Optimization method and device of cable terminal sleeve, electronic equipment and storage medium

Abstract

The invention discloses an optimization method and device of a cable terminal sleeve, electronic equipment and a storage medium. The method comprises the steps that a finite element model of the cable terminal sleeve is constructed, and electric-thermal coupling simulation of multiple conductivity parameters and multiple temperature working conditions is executed to obtain electric field intensity, temperature and current density distribution data under all the working conditions. Generating a first correlation curve based on the simulation data, and extracting a critical electric field value and a conduction coefficient slope through piecewise linear fitting; grouping the first correlation curves with the same conductivity to establish a second correlation curve, and calculating the linear attenuation rate as a temperature sensitivity index. Counting variances of the conduction coefficient at different temperatures to generate a conduction stability index; and combining the peak temperature data corresponding to each conductivity to construct a comprehensive heating evaluation model. By analyzing the relevance among the electric field attenuation characteristic, the conduction stability and the heat distribution index, a conductivity value optimal solution with the minimum heat distribution index is screened out. According to the invention, the overall performance of the cable terminal sleeve can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of cable design optimization, and particularly relates to an optimization method, device, electronic device and storage medium for a cable terminal bushing. Background Art

[0002] As a core insulation component of the high-voltage power transmission system, the performance of the cable terminal bushing directly affects the reliability of the power grid and the energy transmission efficiency. Under high temperature, strong electric field and complex working conditions, the bushing joint is prone to insulation deterioration or even breakdown due to local overheating, resulting in energy loss and safety hazards. Especially with the development of DC power transmission technology, overheating is likely to occur at the joint of the cable terminal bushing, which will accelerate aging and may even cause faults such as short circuits.

[0003] Although some current studies have preliminarily explored the electric field distribution, temperature field, etc. of the cable terminal bushing, the comprehensive research on the electrical insulation performance and thermal effect in the existing technology for the cable terminal bushing is still insufficient. The research mainly focuses on the analysis of the electric field distribution and insulation characteristics of the cable bushing. Although some studies have discussed the electric field distribution under different voltages, the influence of the electromagnetic-thermal coupling on the overall performance of the cable terminal bushing under complex working conditions has not been deeply considered. The changes in factors such as temperature and conductivity are often ignored, and the heating problem at the joint of the cable terminal bushing and its causes have not been comprehensively evaluated. Summary of the Invention

[0004] Embodiments of the present invention provide an optimization method, device, electronic device and storage medium for a cable terminal bushing. By implementing the present invention, the defect of the lack of comprehensive electromagnetic-thermal effect analysis in the optimization of the cable terminal bushing in the existing technology can be solved, thereby improving the overall performance of the cable terminal bushing.

[0005] An embodiment of the present invention provides an optimization method for a cable terminal bushing. A gasket is provided at the joint of the cable terminal bushing. The optimization method includes:

[0006] Obtaining a finite element model of the cable terminal bushing; wherein, the finite element model includes a simulated cable terminal bushing provided with a simulated gasket;

[0007] Based on the finite element model, performing electro-thermal coupling simulation on the simulated cable terminal bushing under multiple temperature conditions with different conductivities set for the simulated gasket, and generating electric field strength distribution data, simulated gasket temperature distribution data and current density distribution data of the simulated cable terminal bushing under different temperature conditions for each conductivity condition;

[0008] Based on the electric field strength distribution data and the current density distribution data, several first correlation curves corresponding to the simulated cable terminal bushing are generated, and a critical electric field value and a first slope corresponding to the first correlation curve are generated; wherein, each of the first correlation curves is used to characterize the relationship between the current density and the electric field strength under a certain conductivity and a certain temperature condition.

[0009] Group the first correlation curves with the same conductivity into one group to obtain several groups of first correlation curves; for each group of first correlation curves, extract the critical electric field values of the first correlation curves, and generate a second correlation curve for characterizing the relationship between the critical electric field value and the temperature under a certain conductivity according to the extracted critical electric field values and the temperatures corresponding to the first correlation curves; calculate the conduction stability index corresponding to each conductivity according to the first slopes of the first correlation curves in the first correlation curve group; determine the peak temperature of the simulated washer under each conductivity according to the simulated washer temperature distribution data.

