate the remaining breakdown field strength of the AC polypropylene cable after the impulse voltage.

[0032] Construct a conductance current model according to the impulse voltage amplitude, the number of impulse voltages, and the steady-state conductance current; the conductance current model is used to evaluate the conductance characteristics of the AC polypropylene cable after the impulse voltage.

[0033] Calculate the insulation material life index after the action of the impulse voltage based on the fitting result of the isothermal relaxation depolarization current, and construct an aging degree evaluation model according to the impulse voltage amplitude, the number of impulse voltages, and the insulation material life index; the aging degree evaluation model is used to evaluate the aging degree of the AC polypropylene cable after the impulse voltage.

[0034] Construct a space charge model according to the impulse voltage amplitude, the number of impulse voltages, and the maximum value of the space charge density; the space charge model is used to evaluate the space charge characteristics of the AC polypropylene cable after the impulse voltage.

[0035] Integrate the power-frequency breakdown field strength model, the conductance current model, the aging degree evaluation model, and the space charge model as the aging model of the AC polypropylene cable under different impulse voltages.

[0036] The present invention also provides an insulation performance evaluation device for an AC polypropylene cable under an impulse voltage, including:

[0037] A cable slice acquisition unit for acquiring cable slices of the AC polypropylene cable.

[0038] A staircase method test unit for obtaining the probability breakdown field strength of the polypropylene of the cable slice based on the staircase method test.

[0039] A life model construction unit for constructing a life model according to the probability breakdown field strength of the polypropylene and combining the cumulative breakdown test under multiple impulse voltages; the life model is used to predict the life of the AC polypropylene cable.

[0040] An aging model construction unit is configured to perform dielectric property tests on the cable slice by combining cumulative loss tests under multiple impulse voltages, and construct an aging model; the aging model is used to evaluate insulation performance parameters of the AC polypropylene cable.

[0041] The present invention also provides an electronic device, which includes a processor and a memory:

[0042] The memory is used to store program codes and transmit the program codes to the processor;

[0043] The processor is configured to execute the insulation performance evaluation method of the AC polypropylene cable under impulse voltage as described in any one of the above according to the instructions in the program codes.

[0044] The present invention also provides a computer-readable storage medium, which is used to store program codes, and the program codes are used to execute the insulation performance evaluation method of the AC polypropylene cable under impulse voltage as described in any one of the above.

[0045] It can be seen from the above technical solutions that the present invention has the following advantages:

[0046] An insulation performance evaluation method of an AC polypropylene cable under impulse voltage is provided. First, a cable slice of the AC polypropylene cable is obtained, so that the actual cable slice of the AC polypropylene cable can be directly used as the research object, which can make the evaluation result more reliable; then, the polypropylene probabilistic breakdown field strength of the cable slice is obtained based on the up-and-down method test; then, according to the polypropylene probabilistic breakdown field strength, combined with the cumulative breakdown test under multiple impulse voltages, a life model for predicting the life of the AC polypropylene cable is constructed; at the same time, dielectric property tests are performed on the cable slice by combining cumulative loss tests under multiple impulse voltages, and an aging model for evaluating insulation performance parameters of the AC polypropylene cable is constructed. Thus, the probabilistic breakdown field strength is obtained through the up-and-down method test, and a life model of the AC polypropylene insulating material is obtained through the cumulative breakdown test of multiple impulse voltages. At the same time, a cumulative loss characteristic model is constructed as an aging model of the polypropylene insulating material under the cumulative action of impulse voltages through the measured dielectric property parameters after multiple impulse voltages to characterize the influence of multiple impulse voltages on the performance of the insulating material. By paying attention to the actual operating state and insulation performance degradation status of the power cable after impulse voltage, a complete description of the breakdown characteristics, cumulative loss characteristics and life model of polypropylene under impulse voltage is provided, which has guiding significance for the state evaluation of power cables in actual operation after bearing corresponding impulses. Description of the Drawings

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0048] Figure 1 It is a schematic diagram of a cable slice of an AC polypropylene cable;

[0049] Figure 2 It is a flowchart of the steps of a method for evaluating the insulation performance of an AC polypropylene cable under impulse voltage;

[0050] Figure 3 It is a schematic diagram of a typical impulse voltage waveform;

[0051] Figure 4 It is a schematic diagram of a common circuit for impulse voltage;

[0052] Figure 5 It is a schematic diagram of a multi-stage impulse voltage generator;

[0053] Figure 6 It is a schematic diagram of measuring the breakdown field strength of probabilistic impulse voltage by the up-and-down method;

[0054] Figure 7 It is a schematic diagram of the U-N characteristic curve of a polypropylene insulating material;

[0055] Figure 8 It is a schematic diagram of the overall process of a method for evaluating the insulation performance of an AC polypropylene cable under impulse voltage;

[0056] Figure 9 It is a structural block diagram of a device for evaluating the insulation performance of an AC polypropylene cable under impulse voltage. Specific embodiments

[0057] The embodiments of the present invention provide a method for evaluating the insulation performance of an AC polypropylene cable under impulse voltage, a device for evaluating the insulation performance of an AC polypropylene cable under impulse voltage, an electronic device, and a storage medium, which are used to solve or partially solve the technical problem that there is currently no technical solution for evaluating the insulation performance of an AC polypropylene cable under impulse voltage.

