A method, device and equipment for predicting the insulation aging life of high-voltage AC cables

Abstract

The present invention relates to the technical field of high-voltage AC cable insulation, and provides a method, device and equipment for predicting the insulation aging life of high-voltage AC cables, including: obtaining the electrothermal data of a cable sample and the cable breakdown time; the electrothermal data includes the effective voltage value and temperature of the cable sample; according to the cable breakdown time of the cable sample, calculating the characteristic breakdown time corresponding to the cable sample by using the Weibull distribution; establishing an electrothermal composite field cable insulation aging life prediction model with the electrothermal data and characteristic breakdown time of the cable sample; obtaining the electrothermal data of the cable to be predicted under the actual application environment, and calculating the insulation aging life of the cable to be predicted by using the prediction model, which can efficiently and accurately predict the life of the cable under the corresponding electrothermal composite field.

Description

Technical Field

[0001] The present invention relates to the technical field of high-voltage AC cable insulation, and particularly to a method, device and equipment for predicting the insulation aging life of high-voltage AC cables. Background Art

[0002] In recent years, the proportion of electricity in terminal energy consumption has been continuously increasing, and high-voltage AC cable transmission has become a key means for urban power grid transformation, capacity expansion and new energy grid connection. However, while the power consumption load of the urban power grid is continuously increasing, the operating temperature of high-voltage AC cables is also rising continuously. The insulation of high-voltage AC cables is more likely to undergo insulation aging and deterioration under the action of the electro-thermal composite field. Therefore, the key to ensuring the safe and reliable operation of high-voltage AC cables is to predict their insulation aging life under the action of the electro-thermal composite field.

[0003] Scholars at home and abroad have proposed some empirical models based on the insulation aging characteristics to reflect the aging law of insulation materials, such as the inverse power model, exponential model, Arrhenius model, RAMU model, etc. However, the above models also show significant deficiencies in the application process. For example, the inverse power model and Arrhenius model can only describe the aging process under the action of a single factor of electric field and thermal field. When the electro-thermal factors are applied to the insulation material simultaneously, the aging life time is significantly shortened, resulting in the inability of the inverse power model and Arrhenius model to accurately describe the actual life of high-voltage AC cable insulation; the background of the RAMU model is based on the inverse power function law of classical single-stress electrical aging, and the constant of the inverse power function law is set as a parameter related to temperature, so as to describe the combined influence of electric field and temperature on the insulation aging life. However, this model has a large evaluation error and a small applicable range, and it is difficult to accurately evaluate the insulation aging life of high-voltage AC cables. Summary of the Invention

[0004] The present invention provides a method for predicting the insulation aging life of high-voltage AC cables, which is used to solve the problem of inaccurate evaluation of the life of high-voltage AC cables in the prior art.

[0005] The first aspect of the present invention provides a method for predicting the insulation aging life of high-voltage AC cables, including:

[0006] Obtaining the electro-thermal data of the cable sample and the cable breakdown time; the electro-thermal data includes the effective voltage value and temperature of the cable sample;

[0007] Calculating the characteristic breakdown time corresponding to the cable sample according to the cable breakdown time of the cable sample by using the Weibull distribution;

[0008] Establishing an electro-thermal composite field cable insulation aging life prediction model based on the electro-thermal data and characteristic breakdown time of the cable sample;

[0009] Obtain the electrothermal data of the cable to be predicted in the actual application environment, and calculate the insulation aging life of the cable to be predicted with the prediction model.

[0010] Optionally, according to the cable breakdown time of the cable sample, calculate the characteristic breakdown time corresponding to each group of cable samples with the Weibull distribution. Specifically: Fit the cable breakdown time in the cable sample to obtain the corresponding Weibull distribution model. The Weibull distribution model is:

[0011]

[0012] where P is the breakdown probability, α is the scale parameter of the breakdown time, β is the shape parameter of the breakdown time, and t is the breakdown time;

[0013] According to the preset breakdown probability, obtain the characteristic breakdown time corresponding to the cable sample with the Weibull distribution model.