[0010] Determine the optimized conductivity value of the washer according to the second correlation curves, conduction stability indices of each conductivity and the peak temperature of the simulated washer.

[0011] When the conductivity of the currently set washer is not the optimized conductivity value, select a corresponding washer according to the optimized conductivity value and replace the currently set washer.

[0012] Further, the obtaining of the finite element model of the cable terminal bushing includes:

[0013] Obtain the geometric parameters, material parameters and working condition parameters of the cable terminal bushing.

[0014] Construct a three-dimensional geometric model of the cable terminal bushing according to the geometric parameters.

[0015] Based on the Delaunay triangulation algorithm, perform mesh division on the three-dimensional geometric model to generate a meshed model of the cable terminal bushing.

[0016] Couple the material parameters and working condition parameters to the meshed model to generate a finite element model of the cable terminal bushing.

[0017] Further, the generating of several first correlation curves corresponding to the simulated cable terminal bushing according to the electric field strength distribution data and the current density distribution data, and generating a critical electric field value and a first slope corresponding to the first correlation curve includes:

[0018] Generate a first correlation curve for characterizing the relationship between the electric field strength and the current density under a certain conductivity and a certain temperature condition according to the electric field strength distribution data and the current density distribution data.

[0019] For each first correlation curve, perform piecewise linear fitting on the current first correlation curve to generate a linear fitting curve corresponding to the current first correlation curve; determine whether there is a break point in the current linear fitting curve. If so, use the slope of the last segment in the current linear fitting curve as the first slope corresponding to the current first correlation curve, and use the electric field strength value of the last break point as the critical electric field value corresponding to the current first correlation curve; if not, use the slope of the current linear fitting curve as the slope corresponding to the current first correlation curve, and use a preset electric field value as the critical electric field value corresponding to the current first correlation curve.

[0020] Further, calculating a conduction stability index corresponding to each conductivity according to the first slopes of the first correlation curves in the first correlation curve group includes:

[0021] For each correlation curve group, calculate the variance of the first slopes of the first correlation curves in the current correlation curve group as the conduction stability index corresponding to the current conductivity.

[0022] Further, determining the peak temperature of the simulation washer at each conductivity according to the simulation washer temperature distribution data includes:

[0023] Group the simulation washer temperature distribution data with the same conductivity into one group to obtain several groups of simulation washer temperature distribution data;

[0024] For each group of simulation washer temperature distribution data, extract the peak washer temperature of each simulation washer temperature distribution data; use the highest peak temperature as the peak temperature of the simulation washer at the current conductivity.

[0025] Further, determining the optimized conductivity value of the washer according to the second correlation curve, conduction stability index and peak temperature of each conductivity includes:

[0026] For each second correlation curve, perform least squares linear regression on the current second correlation curve within a preset temperature range to generate a fitting line for characterizing the relationship between the critical electric field value and temperature at a certain conductivity, and use the slope of the current fitting line as the critical electric field attenuation index of the current conductivity;

[0027] Determine the optimized conductivity value of the washer according to the critical electric field attenuation index, conduction stability index and peak temperature of each conductivity;

[0028] Calculate the comprehensive heating index of the simulation cable terminal bushing under each conductivity condition based on the peak temperature, the critical electric field attenuation index and the conduction stability index;

[0029] Take the conductivity corresponding to the lowest comprehensive heating index as the optimized value of the conductivity of the washer.

[0030] Furthermore, the comprehensive heating index is calculated by the following formula:

[0031] I(σ) = k1·T peak (σ) + k2·α(σ) + k3·Var(σ)

[0032] where, I(σ) is the comprehensive heating index corresponding to the conductivity σ; k1 is the weight coefficient of the peak temperature; k2 is the weight coefficient of the critical electric field attenuation index; k3 is the weight coefficient of the conduction stability index; T peak (σ) is the peak temperature of the conductivity σ; α(σ) is the critical electric field attenuation index of the conductivity σ; Var(σ) is the conduction stability index of the conductivity σ.

[0033] Based on the above method item embodiments, the present invention correspondingly provides device item embodiments.