[0058] In order to make the object, features, and advantages of the present invention more obvious and understandable, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described below are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0059] As an example, taking the insulation material of AC polypropylene cable as an example, under the action of power frequency electrical stress during long-term operation, the insulation material will inevitably deteriorate to a certain extent. This phenomenon is regarded as the electrical aging process of the cable during long-term operation. Currently, the life model of the insulation material under long-term electrical stress is mainly described by the inverse power model. Through this model, the life of the insulation material at a certain electric field strength can be quantitatively calculated.

[0060] However, in actual situations, in addition to being subjected to the action of conventional long-term power frequency electrical stress during long-term actual operation of power cables, due to the existence of lightning, resonance, and switching overvoltages, in some cases, power cables will also be affected by impulse voltages. For the AC polypropylene high-voltage cables operating in the actual power system, it is necessary to evaluate their performance under multiple external impulse voltages. Currently, there is no complete method for evaluating the insulation performance of AC polypropylene cables under impulse voltages.

[0061] Through further analysis, the present invention believes that the evaluation of the insulation performance and life model of AC polypropylene insulation materials under impulse voltages mainly includes the following aspects.

[0062] (1) The probabilistic breakdown field strength of AC polypropylene insulation materials under impulse voltages

[0063] Due to the special nature of impulse voltages, the breakdown characteristics of insulation materials are generally described by the probabilistic breakdown field strength. Currently, the most widely used is the 50% impulse breakdown field strength. That is, at this impulse voltage amplitude, there is a 50% probability that the insulation material will be broken down. For insulation materials in different positions and for different uses, there should be corresponding breakdown field strengths. For example, for the insulation materials of key parts, it is required to leave more margins in the design. At this time, it is more appropriate to use the 10% breakdown field strength or a lower probability of breakdown field strength. For the insulation materials of non-critical parts, the 90% breakdown field strength may also meet the system requirements.

[0064] (2) The breakdown characteristics of polypropylene insulation materials under multiple impulse voltages

[0065] During the actual operation process, the probability of insulation breakdown caused by a single impulse voltage is relatively small. The breakdown of the insulating material by applying impulse voltage mainly results from the cumulative effect of multiple impulse voltages. Therefore, it is also necessary to consider the breakdown characteristics of AC polypropylene insulating materials under the cumulative effect of multiple impulse voltages. The main objective of this process is to obtain the U-N characteristic curve between the impulse voltage amplitude U and the number of times N required for breakdown. Through this curve, the life model of AC polypropylene under impulse voltage can be further obtained.

[0066] (III) Cumulative loss characteristics of polypropylene insulating materials under multiple impulse voltages

[0067] Even if the long-term impulse voltage cannot directly break down the insulating material, its cumulative loss to the insulating material will gradually make it inapplicable for long-term operation in the power system. The impacts of long-term impulse voltage on insulating materials include but are not limited to the deterioration of its own performance, the decline in the ability to withstand long-term electrical stress, etc. Therefore, it is also necessary to evaluate the cumulative loss characteristics of AC polypropylene insulating materials under multiple impulse voltages.

[0068] Therefore, one of the core inventive points of the embodiments of the present invention lies in: fully considering the operating characteristics of AC polypropylene materials under impulse voltage, and proposing an insulation performance evaluation method for AC polypropylene cables under impulse voltage. Taking the actual cable slices of AC polypropylene cables as the research object, the probabilistic breakdown field strength is obtained through the up-and-down method test, and the life model of AC polypropylene insulating materials is obtained through the cumulative breakdown test of multiple impulse voltages. At the same time, based on the dielectric performance parameters measured after multiple impulse voltages, a cumulative loss characteristic model is constructed as the aging model of polypropylene insulating materials under the cumulative effect of impulse voltage to characterize the impact of multiple impulse voltages on the performance of insulating materials. The present invention mainly focuses on the actual operating state and insulation performance deterioration of power cables after being subjected to impulse voltage. The proposed solution can completely describe the breakdown characteristics, cumulative loss characteristics and life model of polypropylene under impulse voltage, thus having guiding significance for the state evaluation of power cables in actual operation after withstanding corresponding impulses.

[0069] The embodiments of the present invention provide a set of annular cable slicing devices. Different thicknesses of cable slice specimens can be cut along the circumferential direction of the cable through the annular cable slicing device. Compared with the commonly used parallel slicing, the schematic diagram of the cable slices of the AC polypropylene cable provided by the embodiments of the present invention is as Figure 1 shown, and the specific schematic diagram of the annular slicing method can be referred to r4.

[0070] After cutting the cable slice at the required research position, the probability breakdown field strength can be tested subsequently. Then, based on the obtained impulse voltage breakdown field strength, by reducing the voltage amplitude, the U-N characteristic curve between the impulse voltage amplitude U and the number of impulse voltages N required to break down the cable slice specimen is obtained, and the lifetime model is further obtained through curve fitting. Through various dielectric property evaluation methods, such as power frequency breakdown test, conduction current test, space charge test, isothermal relaxation current test, etc., the insulation performance of the AC polypropylene cable under multiple impulse voltages is evaluated.