[0014] Optionally, establish an electrothermal composite field cable insulation aging life parameter model with the electrothermal data and characteristic breakdown time of the cable sample. Specifically:

[0015] Substitute the electrothermal data and characteristic breakdown time of n groups of cable samples into the electrothermal composite field cable insulation aging life parameter model in pairs respectively, and calculate the values of δ, λ and ; n is an integer not less than 3, and the electrothermal data of each group are different;

[0016] The electrothermal composite field cable insulation aging life parameter model is specifically:

[0017]

[0018] where t 1 、U 1 and T 1 are the characteristic breakdown time, effective voltage value and temperature of a group of cable samples respectively, t 2 、U 2 and T 2 are the characteristic breakdown time, effective voltage value and temperature of another group of cable samples respectively, E bd is the characteristic breakdown field strength of the cable sample that has been aged, E bd0 is the characteristic breakdown field strength of the cable sample that has not been aged, λ is the first electrothermal coefficient, δ is the second electrothermal coefficient, is the electrothermal error parameter;

[0019] Establish the electrothermal composite field cable insulation aging life prediction model with the values of δ, λ and .

[0020] Optionally, the electrothermal composite field cable insulation aging life prediction model is specifically as follows:

[0021]

[0022] where t 0 is the predicted cable insulation aging life, U 0 is the effective voltage value of the cable to be predicted, and T 0 is the temperature where the cable to be predicted is located.

[0023] Optionally, the ratio of E bd to E bd0 in the formula is determined according to a preset threshold for judging the end of the cable life.

[0024] Optionally, if the cable sample has the same size as the cable to be predicted, then according to the electric field strength of the electric field where the cable sample is located and the electric field strength of the actual application environment of the cable to be predicted, the ratio of U 1 to U 0 in the formula is determined.

[0025] Optionally, the electrothermal data of the cable sample is measured according to the electrothermal composite field where the cable sample is located;

[0026] The electrothermal composite field is an oil bath environment with an electric field set, where the value range of the oil bath temperature is 50 - 150 °C, and the value range of the electric field strength is 40 - 80 kV / mm.

[0027] Optionally, the electric field of the electrothermal composite field is arranged with columnar electrodes, and the value range of the chamfer radius of the columnar electrodes is 0.5 - 1 mm.

[0028] The second aspect of the present application provides a device for measuring the insulation aging life of a high-voltage AC cable under an electrothermal composite field, including:

[0029] A cable sample experiment module for obtaining the electrothermal data and the cable breakdown time of the cable sample; the electrothermal data includes the effective voltage value and the temperature of the cable sample;

[0030] A characteristic breakdown time calculation module for calculating the characteristic breakdown time corresponding to the cable sample according to the cable breakdown time of the cable sample with Weibull distribution;

[0031] A cable insulation aging life prediction model establishment module for establishing an electrothermal composite field cable insulation aging life prediction model with the electrothermal data and the characteristic breakdown time of the cable sample;

[0032] A cable insulation aging life prediction module for obtaining the electrothermal data of the cable to be predicted in the actual application environment and calculating the insulation aging life of the cable to be predicted with the prediction model.

[0033] A third aspect of the present application provides a device for measuring the insulation aging life of a high-voltage AC cable under an electrothermal composite field. The device includes a processor and a memory:

[0034] The memory is used to store program code and transmit the program code to the processor;

[0035] The processor is used to execute the method for measuring the insulation aging life of a high-voltage AC cable under an electrothermal composite field according to any one of the instructions in the program code of the first aspect of the present invention.

[0036] It can be seen from the above technical solutions that the present invention has the following advantages: By obtaining the electrothermal data of the cable sample and the cable breakdown time; the electrothermal data includes the effective voltage value and temperature of the cable sample; according to the cable breakdown time of the cable sample, the characteristic breakdown time corresponding to the cable sample is calculated by Weibull distribution; based on the electrothermal data and the characteristic breakdown time of the cable sample, an electrothermal composite field cable insulation aging life prediction model is established; according to the effective voltage value of the cable to be predicted and the temperature of the electrothermal composite field where it is located, the insulation aging life of the cable to be predicted is calculated by the prediction model. The characteristic breakdown time calculated by Weibull distribution describes the characteristics of the cable under the electrothermal field, and the life prediction model reflects the variation law of the insulation aging life of the cable under the combined action of voltage and temperature, and can efficiently and accurately predict the life of the cable under the corresponding electrothermal composite field. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order 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 following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0038] Figure 1 It is a flowchart of a method for predicting the insulation aging life of a high-voltage AC cable;