[0034] An embodiment of the present invention provides an optimization device for a cable terminal bushing, including: a finite element model acquisition module, a multi-physical field coupling simulation module, a current density - electric field strength correlation modeling module, a critical electric field - temperature correlation analysis module, a conductivity optimized value decision module, and a conductivity adaptation optimization module;

[0035] The finite element model acquisition module is used to acquire the finite element model of the cable terminal bushing; wherein, the finite element model includes a simulated cable terminal bushing provided with a simulated washer;

[0036] The multi-physical field coupling simulation module is used to perform electro-thermal coupling simulation of the simulated cable terminal bushing under multiple temperature conditions for the simulated washer with different conductivities based on the finite element model, and generate electric field strength distribution data, simulated washer temperature distribution data, and current density distribution data of the simulated cable terminal bushing under different temperature conditions for each conductivity condition;

[0037] The first current density - electric field strength correlation modeling module is used to generate a number of first correlation curves corresponding to the simulated cable terminal bushing according to the electric field strength distribution data and the current density distribution data, and generate the critical electric field value and the first slope corresponding to the first correlation curve; wherein, each of the first correlation curves is used to characterize the relationship between the current density and the electric field strength under a conductivity and a temperature condition;

[0038] The critical electric field-temperature correlation analysis module is configured to group first correlation curves with the same conductivity into several groups of first correlation curves; for each group of first correlation curves, extract the critical electric field values of the first correlation curves, and generate a second correlation curve for characterizing the relationship between the critical electric field value and the temperature at a certain conductivity according to the extracted critical electric field values and the temperatures corresponding to the first correlation curves; calculate the conduction stability index corresponding to each conductivity according to the first slopes of the first correlation curves in the first correlation curve group; and determine the peak temperature of the simulation washer at each conductivity according to the simulation washer temperature distribution data.

[0039] The conductivity optimization value decision module is configured to determine the optimized conductivity value of the washer according to the second correlation curves of the conductivities, the conduction stability index, and the peak temperature of the simulation washer.

[0040] The conductivity adaptation and optimization module is configured to, when the currently set conductivity of the washer is not the optimized conductivity value, select a corresponding washer according to the optimized conductivity value and replace the currently set washer.

[0041] Based on the above method item embodiments, the present invention correspondingly provides an electronic device item embodiment.

[0042] An embodiment of the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the optimization method of the cable terminal sleeve described in any one of the above method item embodiments can be implemented.

[0043] Based on the above method item embodiments, the present invention correspondingly provides a storage medium item embodiment.

[0044] An embodiment of the present invention provides a storage medium, on which a computer program is stored. When the computer program is executed by a processor, the optimization method of the cable terminal sleeve described in any one of the above method item embodiments can be implemented.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] An embodiment of the present invention provides an optimization method, device, electronic device, and storage medium for a cable terminal sleeve. The method performs electro-thermal coupling simulation of multiple temperature conditions based on the model under different conductivity conditions, generates electric field strength, temperature, and current density distribution data; generates first correlation curves and their critical electric field values and slopes according to the data, extracts the critical electric field values to generate second correlation curves, and calculates the conduction stability index; determines the optimized conductivity according to the temperature distribution and the correlation curves, and replaces the washer according to this value.

[0047] The present invention generates a first correlation curve of the relationship between current density and electric field strength based on the data of electric field strength and current density distribution under different conductivity conditions, further fits the curve, extracts the critical electric field value and slope, and establishes a second correlation curve of the relationship between the critical electric field and temperature. According to the second correlation curve, combined with the changes in temperature and conductivity, the optimized conductivity value of the gasket is determined, solving the defect in the prior art that the optimization of cable terminal bushings lacks comprehensive electromagnetic-thermal effect analysis, thereby improving the overall performance of cable terminal bushings. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 FIG. is a schematic flow chart of an optimization method for a cable terminal bushing provided by an embodiment of the present invention.

[0049] Figure 2 FIG. is the overall structure of a cable terminal bushing provided by an embodiment of the present invention.

[0050] Figure 3 FIG. is the sectional structure of a cable terminal bushing provided by an embodiment of the present invention.