[0071] Refer to Figure 2 , which shows the step flow chart of a method for evaluating the insulation performance of an AC polypropylene cable under impulse voltage provided by an embodiment of the present invention, and specifically may include the following steps:

[0072] Step 201, obtain a cable slice of the AC polypropylene cable;

[0073] First, cable slices at different positions of the AC polypropylene cable can be obtained through an annular cable slicing device. Among them, the specific required slice position can be set according to actual research needs.

[0074] Step 202, obtain the polypropylene probability breakdown field strength of the cable slice based on the up-and-down method test;

[0075] In this step, mainly through the up-and-down method test, the polypropylene probability breakdown field strength (including the 50% impulse breakdown field strength with the widest applicable scenario) is obtained. By obtaining the breakdown field strength of the AC polypropylene cable at multiple probabilities, the impulse breakdown characteristics of the insulating material can be comprehensively evaluated.

[0076] Exemplarily, Figure 3 shows a schematic diagram of a typical impulse voltage waveform.

[0077] Figure 3 In is the front time, defined as the horizontal coordinate distance between the straight line passing through and and the abscissa of the intersection of the zero point and the peak value. is the tail time, defined as the horizontal coordinate distance between the zero point and the half-peak value. The impulse voltage waveform can be described using a double-exponential waveform, as shown in the following formula:

[0078]

[0079] Wherein, represents the voltage value at time t; represents the peak voltage; , both represent exponential fitting coefficients.

[0080] Figure 4 Shows a schematic diagram of a common circuit for impulse voltage. Through calculation, the relationship between resistance and capacitance and the wavefront and wave-tail times can be obtained as follows:

[0081]

[0082]

[0083] In practical applications, the impulse voltage waveform can be changed by changing the resistance and capacitance. Those skilled in the art can change the corresponding parameters according to their own test requirements. It can be understood that the present invention does not limit this.

[0084] When a higher impulse voltage needs to be generated, it can be achieved through Figure 5 the multi-stage impulse voltage generator shown. The multi-stage impulse voltage generator mainly uses the principle of "series charging and parallel discharging" to generate high-amplitude impulse voltage.

[0085] During the charging process, the spark gap is not broken down, so in the charging circuit, this branch is considered open. At this time, each stage of capacitor C is charged in parallel through charging resistors R with different numbers by a power supply with a voltage of . During the discharging process, once the first gap F1 is broken down, the gaps F2, F3, etc. of each stage are broken down in turn. The series connection of each stage of capacitors causes the generator to change from the charging state to the discharging state. During the discharging process, due to the relatively large resistance values of the charging resistors R of each stage, the resistance branch can be simplified to an open circuit during the short discharging process.

[0086] According to the above analysis, during the discharging process, the voltages on all parallel capacitors are released in series form, and a relatively high instantaneous high voltage can be formed.

[0087] In some embodiments, based on the process of obtaining the probabilistic breakdown field strength of the polypropylene of the cable slice through the up-and-down method test, it can be achieved by performing the following sub-steps 2021 to 2023:

[0088] Step 2021: Obtain voltage level data;

[0089] Step 2022: Conduct a breakdown test on the cable slice based on voltage up-and-down adjustment according to the voltage level data, and obtain the breakdown probability and the breakdown voltage at the breakdown probability;

[0090] Further, the voltage level data includes several voltage levels increasing with equal voltage differences. Then, the process of conducting a breakdown test on the cable slice based on voltage up-and-down adjustment according to the voltage level data and obtaining the breakdown probability and the breakdown voltage at the breakdown probability can be achieved by performing the following sub-steps S1 to S4:

[0091] Step S1: Select a target voltage level in ascending order of voltage levels;

[0092] Step S2: Apply the breakdown test voltages corresponding to the target voltage level to the cable slices successively;

[0093] Step S3: Determine whether a breakdown phenomenon occurs during the voltage application process; if not, select the next voltage level of the current target voltage level as the new target voltage level, and jump to execute Step S2; if so, select the previous voltage level of the current target voltage level as the new target voltage level, and jump to execute Step S2;

[0094] Step S4: When the breakdown tests for all voltage levels are completed, calculate the breakdown probability and the breakdown voltage at the breakdown probability according to the breakdown test results.

[0095] Step 2023: Calculate the breakdown electric field at the breakdown probability according to the breakdown voltage, which is used as the polypropylene probabilistic breakdown electric field of the cable slice.

[0096] In practical applications, for the up-and-down method test introduced in the previous steps, assume that there are m groups of applied voltage levels, and each group contains n constant voltages. During the up-and-down test, if no breakdown phenomenon occurs in any of the n voltage applications corresponding to the current voltage level, then on the basis of the current voltage level add a voltage difference , and use as the next voltage level and continue to perform the breakdown test. If a breakdown phenomenon occurs in any of the n voltage applications corresponding to the current voltage level , then reduce the corresponding voltage, that is, reduce a voltage difference , to obtain the previous voltage level , and continue to perform the breakdown test. Through several groups of breakdown tests, the probabilistic breakdown voltage can be obtained as shown in the following formula:

[0097]

[0098] In the formula, is the number of groups of applied voltages at voltage , and m is the total number of groups.