[0039] Figure 2 It is a flowchart for calculating the characteristic breakdown time of a method for predicting the insulation aging life of a high-voltage AC cable;

[0040] Figure 3 It is a flowchart for establishing a prediction model of a method for predicting the insulation aging life of a high-voltage AC cable;

[0041] Figure 4 It is a flowchart of an electrothermal field experiment of a method for predicting the insulation aging life of a high-voltage AC cable;

[0042] Figure 5 It is a general flowchart of a method for predicting the insulation aging life of a high-voltage AC cable;

[0043] Figure 6 It is a diagram of a device for predicting the insulation aging life of high-voltage AC cables. Specific implementation manners

[0044] In order to make the invention objectives, features, and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below 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 making creative efforts belong to the scope of protection of the present invention.

[0045] The present invention provides a method for predicting the insulation aging life of high-voltage AC cables, which is used to solve the problem of inaccurate life assessment of high-voltage AC cables in the prior art.

[0046] Please refer to Figure 1 , Figure 1 , which is a flowchart of the method for predicting the insulation aging life of high-voltage AC cables provided by the embodiment of the present invention.

[0047] S100. Obtain the electrothermal data of the cable sample and the cable breakdown time; the electrothermal data includes the effective voltage value and temperature of the cable sample;

[0048] It should be noted that in this embodiment, the cable sample is first placed in an electrothermal composite field, and at the same time, the electric field strength and temperature of the electrothermal composite field are controlled to be constant at a preset value. The effective voltage value and temperature of the cable sample are obtained, and then the cable breakdown time required for the cable sample to be broken down in the electrothermal composite field is recorded. The effective voltage value is calculated according to the field strength of the AC electric field and the size of the cable, and the cable breakdown time refers to the time elapsed when the degree of insulation failure of the cable sample reaches the preset value in the experiment.

[0049] S200. Calculate the characteristic breakdown time corresponding to the cable sample according to the cable breakdown time of the cable sample with Weibull distribution;

[0050] It should be noted that the cable breakdown time of the cable sample is fitted into a two-parameter Weibull distribution curve, and the characteristic breakdown time corresponding to the electrothermal data of this group of cable samples is obtained with Weibull distribution.

[0051] S300. Establish an electrothermal composite field cable insulation aging life prediction model with the electrothermal data and characteristic breakdown time of the cable sample;

[0052] It should be noted that in this embodiment, the characteristic breakdown times obtained when the cable sample is under the simultaneous action of voltage and temperature are combined to establish a prediction model for the insulation aging life of the cable in the electro-thermal composite field, which reflects the relationship among the three.

[0053] S400. Obtain the electro-thermal data of the cable to be predicted in the actual application environment, and calculate the insulation aging life of the cable to be predicted with the prediction model.

[0054] It should be noted that since the prediction model for the insulation aging life of the cable in the electro-thermal composite field reflects the influence of voltage and temperature on the aging life, substituting the effective value of the voltage and the temperature at which the cable to be predicted is located into it for calculation can obtain the corresponding insulation aging life.

[0055] In this embodiment, first, the characteristic breakdown time of the cable sample is calculated using the Weibull distribution. Then, a prediction model for the insulation aging life of the cable in the electro-thermal composite field is established. Finally, the electro-thermal data of the cable to be predicted are substituted to calculate its insulation aging life. The characteristic breakdown time calculated by the Weibull distribution describes the characteristics of the cable under the electro-thermal field. The life prediction model reflects the variation law of the insulation aging life of the cable under the combined action of voltage and temperature, and can efficiently and accurately predict the life of the cable under the corresponding electro-thermal composite field.

[0056] The above is the detailed description of the first embodiment of a method for predicting the insulation aging life of a high-voltage AC cable provided by this application. The following is the detailed description of the second embodiment of a method for predicting the insulation aging life of a high-voltage AC cable provided by this application.