[0051] Figure 4 FIG. is the central cable structure of a cable terminal bushing provided by an embodiment of the present invention.

[0052] Figure 5 FIG. is a schematic structural diagram of an optimization device for a cable terminal bushing provided by an embodiment of the present invention.

[0053] DESCRIPTION OF THE REFERENCE NUMERALS:

[0054] 1. Connecting joint cable; 2. Wire changing terminal; 3. Nut; 4. D-shaped seal; 5. Gasket; 6. Rectangular sealing ring; 7. Conductive head; 8. High-voltage porcelain part; 9. Central cable; 10. Grounding end; 11. Conductive core; 12. Inner shield; 13. Main insulation; 14. Silicone oil; 15. Ceramic tube; 16. Reinforced insulation; 17. Stress cone; 18. Outer shield; 19. Cable outer shield; 20. Common point of main insulation, silicone oil and reinforced insulation; 21. Interface 1 of stress cone; 22. Interface 2 of stress cone; 23. Root of stress cone; 24. Front end of stress cone. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0055] 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 described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0056] As Figure 1As shown, an embodiment of the present invention provides an optimization method for a cable terminal bushing, where a gasket is provided at the joint of the cable terminal bushing; the optimization method at least includes the following steps:

[0057] Step S1: Obtain the finite element model of the cable terminal bushing.

[0058] Specifically, the finite element model includes a simulated cable terminal bushing provided with a simulated gasket.

[0059] In a preferred embodiment, the obtaining of the finite element model of the cable terminal bushing includes:

[0060] Obtain the geometric parameters, material parameters, and working condition parameters of the cable terminal bushing;

[0061] According to the geometric parameters, construct a three-dimensional geometric model of the cable terminal bushing;

[0062] Based on the Delaunay triangulation algorithm, perform mesh division on the three-dimensional geometric model to generate a meshed model of the cable terminal bushing;

[0063] Couple the material parameters and working condition parameters to the meshed model to generate the finite element model of the cable terminal bushing.

[0064] Specifically, first, through a high-precision three-dimensional scanner and material performance testing equipment, obtain the key geometric parameters of the cable terminal bushing (including structural dimensions such as core radius, shielding layer thickness, gasket installation gap, etc.), material parameters (nonlinear conductivity of the gasket, dielectric constant of the insulating layer, thermal conductivity, etc.), and working condition parameters (operating temperature range 30 - 70°C, voltage load ±500 kV, environmental humidity gradient, etc.). Based on the geometric parameters, use parametric modeling technology to construct a three-dimensional geometric solid model including the joint gasket structure in COMSOL Multiphysics to ensure that the geometric topology error from the real device is less than 0.1 mm.

[0065] Subsequently, perform non-uniform mesh division on the geometric model based on the Delaunay triangulation algorithm: Implement local mesh encryption in the high field strength concentration area (such as the gasket-insulating layer interface), with the mesh density reaching 3 times that of the adjacent area (element size ≤ 0.05 mm), and control the mesh transition ratio ≤ 1:3 to avoid distorted elements; use sparse meshes (element size 0.5 - 1 mm) in the low field strength area to reduce the calculation amount. The mesh quality is verified by the standard of the Jacobian determinant > 0.6, and finally a refined mesh model containing 500,000 to 1,000,000 elements is generated.

[0066] Finally, the material parameters are coupled to the grid cells in the form of a piecewise function, and the operating condition parameters are loaded as boundary conditions (such as the initial distribution of the temperature field and the amplitude of the voltage load). Through the strongly coupled iterative solution of the electromagnetic field control equations (Maxwell's equations) and the heat conduction equation, a finite element model that can accurately characterize the electro-thermal multi-physical field interaction is generated, providing a high-fidelity calculation basis for subsequent multi-condition simulations.