[0099] The breakdown probability of the probabilistic breakdown voltage can then be calculated by the following formula:

[0100]

[0101] It can be clearly seen from the above formula that when the number of pressurization times n = 1 for each group, the 50% impulse breakdown voltage of the insulating material is obtained at this time.

[0102] It can be understood that those skilled in the art can adjust the rising and falling method test parameters according to different requirements to obtain the breakdown field strength at different probabilities (such as 50%, 10%, 90%, etc.). Exemplarily, Figure 6 Fig. shows a schematic diagram of measuring the breakdown field strength of a probabilistic impulse voltage by the rising and falling method. What is calculated in this process is the 50% impulse breakdown voltage.

[0103] Step 203, construct a life model according to the probabilistic breakdown field strength of the polypropylene, in combination with the cumulative breakdown test under multiple impulse voltages; the life model is used for predicting the life of the AC polypropylene cable;

[0104] In a specific implementation, constructing a life model according to the probabilistic breakdown field strength of polypropylene, in combination with the cumulative breakdown test under multiple impulse voltages, can be: taking the probabilistic breakdown field strength of polypropylene as a reference, conducting a cumulative breakdown test on the cable slice under multiple impulse voltages to obtain the U-N characteristic curve between the impulse voltage amplitude U and the impulse voltage number N; performing linear fitting based on the U-N characteristic curve to obtain the life model of the AC polypropylene cable under different impulse voltages.

[0105] In some embodiments, the process of taking the probabilistic breakdown field strength of polypropylene as a reference, conducting a cumulative breakdown test on the cable slice under multiple impulse voltages, and obtaining the U-N characteristic curve between the impulse voltage amplitude U and the impulse voltage number N can be implemented by performing the following sub-steps 2031 to 2033:

[0106] Step 2031: Taking the probabilistic breakdown field strength of polypropylene as a reference, determine multiple impulse voltage amplitudes U for stepwise voltage reduction with a preset voltage drop amplitude according to the breakdown voltage;

[0107] Step 2032: For each impulse voltage amplitude U, repeatedly apply the impulse voltage amplitude U to the cable slice until the cable slice breaks down, and record the impulse voltage number N;

[0108] Step 2033: According to each impulse voltage amplitude U and its corresponding impulse voltage number N, draw the U-N characteristic curve between the impulse voltage amplitude U and the impulse voltage number N.

[0109] Specifically, to obtain the life model of the polypropylene insulating material under impulse voltage, taking the probabilistic breakdown field strength of polypropylene obtained by the previous steps as a reference, by continuously reducing the impulse voltage amplitude, such as setting the voltage difference of the impulse voltage amplitude to Through the cumulative effect of multiple impulse voltages, the U-N characteristic curve between the impulse voltage amplitude U and the number of impulse voltages N required to break down the cable slice specimen can be obtained. Then, by fitting the curve, the life model of the polypropylene insulating material under impulse voltage can be obtained. The U-N characteristic curve of the polypropylene insulating material is as Figure 7 shown.

[0110] Among them, an exponential model can be used to fit the U-N characteristic curve to obtain the life model of the AC polypropylene cable under different impulse voltages, as shown in the following formula:

[0111]

[0112] 1 represents the curve slope, represents the fitting exponent.

[0113] Through the above life model, the service life of the polypropylene insulating material under different impulse voltage amplitudes can be calculated.

[0114] Step 204: Combine the cumulative loss test under multiple impulse voltages to perform dielectric property testing on the cable slice, and construct an aging model; the aging model is used to evaluate the insulation performance parameters of the AC polypropylene cable.

[0115] In this step, mainly through a dielectric property testing system, the dielectric properties of the polypropylene insulating material after being subjected to different numbers of impulse voltages are measured, and the cumulative effect of multiple impulse voltages on the cable slice specimen is evaluated based on the measured parameters, and an aging model of the AC polypropylene cable under impulse voltage is constructed.

[0116] In a specific implementation, combining the cumulative breakdown test under multiple impulse voltages to perform dielectric property testing on the cable slice and construct an aging model can be as follows: First, perform a cumulative breakdown test on the cable slice under multiple impulse voltages to obtain the dielectric property parameters of the AC polypropylene cable after being subjected to different numbers of impulse voltages; among them, the dielectric property parameters are used to evaluate the cumulative loss effect of multiple impulse voltages on the AC polypropylene cable; then, based on the dielectric property parameters, an aging model of the AC polypropylene cable under different impulse voltages is constructed.

[0117] In some embodiments, the dielectric property parameters include the breakdown field strength, steady-state conduction current, isothermal relaxation depolarization current, and maximum space charge density after the action of the impulse voltage. Then, the process of constructing an aging model of the AC polypropylene cable under different impulse voltages based on the dielectric property parameters can be realized by performing the following sub-steps 2041 to 2045:

[0118] Step 2041: Construct a power-frequency breakdown field strength model based on the impulse voltage amplitude, the number of impulse voltages, and the breakdown field strength; the power-frequency breakdown field strength model is used to evaluate the remaining breakdown field strength of the AC polypropylene cable after impulse voltage application;

[0119] For the breakdown field strength test, a functional relationship between the number of impulse voltages N, the impulse voltage amplitude U, and the breakdown field strength E after the application of the impulse voltage can be constructed as the power-frequency breakdown field strength model:

[0120]

[0121] The power-frequency breakdown field strength of the polypropylene insulating material after impulse voltage application can be quantitatively calculated through the power-frequency breakdown field strength model. If the calculated breakdown field strength value is less than the system requirement, replacement should be considered.