[0057] Refer to Figure 2 , Figure 2 which is the flow chart for calculating the characteristic breakdown time of the method for predicting the insulation aging life of a high-voltage AC cable. In step S200 of the foregoing embodiment, when calculating the characteristic breakdown time corresponding to the cable sample according to the cable breakdown time of the cable sample using the Weibull distribution, specifically:

[0058] S210. Fit the cable breakdown times in the cable sample to obtain the corresponding Weibull distribution model.

[0059] It should be noted that the Weibull distribution model is:

[0060]

[0061] Wherein, P is the breakdown probability, α is the scale parameter of the breakdown time, β is the shape parameter of the breakdown time, and t is the breakdown time; the number of samples in each group of cable samples is 5 - 10. The breakdown times of multiple cables in the same group are fitted to a two-parameter Weibull distribution to obtain the scale parameter α of the breakdown time and the shape parameter β of the breakdown time, and a Weibull distribution model corresponding to this group of cable samples is obtained.

[0062] Further, in this embodiment, the number of samples in each group of cable samples being 5 - 10 improves the efficiency of Weibull distribution fitting. In actual prediction experiments, the number of samples in each group of cable samples can be selected to be more than 10. The more the number of cables in each group of cable samples, the more the number of breakdown times obtained for fitting, and the more accurate the Weibull distribution obtained by fitting.

[0063] S220, according to the preset breakdown probability, obtain the characteristic breakdown time corresponding to the cable sample using the Weibull distribution model.

[0064] It should be noted that, in this embodiment, the preset breakdown probability is 63.2%, and this value corresponds to the average life of the cable, that is, the mathematical expectation of the cable life in the Weibull distribution.

[0065] Refer to Figure 3 , Figure 3 For the flow chart of establishing the prediction model of the high-voltage AC cable insulation aging life prediction method; in step S300 of the foregoing embodiment, establishing the electro-thermal composite field cable insulation aging life prediction model using the electro-thermal data and characteristic breakdown time of the cable sample specifically includes:

[0066] S310, establish an electro-thermal composite field cable insulation aging life parameter model;

[0067] The electro-thermal composite field cable insulation aging life parameter model specifically includes:

[0068]

[0069] Wherein, t 1 , U 1 and T 1 are respectively the characteristic breakdown time, the effective voltage value, and the temperature of a group of cable samples, t 2 , U 2 and T 2 are respectively the characteristic breakdown time, the effective voltage value, and the temperature of another group of cable samples, E bd is the characteristic breakdown field strength of the cable sample that has aged, E bd0 is the characteristic breakdown field strength of the cable sample that has not aged, λ is the first electro-thermal coefficient, δ is the second electro-thermal coefficient, is the electrothermal error parameter. "Aged" refers to the state when the cable aging reaches a preset level, while "unaged" refers to the state when the cable has not started to age.

[0070] S320. Substitute the electrothermal data and characteristic breakdown time of n groups of cable samples into the electrothermal composite field cable insulation aging life parameter model in pairs, and calculate the values of δ, λ, and ;

[0071] It should be noted that n is an integer not less than 3, and the electrothermal data of each group are different. The difference in electrothermal data means that it can be only the effective voltage or the temperature that is different, or both the effective voltage and the temperature are different. To ensure that the three unknown values of δ, λ, and can be calculated, at least 3 groups of electrothermal data are required in this embodiment. In actual prediction calculations, more groups of electrothermal data can further optimize the data in the life parameter model and prediction model, making the finally predicted life more accurate.

[0072] S330. Establish the electrothermal composite field cable insulation aging life prediction model with the values of δ, λ, and ;

[0073] It should be noted that the electrothermal composite field cable insulation aging life prediction model is specifically as follows:

[0074]

[0075] where t 0 is the predicted cable insulation aging life, U 0 is the effective voltage of the cable to be predicted, and T 0 is the temperature where the cable to be predicted is located. After substituting the values of δ, λ, and , it is also necessary to substitute the electrothermal data and corresponding characteristic breakdown time of any group of cable samples.