[0067] In one embodiment, according to the geometry and dimensions of the cable terminal joint, the COMSOL Multiphysics multi-physics modeling and simulation software is selected to model the HVDC (High Voltage Direct Current Transmission) cable terminal with a voltage level of ±500 kV for the cable bushing structure and the internal central cable respectively, as Figure 2 , 3 , shown in Figure 4, which mainly consists of structural components such as insulating high-voltage porcelain parts, protective covers, joint parts, and central cables. Figure 2 is the overall model structure of the terminal bushing, Figure 3 is the cross-sectional structure of the bushing, Figure 4 is the central cable structure, and the dimensions of each component of the central cable are shown in the following table:

[0068] Structure Dimensions / mm Core radius 19 Main insulation thickness 16 Reinforced insulation thickness 64 Shielding layer thickness 1 Axial length of stress cone 160

[0069] The entire length of the cable terminal model is specified as 2600 mm, and the convective heat transfer parameter of the surrounding air environment in this area is set to 10 W / (m2·K). The inner edge of the central cable with a DC high-voltage semi-conductive outer shield is grounded. The temperatures of the central cable and the ambient air domain are set to constant values of 70 °C and 30 °C respectively. Based on the physical drawing of the cable bushing, a three-dimensional geometric solid model of the cable bushing is established in this paper to study and analyze the electrical properties and temperature properties under the coupling of the electric field, electromagnetic field, and temperature field, and to observe the performance change characteristics under the environment of high temperature, strong electric field, and strong magnetic field, and whether it can ensure normal and stable operation under long-term carbonization.

[0070] The finite element model of the cable terminal bushing mainly explores the DC electrical properties of the simulated DC cable accessories under the coupled physical loads of the electrostatic field and heat transfer. Therefore, the relative permittivities of the outer shield layer of the cable bushing and the central cable under the DC electric field need to be set. The material properties of the parameters of each structural component of the cable bushing in this electro-thermal coupling simulation are shown in the following table:

[0071] Material Crosslinked polyethylene Inner shield Copper Aluminum Density 0.91 0.95 8.91 2.74 Relative permittivity 2.27 1e2 — — Thermal conductivity 1.64e3 2.5e3 400 238 Conductivity 1e-15 1.25e-2 5.96e7 3.77e7

[0072] Material Chrome-nickel steel Aluminum oxide ceramic Polyethylene copolymer resin Nitrile rubber Density 7.93 3.95 2.2 1.25 Relative permittivity — 11 2.1 4.5 Thermal conductivity 15.2 29.3 0.19 0.15 Conductivity 1.44e6 1.1e-16 4.13e-14~2.02e-12 1.3e-15

[0073] Among them, the unit of density is g·cm -3 , and the unit of thermal conductivity is W·m -1 ·K -1, the unit of conductivity is S / m.

[0074] Using the Delaunay (point set triangulation) algorithm, perform free triangular mesh generation on the geometric model. Select a very refined element size, and perform local mesh refinement in areas with large field strength changes to ensure sufficient accuracy in calculations. For example, use free triangular elements for finite element mesh generation with an element growth rate of 1.5 and narrow zone relaxation of 1.0, and further refine the areas with large changes in electric field strength and temperature in the cable terminal model. Adjust the maximum and minimum numbers of triangular elements until no obtuse angles appear.

[0075] Step S2: Based on the finite element model, perform electro-thermal coupling simulations for the simulated cable terminal bushing under multiple temperature conditions with different conductivities set for the simulated washer, and generate the electric field strength distribution data, simulated washer temperature distribution data, and current density distribution data of the simulated cable terminal bushing under different temperature conditions for each conductivity condition.

[0076] Specifically, based on the constructed multi-physics finite element model of the cable terminal bushing, accurately analyze the interactive effects of conductivity and temperature on the bushing performance through parametric scanning and multi-condition coupling simulations. In the COMSOL Multiphysics simulation platform, set a discretized scanning sequence for the conductivity parameter of the simulated washer (such as from 1×10 -14 S / m to 1×10 -11 S / m, with an order of magnitude step size ≤ 10 times), and at the same time superimpose the temperature condition parameters (30 °C, 40 °C, 50 °C, 70 °C) to construct a two-dimensional conductivity-temperature parameter matrix covering all possible material-environment combinations.

[0077] In each case of the conductivity parameter and temperature condition parameter of the simulated washer, synchronously solve the electromagnetic field and temperature field through the Newton-Raphson iteration algorithm.