[0122] Step 2042: Construct a conductance current model based on the impulse voltage amplitude, the number of impulse voltages, and the steady-state conductance current; the conductance current model is used to evaluate the conductance characteristics of the AC polypropylene cable after impulse voltage application;

[0123] For the conductance current test, a functional relationship between the number of impulse voltages N, the impulse voltage amplitude U, and the steady-state conductance current after the application of the impulse voltage can be constructed as the conductance current model:

[0124]

[0125] Step 2043: Calculate the insulation material life index after impulse voltage application based on the fitting results of the isothermal relaxation depolarization current, and construct an aging degree evaluation model based on the impulse voltage amplitude, the number of impulse voltages, and the insulation material life index; the aging degree evaluation model is used to evaluate the aging degree of the AC polypropylene cable after impulse voltage application;

[0126] For the isothermal relaxation current test, first, the isothermal relaxation depolarization current can be fitted through the following three-exponential model:

[0127]

[0128] Among them, the morphology of the cable slice specimen shows a coexistence form of spherulites and amorphous. Its relaxation mechanism can be divided into three types: (1) The macroscopic relaxation formed by the specimen and the electrode. Although AC polypropylene is a weakly polar medium, there is a shift in the charge center on the side chains and end groups of its molecules, and it still exhibits certain dipole characteristics externally. Therefore, there is dipole polarization in AC polypropylene. Reflected in macroscopic polarization, it is the polarization mechanism formed by the electrode and the medium. (2) Considering that the morphology of the cable slice specimen is in the form of spherulites and amorphous, there is an interface between the spherulites and the amorphous. Therefore, there is interfacial polarization between the spherulites and the amorphous, which is expressed as a polarization at the mesoscopic scale. (3) There may be some small molecule impurities in the polypropylene insulating material, and there are also interactions between these impurities and the molecules. In the above formula, and are related to the three relaxation mechanisms in the aforementioned AC polypropylene. is the relaxation time constant of the relevant relaxation mechanism, is the corresponding relaxation strength.

[0129] The insulation material life index can be calculated through the fitting results :

[0130]

[0131]

[0132]

[0133] Then, the functional relationship between the number of impulse voltages N, the impulse voltage amplitude U, and the insulation material life index after the impulse voltage can be constructed as an aging degree evaluation model:

[0134]

[0135] When the calculated value is greater than 2.1, it is considered that the polypropylene insulating material is severely aged. Through the aging degree evaluation model and combined with the actual operation conditions of the cable, the operation state of the AC polypropylene cable at this time can be qualitatively analyzed. If it reaches the severe aging degree, it should be considered to strengthen the detection and evaluation of this part of the cable, and even replace part of the cable.

[0136] Step 2044: Construct a space charge model according to the impulse voltage amplitude, the number of impulse voltages, and the maximum value of the space charge density; the space charge model is used to evaluate the space charge characteristics of the AC polypropylene cable after the impulse voltage;

[0137] For the space charge test, the number of impulse voltages N, the impulse voltage amplitude U, and the maximum value of the space charge density The functional relationship between them is used as the space charge model:

[0138]

[0139] The increase in space charge density may lead to an increase in the electric field strength inside the dielectric, thereby accelerating the aging process of the insulation material of AC polypropylene cables. If the calculated space charge density is large, the actual situation of this part of the cable during subsequent operation should be considered emphatically.

[0140] Step 2045: Integrate the power frequency breakdown field strength model, the conduction current model, the aging degree evaluation model, and the space charge model as the aging model of the AC polypropylene cable under different impulse voltages.

[0141] By integrating the power frequency breakdown field strength model, the conduction current model, the aging degree evaluation model, and the space charge model constructed in the foregoing steps, an aging model of the AC polypropylene cable under different impulse voltages can be obtained.

[0142] Thus, according to all the above relevant steps, the change trend of the insulation performance of the AC polypropylene insulation material under multiple impulse voltages can be comprehensively analyzed, which has certain guiding significance for the actual operation of power cables.

[0143] In the embodiment of the present invention, fully considering the operating characteristics of the AC polypropylene material under impulse voltage, an insulation performance evaluation method for an AC polypropylene cable under impulse voltage is proposed. Taking the actual cable section of the AC polypropylene cable as the research object, the probabilistic breakdown field strength is obtained through the up-and-down method test, and the life model of the AC polypropylene insulation material is obtained through the cumulative breakdown test of multiple impulse voltages. At the same time, through the dielectric performance parameters measured after multiple impulse voltages, a cumulative loss characteristic model is constructed as the aging model of the polypropylene insulation material under the cumulative action of impulse voltage to characterize the influence of multiple impulse voltages on the performance of the insulation material. The present invention mainly focuses on the actual operating state and insulation performance deterioration of the power cable after impulse voltage. The proposed solution can completely describe the breakdown characteristics, cumulative loss characteristics, and life model of the polypropylene under impulse voltage, thus having guiding significance for the state evaluation of power cables in actual operation after withstanding corresponding impulses.