[0076] Furthermore, the ratio of E bd to E bd0 does not need to be calculated, but can be directly determined according to the preset threshold for judging the end of the cable life and substituted into the formula.

[0077] It should be noted that in this embodiment, when the cable insulation characteristic breakdown field strength E bd is reduced to half of the characteristic breakdown field strength E bd0 of the insulation sample before aging, it is regarded that the insulation of the high-voltage AC cable reaches the end of its life, that is, the ratio of E bd to E bd0The ratio takes a value of 1 / 2. Similarly, this value can also be taken in the life parameter model of step S310. During the entire life prediction process, the preset threshold for determining the end of the cable's life should be consistent. After multiple experiments, a value of 1 / 2 is a more suitable value for the threshold, and in actual prediction experiments, this ratio can be adjusted according to requirements.

[0078] Further, for the calculation of the effective value of the alternating current voltage, in this embodiment, if the cable sample has the same size as the cable to be predicted, then according to the electric field intensity of the electric field where the cable sample is located and the electric field intensity of the actual application environment of the cable to be predicted, determine U in the formula 1 and U 0 ratio.

[0079] It should be noted that although the effective value of the cable voltage is proportional to the electric field intensity where the cable is located, the specific value needs to be calculated according to the alternating current electric field intensity where the cable is located and the size of the cable. When the thickness of the cable is the same, the ratio of the effective values of the voltages of the cables is equal to the ratio of the electric field intensities of the electric fields where they are located. There is no need to accurately calculate the effective value of the voltage, and the maximum electric field intensity set in the electrothermal composite field can be directly substituted. The ratio of the maximum electric field intensities of the electrothermal composite fields where two groups of cable samples are located is used to replace the effective values of the voltages of the two groups of cable samples.

[0080] The finally obtained electrothermal composite field cable insulation aging life prediction model is specifically as follows:

[0081]

[0082] Among them, E 1 is the maximum electric field intensity of any group of cable samples substituted above in the electrothermal composite field, and E 0 is the maximum electric field intensity of the electrothermal composite field where the cable to be predicted is located

[0083] In this embodiment, the characteristic breakdown time of the cable sample is calculated through the Weibull distribution, then an electrothermal composite field cable insulation aging life prediction model is established, and finally the electrothermal data of the cable to be predicted are substituted to calculate its insulation aging life. The characteristic breakdown time calculated by the Weibull distribution describes the characteristics of the cable under the electrothermal field. The life prediction model reflects the change law of the cable insulation aging life under the joint action of voltage and temperature, optimizes the model calculation, and can efficiently and accurately predict the life of the cable under the corresponding electrothermal composite field.

[0084] The above is the detailed description of the second embodiment of a high-voltage AC cable insulation aging life prediction method provided by this application. The following is the detailed description of the third embodiment of a high-voltage AC cable insulation aging life prediction method provided by this application.

[0085] Refer toFigure 4 , Figure 4 is the experimental flowchart of the electro-thermal field for the method of predicting the insulation aging life of high-voltage AC cables; in step S100 of the foregoing embodiment, obtaining the electro-thermal data and the cable breakdown time of the cable sample; the electro-thermal data includes the effective voltage value and temperature of the cable sample, and specifically further includes:

[0086] S110, using a flat vulcanizer to prepare a high-voltage AC cable sample, the temperature and pressure of insulation cross-linking, simulating the manufacturing process of the high-voltage AC cable, and removing cross-linking by-products after the manufacturing is completed.

[0087] It should be noted that the cable sample obtained in this embodiment is to simulate the cable to be predicted through a flat vulcanizer, and a flat sample is made of the insulating material of the cable to be predicted, which is convenient for obtaining electro-thermal data and cable breakdown time, as well as for subsequent life prediction. In actual prediction, the electro-thermal data and cable breakdown time can also be measured using the same cable entity as the cable to be predicted. In this embodiment, the cross-linking temperature set by the flat vulcanizer is 180 °C, the pressure is 15 MPa, the manufacturing process lasts for 15 min, and the diameter of the prepared cable sample is 50 mm. After the manufacturing is completed, the cable sample is then placed in a 60 °C vacuum drying oven and left standing for more than 24 h to remove cross-linking by-products.