[0078] Among them, the transient equation description formula for the electric potential in the quasi-static electric field in the bushing medium is as follows:

[0079]

[0080] In the formula, γ is the conductivity of the material; ε is the relative permittivity of the material; ρ v is the free charge volume density.

[0081] In the above formula, the influence of conduction current and dielectric on the potential distribution in the field is also considered. It can be used to solve the potential distribution of the linear electric field in the dielectric under any field source excitation. When the excitation voltage in the field is DC or power frequency AC and there is no free charge distribution, the field domain in the bushing can be described by the electrostatic field and the DC conduction field. Then, the simplified form of the above formula is as follows:

[0082]

[0083] where ε = ε0ε r .

[0084] The electric field strength equations at different positions in the bushing are as follows:

[0085]

[0086] In the formula, E is the electric field strength;

[0087] The basic equations of the electromagnetic field are as follows:

[0088]

[0089] J = σE + J e (6)

[0090]

[0091] In the formula, J is the current density; Q is the charge density; J e is the applied current density; σ is the conductivity; V is the electric potential. Add boundaries in the current field: terminal voltage ±500 kV, ground terminal voltage 0 V, and set contact impedance at the joint part, where the contact impedance satisfies the equation as follows:

[0092]

[0093] In the formula, ρ s is the surface resistance; C s is the surface capacitance; w is the angular frequency, and n is the number of contact points.

[0094] In the simulation of the coupled field of the cable bushing, the heat transfer mode is mainly heat conduction. The calculation of the heat field is mainly based on Fourier's heat conduction theorem, and its basic equation is as follows:

[0095]

[0096] In the formula, ρ is the density; C p is the constant pressure heat capacity; T is the temperature; k is the thermal conductivity; Q is the heat source; is the heat accumulation process; is the heat conduction process.

[0097] Combining equations (5) - (7) and equations (10) - (11) gives the electro - thermal coupling field equation as shown in equation (12):

[0098]

[0099] In the formula, Q e is the Joule heat source; Q e = J·E.

[0100] Under the temperature field, the boundary condition is mainly the natural convection between the cable sleeve and the external air domain. Adding the heat flux condition, it satisfies the following equation:

[0101]

[0102] q0 = h(T ext - T) (14)

[0103] In the formula, is the outer normal of the heat transfer surface, q0 is the convective heat flux, h is the heat transfer coefficient, and T ext is the external temperature. The value of the heat transfer coefficient h is taken as 12.5 W / (m2·K), and the value of the external temperature T ext is 293.15 K.

[0104] Step S3: According to the electric field strength distribution data and the current density distribution data, generate several first correlation curves corresponding to the simulated cable terminal sleeve, and generate the critical electric field value and the first slope corresponding to the first correlation curve; wherein, each of the first correlation curves is used to characterize the relationship between the current density and the electric field strength under a certain conductivity and a certain temperature condition;

[0105] In a preferred embodiment, the generating several first correlation curves corresponding to the simulated cable terminal sleeve according to the electric field strength distribution data and the current density distribution data, and generating the critical electric field value and the first slope corresponding to the first correlation curve includes:

[0106] According to the electric field strength distribution data and the current density distribution data, generate a first correlation curve for characterizing the relationship between the electric field strength and the current density under a certain conductivity and a certain temperature condition;

[0107] For each first correlation curve, perform piecewise linear fitting on the current first correlation curve to generate a linear fitting curve corresponding to the current first correlation curve; determine whether there is a segmentation point on the current linear fitting curve. If so, take the slope of the last segment of the current linear fitting curve as the first slope corresponding to the current first correlation curve, and take the electric field strength value of the last segmentation point as the critical electric field value corresponding to the current first correlation curve; if not, take the slope of the current linear fitting curve as the slope corresponding to the current first correlation curve, and take the preset electric field value as the critical electric field value corresponding to the current first correlation curve.