[0144] For better illustration, refer to Figure 8 , which shows the overall flowchart of an insulation performance evaluation method for an AC polypropylene cable under impulse voltage provided by the embodiment of the present invention. It should be noted that this embodiment only briefly describes the general process of the insulation performance evaluation of the AC polypropylene cable under impulse voltage. The specific implementation process of each step can be understood by referring to the relevant content in the foregoing embodiments, and will not be elaborated here. It can be understood that the present invention places no restrictions on this.

[0145] Step 801: Obtain a cable slice of an AC polypropylene cable and voltage level data.

[0146] Step 802: Conduct a breakdown test on the cable slice based on voltage rise and fall adjustment according to the voltage level data, obtain the breakdown probability and the breakdown voltage at the breakdown probability, and calculate the breakdown field strength at the breakdown probability based on the breakdown voltage, which is used as the polypropylene probabilistic breakdown field strength of the cable slice.

[0147] Step 803: Taking the polypropylene probabilistic breakdown field strength as a benchmark, conduct a cumulative breakdown test on the cable slice under multiple impulse voltages, obtain the U-N characteristic curve between the impulse voltage amplitude U and the number of impulse voltages N, and perform linear fitting based on the U-N characteristic curve to obtain the life model of the AC polypropylene cable under different impulse voltages.

[0148] Step 804: Conduct a cumulative breakdown test on the cable slice under multiple impulse voltages, obtain the dielectric performance parameters of the AC polypropylene cable after being subjected to different numbers of impulse voltages, and construct an aging model of the AC polypropylene cable under different impulse voltages according to the dielectric performance parameters.

[0149] Step 805: Perform life prediction on the AC polypropylene cable based on the life model, and evaluate the insulation performance parameters of the AC polypropylene cable based on the aging model.

[0150] Refer to Figure 9 , which shows the structural block diagram of an insulation performance evaluation device for an AC polypropylene cable under impulse voltage provided by an embodiment of the present invention, and specifically may include:

[0151] A cable slice acquisition unit 901, configured to acquire a cable slice of an AC polypropylene cable.

[0152] A lift method test unit 902, configured to obtain the polypropylene probabilistic breakdown field strength of the cable slice based on the lift method test.

[0153] A life model construction unit 903, configured to construct a life model according to the polypropylene probabilistic breakdown field strength in combination with a cumulative breakdown test under multiple impulse voltages; the life model is used to perform life prediction on the AC polypropylene cable.

[0154] An aging model construction unit 904, configured to perform dielectric performance testing on the cable slice in combination with a cumulative loss test under multiple impulse voltages, and construct an aging model; the aging model is used to evaluate the insulation performance parameters of the AC polypropylene cable.

[0155] In an optional embodiment, the lift method test unit 902 includes:

[0156] A data acquisition unit for acquiring voltage level data;

[0157] A breakdown test unit for performing a breakdown test with voltage rise and fall adjustment on the cable slice according to the voltage level data to obtain a breakdown probability and a breakdown voltage at the breakdown probability;

[0158] A breakdown field strength calculation unit for calculating the breakdown field strength at the breakdown probability according to the breakdown voltage as the polypropylene probabilistic breakdown field strength of the cable slice.

[0159] In an alternative embodiment, the voltage level data includes a number of voltage levels increasing with equal voltage differences; the breakdown test unit includes:

[0160] A target voltage level selection unit for performing step S1: selecting a target voltage level in ascending order of voltage levels;

[0161] A multiple breakdown test voltage application unit for performing step S2: sequentially applying multiple breakdown test voltages corresponding to the target voltage level to the cable slice;

[0162] A voltage rise and fall execution unit for performing step S3: determining whether a breakdown phenomenon occurs during the voltage application; if not, selecting the next voltage level of the current target voltage level as the new target voltage level and jumping to execute step S2; if so, selecting the previous voltage level of the current target voltage level as the new target voltage level and jumping to execute step S2;

[0163] A breakdown voltage calculation unit for performing step S4: when the breakdown tests for all voltage levels are completed, calculating the breakdown probability and the breakdown voltage at the breakdown probability according to the breakdown test results.

[0164] In an alternative embodiment, the life model construction unit 903 includes:

[0165] A U-N characteristic curve construction unit for performing cumulative breakdown tests on the cable slice under multiple impulse voltages based on the polypropylene probabilistic breakdown field strength to obtain a U-N characteristic curve between the impulse voltage amplitude U and the impulse voltage number N;

[0166] A linear fitting unit for performing linear fitting based on the U-N characteristic curve to obtain the life model of the AC polypropylene cable under different impulse voltages.

[0167] In an alternative embodiment, the U-N characteristic curve construction unit includes:

[0168] An impulse voltage amplitude determination unit, configured to determine a plurality of impulse voltage amplitudes U for stepwise voltage reduction with a preset voltage drop amplitude based on the probability breakdown field strength of the polypropylene and according to the breakdown voltage.

[0169] An impulse voltage amplitude application unit, configured to repeatedly apply the impulse voltage amplitude U to the cable slice for each of the impulse voltage amplitudes U until a breakdown phenomenon occurs in the cable slice, and record the number of impulse voltages N.