[0088] S120: Place the cable sample and the experimental electrode in the oil bath circulation for a preset time;

[0089] The electrode uses a columnar electrode, and the value range of its chamfer radius is 0.5 - 1 mm. In this embodiment, the electrode used is a columnar electrode made of brass with a diameter of 25 mm and a chamfer radius of 1 mm;

[0090] Furthermore, the value range of the oil bath temperature is 50 - 150 °C. In this embodiment, 3 groups of cable samples are respectively placed in 3 groups of oil bath circulations, and the 3 groups of oil bath temperatures are 70 °C, 105 °C, and 120 °C. Before the experiment starts, the oil bath circulation is turned on for more than 1 hour to make the electrode and the sample reach a constant experimental temperature, and at the same time, the gas adsorbed on the surface of the electrode and the insulating sample is removed.

[0091] S130: Apply a constant electric field to the cable samples in different groups in the oil bath environment until the cable samples are broken down; measure the electro-thermal data of the cable samples and record the cable breakdown time.

[0092] It should be noted that in this embodiment, the number of groups of cable samples is not less than 5. The cable breakdown specifically means that the insulation of the cable sample ages to a preset degree. In this embodiment, when the insulation ability of the cable sample ages to half of the insulation ability of the cable sample before aging, that is, when the characteristic breakdown field strength of the cable insulation decreases to half of the characteristic breakdown field strength of the insulation sample before aging, it is regarded that the cable sample is broken down.

[0093] The value range of the electric field strength is 40 - 80 kV / mm. The temperatures corresponding to the 3 groups of oil bath environments are 70°C at 80 kV / mm, 105°C at 75 kV / mm, and 120°C at 70 kV / mm respectively. It should be noted that the measurement of the effective voltage value in the electrothermal data is measured and calculated according to the electric field strength of the alternating current electric field where the cable sample is located and the size of the cable sample. In the subsequent calculation steps, the electric field strength is used for substitution, so there is no need to calculate the exact effective voltage value.

[0094] According to the description in the foregoing step S200, based on the cable breakdown time of the cable sample, the characteristic breakdown time corresponding to the cable sample is calculated using the Weibull distribution. It can be obtained that the characteristic breakdown time corresponding to the cable sample in the 70°C 80 kV / mm group is 63.1 h, the characteristic breakdown time corresponding to the cable sample in the 105°C 75 kV / mm group is 908.4 h, and the characteristic breakdown time corresponding to the cable sample in the 120°C 70 kV / mm group is 1499.4 h.

[0095] According to the description in the foregoing step S320, the electrothermal data and characteristic breakdown time of n groups of cable samples are respectively substituted into the electrothermal composite field cable insulation aging life parameter model in pairs to calculate the values of δ, λ, and The value of λ is 1.216×10 4 , is approximately equal to -1, and δ is -0.734×10 3 。

[0096] Based on the values of δ, λ, and a life prediction model is established. Then, according to the description in the foregoing step S400, the electrothermal data of the cable to be predicted in the actual application environment is obtained, and the insulation aging life of the cable to be predicted is calculated using the prediction model. Take the working electric field strength E 0 of the cable to be predicted is approximately 16 kV / mm, and the operating temperature in the electrothermal composite field is 90°C. The calculated insulation aging life of the high-voltage AC cable is 241,400 hours, approximately equal to 27.5 years.

[0097] Furthermore, please refer to Figure 5 , Figure 5 which is the overall flowchart of the high-voltage AC cable insulation aging life prediction method. Figure 5 The step content in

[0098] In this embodiment, after processing multiple groups of cable samples, they are placed in different electro-thermal composite fields to establish an electro-thermal composite field for the cable samples. The breakdown time of the cable is measured, providing data for model calculation in subsequent steps. This data reflects the variation law of the insulation aging life of the cable under the combined action of voltage and temperature, and can efficiently and accurately predict the life of the cable under the corresponding electro-thermal composite field.