[0108] Specifically, based on the electric field strength distribution data and the current density distribution data, generate a first correlation curve (J-E curve) characterizing the relationship between the electric field strength and the current density for each set of conductivity and temperature conditions. By performing adaptive piecewise linear fitting on the J-E curve, potential inflection points are identified and the fitting accuracy is optimized. The specific process is as follows: First, use the curvature threshold detection algorithm to locate possible non-linear turning points, and then apply the weighted least squares method to independently fit each segment of data to ensure priority convergence in the high electric field strength region. During the fitting process, if a significant segmentation point is detected (such as the residual decrease rate exceeding 15%), take the slope of the last high electric field strength region as the non-linear conductivity coefficient (first slope), and calibrate the electric field strength value corresponding to this segmentation point as the critical electric field value; if the curve shows a global linear characteristic (the fitting residual is less than 5%), directly use the global slope as the conductivity coefficient, and at the same time preset a safety threshold according to the material breakdown field strength as the critical electric field value. This method ensures accurate quantification of the boundary between the Ohmic conduction region and the non-linear conduction region of the material under different conductivity and temperature conditions through dynamic discrimination of segmentation and adaptive parameter extraction, provides a unified dimension input of non-linear characteristic parameters for subsequent multi-objective optimization, and effectively solves the problems of field strength prediction deviation and heat loss evaluation inaccuracy caused by traditional methods ignoring the non-linear conduction mechanism.

[0109] Step S4: Group the first correlation curves with the same conductivity into one group to obtain several groups of first correlation curves; for each group of first correlation curves, extract the critical electric field values of each first correlation curve, and generate a second correlation curve characterizing the relationship between the critical electric field value and the temperature under a certain conductivity according to the extracted critical electric field values and the temperatures corresponding to each first correlation curve; calculate the conduction stability index corresponding to each conductivity according to the first slopes of each first correlation curve in the first correlation curve group; determine the peak temperature of the simulation gasket under each conductivity according to the simulation gasket temperature distribution data.

[0110] Specifically, after obtaining the first correlation curves (J-E curves) under each conductivity and temperature condition, the conductivity grouping analysis, critical electric field-temperature correlation modeling, and conduction stability quantification are realized through the following steps:

[0111] All the first correlation curves with the same conductivity parameter are classified into the same group (for example, the curves under the working conditions of 30 °C, 40 °C, 50 °C, and 70 °C corresponding to σ = 1×10-12 S / m form a group), forming multiple curve sets classified by conductivity. For each group of curves, the critical electric field values (Eth i ) at each temperature working condition are extracted, combined with the corresponding temperature (T i ), and the second correlation curve (Eth-T curve) of the critical electric field varying with temperature is generated by fitting using the least square linear regression or exponential decay model to quantify the temperature sensitivity of the conductivity material. For example, the fitting equation of a certain conductivity group is Eth(T) = Eth0·exp(-λT), where λ is the temperature decay coefficient, reflecting the degradation rate of the electric field tolerance ability of the material at high temperatures;

[0112] In one embodiment, the fitting equation of the J-E curve in linear coordinates is as shown in the following formula:

[0113]

[0114] In the formula, n is the carrier concentration; X is the activation energy; l is the hopping distance of the charge carriers; T is the thermodynamic temperature; J n is the current density; d is the characteristic thickness of the material; U is the carrier mobility; e is the elementary charge; k b is the Boltzmann constant.

[0115] For the first correlation curves of different temperature working conditions within the same conductivity group, the first slope (β 1，i ) is extracted, and the variance of the slope of this group in the temperature dimension is calculated:

[0116]

[0117] In the formula, N is the number of temperature working conditions; is the average slope. The smaller the variance value, the more stable the conduction characteristics of the material are to temperature changes, and vice versa, there are significant non-linear fluctuations.

[0118] Based on the simulated washer temperature distribution data corresponding to each conductivity, the highest temperature value (T max ) in the washer area under all temperature working conditions is screened as the peak temperature index of this conductivity material. For example, when a certain conductivity σ = 5×10 -13 S / m, its T max at 30 °C to 70 °C working conditions are 58 °C, 67 °C, 75 °C, and 82 °C respectively, reflecting the non-linear intensification effect of the material's heat accumulation with the increase of the ambient temperature. By correlating the slope of the Eth-T curve, the conduction stability index, and T max , a three-dimensional optimization space of conductivity-temperature-field strength stability can be constructed to provide a quantitative basis for multi-objective decision-making.