[0170] A characteristic curve plotting unit, configured to plot a U-N characteristic curve between the impulse voltage amplitude U and the number of impulse voltages N based on each of the impulse voltage amplitudes U and their corresponding numbers of impulse voltages N.

[0171] In an alternative embodiment, the aging model construction unit 904 includes:

[0172] A dielectric property parameter measurement unit, configured to perform a cumulative breakdown test on the cable slice under multiple impulse voltages to obtain the dielectric property parameters of the AC polypropylene cable after being subjected to different numbers of impulse voltages; the dielectric property parameters are used to evaluate the cumulative loss effect of multiple impulse voltages on the AC polypropylene cable.

[0173] An aging model construction subunit, configured to construct an aging model of the AC polypropylene cable under different impulse voltages based on the dielectric property parameters.

[0174] In an alternative embodiment, the dielectric property parameters include the breakdown field strength, steady-state conductance current, isothermal relaxation depolarization current, and maximum space charge density after the action of the impulse voltage; the aging model construction subunit includes:

[0175] A power frequency breakdown field strength model construction unit, configured to construct a power frequency breakdown field strength model based on the impulse voltage amplitude, the number of impulse voltages, and the breakdown field strength; the power frequency breakdown field strength model is used to evaluate the remaining breakdown field strength of the AC polypropylene cable after the impulse voltage.

[0176] A conductance current model construction unit, configured to construct a conductance current model based on the impulse voltage amplitude, the number of impulse voltages, and the steady-state conductance current; the conductance current model is used to evaluate the conductance characteristics of the AC polypropylene cable after the impulse voltage.

[0177] An aging degree evaluation model construction unit, configured to calculate the insulation material life index after the action of the impulse voltage based on the fitting result of the isothermal relaxation depolarization current, and construct an aging degree evaluation model based on the impulse voltage amplitude, the number of impulse voltages, and the insulation material life index; the aging degree evaluation model is used to evaluate the aging degree of the AC polypropylene cable after the impulse voltage.

[0178] A space charge model construction unit for constructing a space charge model based on the impulse voltage amplitude, the number of impulse voltages, and the maximum value of the space charge density; the space charge model is used to evaluate the space charge characteristics of the AC polypropylene cable after the impulse voltage;

[0179] A model integration unit for integrating the power frequency breakdown field strength model, the conduction current model, the aging degree evaluation model, and the space charge model as the aging model of the AC polypropylene cable under different impulse voltages.

[0180] For the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple. For the relevant parts, refer to the corresponding description in the foregoing method embodiment.

[0181] The embodiment of the present invention also provides an electronic device, which includes a processor and a memory:

[0182] The memory is used to store program codes and transmit the program codes to the processor;

[0183] The processor is used to execute the method for evaluating the insulation performance of the AC polypropylene cable under impulse voltage according to the instructions in the program codes in any embodiment of the present invention.

[0184] The embodiment of the present invention also provides a computer-readable storage medium, which is used to store program codes, and the program codes are used to execute the method for evaluating the insulation performance of the AC polypropylene cable under impulse voltage in any embodiment of the present invention.

[0185] Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes of the above-described systems, devices, and units can refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated herein.

[0186] In several embodiments provided by the present invention, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there can be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of the devices or units can be in electrical, mechanical, or other forms.

[0187] The unit described as a separation component may or may not be physically separated. The component shown as a unit may or may not be a physical unit, that is, it may be located in one place or may be distributed across multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0188] In addition, each functional unit in various embodiments of the present invention may be integrated in a processing unit, may exist physically separately for each unit, or two or more units may be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0189] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs that can store program codes.

[0190] As mentioned above, the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of various embodiments of the present invention.

Claims

1. A method for evaluating the insulation performance of an AC polypropylene cable under impulse voltage, characterized in that, Including: Obtaining a cable slice of an AC polypropylene cable; Obtaining the probabilistic breakdown field strength of polypropylene of the cable slice based on the up-and-down method test; Constructing a life model according to the probabilistic breakdown field strength of polypropylene and combining with the cumulative breakdown test under multiple impulse voltages; the life model is used for predicting the life of the AC polypropylene cable; Conducting dielectric property tests on the cable slice by combining with the cumulative loss test under multiple impulse voltages, and constructing an aging model; the aging model is used for evaluating the insulation performance parameters of the AC polypropylene cable.

2. The insulation performance evaluation method according to claim 1, characterized in that The obtaining the probabilistic breakdown field strength of polypropylene of the cable slice based on the up-and-down method test includes: Obtaining voltage level data; Conducting a breakdown test on the cable slice based on voltage up-and-down adjustment according to the voltage level data, and obtaining the breakdown probability and the breakdown voltage at the breakdown probability; Calculating the breakdown field strength at the breakdown probability according to the breakdown voltage as the probabilistic breakdown field strength of polypropylene of the cable slice.