[0099] The above is the detailed description of the third embodiment of a method for measuring the insulation aging life of high-voltage AC cables provided by this application. Next is the detailed description of a device for measuring the insulation aging life of high-voltage AC cables provided by the second aspect of this application.

[0100] Please refer to Figure 6 , Figure 6 which is a diagram of a device for predicting the insulation aging life of high-voltage AC cables. This embodiment provides a device for measuring the insulation aging life of high-voltage AC cables under an electro-thermal composite field, including:

[0101] A cable sample experiment module 10 for obtaining the electro-thermal data of the cable sample and the breakdown time of the cable; the electro-thermal data includes the effective voltage value and temperature of the cable sample.

[0102] A characteristic breakdown time calculation module 20 for calculating the characteristic breakdown time corresponding to the cable sample according to the breakdown time of the cable sample using the Weibull distribution.

[0103] A cable insulation aging life prediction model establishment module 30 for establishing a prediction model for the insulation aging life of the cable under the electro-thermal composite field using the electro-thermal data and characteristic breakdown time of the cable sample.

[0104] A cable insulation aging life prediction module 40 for obtaining the electro-thermal data of the cable to be predicted in the actual application environment and calculating the insulation aging life of the cable to be predicted using the prediction model.

[0105] The third aspect of this application also provides a device for measuring the insulation aging life of high-voltage AC cables, including a processor and a memory: the memory is used to store program code and transmit the program code to the processor; the processor is used to execute the above method for measuring the insulation aging life of high-voltage AC cables under the electro-thermal composite field according to the instructions in the program code.

[0106] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the above-described device and equipment can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated here.

[0107] In several embodiments provided by the present application, 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. In actual implementation, there may be other division methods. 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 coupling, direct coupling, or communication connection between each other can be through some interfaces, and the indirect coupling or communication connection of the device or unit can be in electrical, mechanical, or other forms.

[0108] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed to 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.

[0109] In addition, each functional unit in various embodiments of the present invention can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0110] 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 this 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 can 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: USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical disks, and other various media that can store program codes.

[0111] As mentioned above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; 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 described 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 predicting the insulation aging life of high-voltage AC cables, characterized in that, it includes: Obtaining the electrothermal data and the cable breakdown time of the cable sample; The electrothermal data includes the effective voltage and temperature of the cable sample; According to the cable breakdown time of the cable sample, calculating the characteristic breakdown time corresponding to the cable sample by Weibull distribution; Based on the electrothermal data and the characteristic breakdown time of the cable sample, establishing a prediction model for the insulation aging life of the electrothermal composite field cable; Obtaining the electrothermal data of the cable to be predicted in the actual application environment, and calculating the insulation aging life of the cable to be predicted with the prediction model; The establishing of the prediction model for the insulation aging life of the electrothermal composite field cable based on the electrothermal data and the characteristic breakdown time of the cable sample is specifically as follows: Establishing a parameter model for the insulation aging life of the electrothermal composite field cable; the parameter model for the insulation aging life of the electrothermal composite field cable is specifically as follows: Among them, t 1 , U 1 and T 1 are respectively the characteristic breakdown time, the effective voltage value and the temperature of a group of cable samples, t 2 , U 2 and T 2 are respectively the characteristic breakdown time, the effective voltage value and the temperature of another group of cable samples, E bd is the characteristic breakdown field strength of the aged cable sample, E bd0 is the characteristic breakdown field strength of the unaged cable sample, λ is the first electro-thermal coefficient, δ is the second electro-thermal coefficient, is the electro-thermal error parameter; Substitute the electrothermal data and characteristic breakdown time of n groups of cable samples into the electrothermal composite field cable insulation aging life parameter model in pairs, and calculate the values of δ, λ and ; where n is an integer not less than 3, and the electrothermal data of each group are different; Using δ, λ and to establish the prediction model for the aging life of the cable insulation in the electro-thermal composite field; the prediction model for the aging life of the cable insulation in the electro-thermal composite field is specifically as follows: Among them, t 0 is the predicted aging life of the cable insulation, U 0 is the effective voltage value of the cable to be predicted, T 0 is the temperature where the cable to be predicted is located.