3. The insulation performance evaluation method according to claim 2, characterized in that The voltage level data includes several voltage levels increasing with equal voltage differences; the conducting a breakdown test on the cable slice based on voltage up-and-down adjustment according to the voltage level data, and obtaining the breakdown probability and the breakdown voltage at the breakdown probability includes: Step S1: Selecting a target voltage level in ascending order of voltage levels; Step S2: Successively applying the breakdown test voltages corresponding to the target voltage level to the cable slice; Step S3: Judging whether a breakdown phenomenon occurs during the voltage application process; if not, selecting the next voltage level of the current target voltage level as the new target voltage level, and jumping to execute Step S2; if so, selecting the previous voltage level of the current target voltage level as the new target voltage level, and jumping to execute Step S2; Step S4: When the breakdown tests of all voltage levels are completed, calculating the breakdown probability and the breakdown voltage at the breakdown probability according to the breakdown test results.

4. The insulation performance evaluation method according to claim 2, wherein The constructing a life model according to the probabilistic breakdown field strength of polypropylene and combining with the cumulative breakdown test under multiple impulse voltages includes: Taking the probabilistic breakdown field strength of polypropylene as a reference, conducting a cumulative breakdown test on the cable slice under multiple impulse voltages, and obtaining the U-N characteristic curve between the impulse voltage amplitude U and the impulse voltage number N; Performing linear fitting based on the U-N characteristic curve to obtain the life model of the AC polypropylene cable under different impulse voltages.

5. The insulation performance evaluation method according to claim 4, characterized in that The taking the probabilistic breakdown field strength of polypropylene as a reference, conducting a cumulative breakdown test on the cable slice under multiple impulse voltages, and obtaining the U-N characteristic curve between the impulse voltage amplitude U and the impulse voltage number N includes: Taking the probabilistic breakdown field strength of polypropylene as a reference, and determining multiple impulse voltage amplitudes U for stepwise voltage reduction with a preset voltage drop amplitude according to the breakdown voltage; For each impulse voltage amplitude U, repeatedly applying the impulse voltage amplitude U to the cable slice until the cable slice has a breakdown phenomenon, and recording the impulse voltage number N. According to each of the impulse voltage amplitudes U and their corresponding impulse voltage numbers N, a U-N characteristic curve between the impulse voltage amplitude U and the impulse voltage number N is plotted.

6. The insulation performance evaluation method according to claim 4 or 5, characterized in that, The dielectric performance test of the cable slice is combined with the cumulative loss test under multiple impulse voltages to construct an aging model, including: Performing a cumulative breakdown test on the cable slice under multiple impulse voltages to obtain the dielectric performance parameters of the AC polypropylene cable after being subjected to different numbers of impulse voltages; the dielectric performance parameters are used to evaluate the cumulative loss effect of multiple impulse voltages on the AC polypropylene cable; Construct an aging model of the AC polypropylene cable under different impulse voltages according to the dielectric performance parameters.

7. The insulation performance evaluation method according to claim 6, characterized in that The dielectric performance parameters include the breakdown field strength, steady-state conductance current, isothermal relaxation depolarization current, and maximum space charge density after the action of the impulse voltage; constructing the aging model of the AC polypropylene cable under different impulse voltages according to the dielectric performance parameters includes: Construct a power frequency breakdown field strength model according to the impulse voltage amplitude, the impulse voltage number, and the breakdown field strength; the power frequency breakdown field strength model is used to evaluate the remaining breakdown field strength of the AC polypropylene cable after the impulse voltage. Construct a conductance current model according to the impulse voltage amplitude, the impulse voltage number, and the steady-state conductance current; the conductance current model is used to evaluate the conductance characteristics of the AC polypropylene cable after the impulse voltage. Calculate the insulation material life index after the action of the impulse voltage based on the fitting result of the isothermal relaxation depolarization current, and construct an aging degree evaluation model according to the impulse voltage amplitude, the impulse voltage number, and the insulation material life index; the aging degree evaluation model is used to evaluate the aging degree of the AC polypropylene cable after the impulse voltage. Construct a space charge model according to the impulse voltage amplitude, the impulse voltage number, and the maximum space charge density; the space charge model is used to evaluate the space charge characteristics of the AC polypropylene cable after the impulse voltage. Integrate the power frequency breakdown field strength model, the conductance current model, the aging degree evaluation model, and the space charge model as the aging model of the AC polypropylene cable under different impulse voltages.

8. An insulation performance evaluation device for an AC polypropylene cable under impulse voltage, characterized in that, Including: A cable slice acquisition unit for acquiring a cable slice of an AC polypropylene cable; A step-up / step-down method test unit for obtaining the probability breakdown field strength of the polypropylene of the cable slice based on the step-up / step-down method test; A life model construction unit for constructing a life model according to the probability breakdown field strength of the polypropylene and combining the cumulative breakdown test under multiple impulse voltages; the life model is used to predict the life of the AC polypropylene cable; An aging model construction unit for performing dielectric performance tests on the cable slice in combination with the cumulative loss test under multiple impulse voltages to construct an aging model; the aging model is used to evaluate the insulation performance parameters of the AC polypropylene cable.

9. An electronic device, characterized in that, The device includes a processor and a memory: The memory is used to store program codes and transmit the program codes to the processor; The processor is configured to execute the method for evaluating the insulation performance of the AC polypropylene cable under impulse voltage according to any one of claims 1-7 based on the instructions in the program code.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium is configured to store program code, and the program code is used to execute the method for evaluating the insulation performance of the AC polypropylene cable under impulse voltage according to any one of claims 1-7.

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