2. A method for predicting the insulation aging life of high-voltage AC cables according to claim 1, characterized in that, The calculating of the characteristic breakdown time corresponding to each group of cable samples by Weibull distribution according to the cable breakdown time of the cable sample is specifically as follows: Fitting the cable breakdown time in the cable sample to obtain the corresponding Weibull distribution model, and the Weibull distribution model is: where P is the breakdown probability, α is the scale parameter of the breakdown time, β is the shape parameter of the breakdown time, and t is the breakdown time; According to the preset breakdown probability, obtaining the characteristic breakdown time corresponding to the cable sample with the Weibull distribution model.

3. A method for predicting the insulation aging life of high-voltage AC cables according to claim 1, characterized in that, Determine the ratio of E in the formula according to the preset threshold for judging that the cable reaches the end of its life bd and E bd0 .

4. A method for predicting the insulation aging life of high-voltage AC cables according to claim 1, characterized in that, If the dimensions of the cable sample are the same as those of the cable to be predicted, then the ratio of U in the formula is determined according to the electric field strength of the electric field where the cable sample is located and the electric field strength of the actual application environment of the cable to be predicted. 1 and U 0 in the ratio.

5. A method for predicting the insulation aging life of high-voltage AC cables according to claim 1, characterized in that, Calculating the electrothermal data of the cable sample according to the electrothermal composite field where the cable sample is located; The electrothermal composite field is an oil bath environment with an electric field set, where the value range of the oil bath temperature is 50 - 150 °C, and the value range of the electric field strength is 40 - 80 kV / mm.

6. The method for predicting the insulation aging life of high-voltage AC cables according to claim 5, characterized in that, The electric field of the electrothermal composite field is arranged with columnar electrodes, and the value range of the chamfer radius of the columnar electrodes is 0.5 - 1 mm.

7. A device for measuring the insulation aging life of high-voltage AC cables under an electrothermal composite field, characterized in that, it includes: A cable sample experiment module for obtaining the electrothermal data and the cable breakdown time of the cable sample; The electrothermal data includes the effective voltage and temperature of the cable sample; A characteristic breakdown time calculation module for calculating the characteristic breakdown time corresponding to the cable sample by Weibull distribution according to the cable breakdown time of the cable sample; A cable insulation aging life prediction model establishment module for establishing a prediction model for the insulation aging life of the electrothermal composite field cable based on the electrothermal data and the characteristic breakdown time of the cable sample; The cable insulation aging life prediction module is used to obtain the electrothermal data of the cable to be predicted in the actual application environment, and calculate the insulation aging life of the cable to be predicted with the prediction model; The cable insulation aging life prediction model establishment module is specifically used for: Establishing a cable insulation aging life parameter model for the electrothermal composite field; The cable insulation aging life parameter model for the electrothermal composite field is specifically: Among them, t 1 , U 1 and T 1 are respectively the characteristic breakdown time, the effective voltage value, and the temperature of a group of cable samples, t 2 , U 2 and T 2 are respectively the characteristic breakdown time, the effective voltage value, and the temperature of another group of cable samples, E bd is the characteristic breakdown field strength of the aged cable sample, E bd0 is the characteristic breakdown field strength of the unaged cable sample, λ is the first electrothermal coefficient, δ is the second electrothermal coefficient, is the electrothermal error parameter; Substitute the electrothermal data and characteristic breakdown times of n groups of cable samples into the electrothermal composite field cable insulation aging life parameter model in pairs, and calculate the values of δ, λ, and ; where n is an integer not less than 3, and the electrothermal data of each group are different; Using δ, λ, and values to establish the prediction model for the aging life of the cable insulation in the electro-thermal composite field; the prediction model for the aging life of the cable insulation in the electro-thermal composite field is as follows: where t 0 is the predicted aging life of the cable insulation, U 0 is the effective voltage value of the cable to be predicted, T 0 is the temperature where the cable to be predicted is located.

8. A measuring device for the insulation aging life of a high-voltage AC cable under an electrothermal composite field, 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 used to execute the method for measuring the insulation aging life of a high-voltage AC cable under an electrothermal composite field according to any one of claims 1-6 based on the instructions in the program codes.

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