[0119] In a preferred embodiment, calculating a conduction stability index corresponding to each conductivity according to the first slopes of the first correlation curves in the first correlation curve group includes:

[0120] For each correlation curve group, calculate the variance of the first slopes of the first correlation curves in the current correlation curve group as the conduction stability index corresponding to the current conductivity.

[0121] In a preferred embodiment, determining the peak temperature of the simulation gasket at each conductivity according to the simulation gasket temperature distribution data includes:

[0122] Group the simulation gasket temperature distribution data with the same conductivity into one group to obtain several groups of simulation gasket temperature distribution data;

[0123] For each group of simulation gasket temperature distribution data, extract the peak gasket temperature of each simulation gasket temperature distribution data; use the highest peak temperature as the peak temperature of the simulation gasket at the current conductivity.

[0124] Step S5, determining the optimized conductivity value of the gasket according to the second correlation curve, conduction stability index and peak temperature of the simulation gasket at each conductivity;

[0125] In a preferred embodiment, determining the optimized conductivity value of the gasket according to the second correlation curve, conduction stability index and peak temperature of the simulation gasket at each conductivity includes:

[0126] For each second correlation curve, perform least squares linear regression on the current second correlation curve within a preset temperature range to generate a fitting line for characterizing the relationship between the critical electric field value and temperature at a certain conductivity, and use the slope of the current fitting line as the critical electric field attenuation index at the current conductivity;

[0127] Determine the optimized conductivity value of the gasket according to the critical electric field attenuation index, conduction stability index and peak temperature of the simulation gasket at each conductivity;

[0128] Calculate the comprehensive heating index of the simulation cable terminal bushing under each conductivity condition based on the peak temperature, the critical electric field attenuation index and the conduction stability index;

[0129] Use the conductivity corresponding to the lowest comprehensive heating index as the optimized conductivity value of the gasket.

[0130] Specifically, for each second correlation curve, within a preset temperature range (such as 30°C to 70°C), the variation trend of the critical electric field value (Eth) with temperature (T) is linearly regressed and fitted by the least squares method to generate a fitted straight line equation Eth(T) = αT + β, and the absolute value of the slope α is defined as the critical electric field decay index of the current conductivity (α = |dEth / dT|). This index quantifies the degradation rate of the electric field tolerance ability of the material at high temperatures. For example, α = 0.2 MV / (mm·°C) means that for every 1°C increase in temperature, the critical electric field decreases by 0.2 MV / mm, directly reflecting the thermal-electric field stability of the material.

[0131] Combining the critical electric field decay index (α), the conduction stability index (Var(β1)) of each conductivity, and the peak temperature (T max ) of the simulation gasket, the comprehensive heating index is calculated through normalized weighted calculation:

[0132] In a preferred embodiment, the comprehensive heating index is calculated by the following formula:

[0133] I(σ) = k1·T peak (σ) + k2·α(σ) + k3·Var(σ) (17)

[0134] where I(σ) is the comprehensive heating index corresponding to the conductivity σ; k1 is the weight coefficient of the peak temperature; k2 is the weight coefficient of the critical electric field decay index; k3 is the weight coefficient of the conduction stability index; T peak (σ) is the peak temperature of the conductivity σ; α(σ) is the critical electric field decay index of the conductivity σ; Var(σ) is the conduction stability index of the conductivity σ.

[0135] Step S6: When the conductivity of the currently set gasket is not the conductivity optimization value, select the corresponding gasket according to the conductivity optimization value and replace the currently set gasket.

[0136] Specifically, after determining the conductivity optimization value, if there is a deviation between the conductivity of the currently set gasket and the optimization value (such as the deviation exceeds 10%), the dynamic replacement mechanism is triggered, and the gradient composite material gasket with the conductivity closest to the optimization value is matched through the preset material library. The candidate material with a deviation ≤ 5% is preferentially selected, and the robot-assisted disassembly device is used to remove the old gasket and install the new gasket.

[0137] Based on the above method item embodiments, the present invention correspondingly provides device item embodiments.

[0138] Such as Figure 5As shown in the figure, an embodiment of the present invention provides an optimization device for a cable terminal bushing, including: a finite element model acquisition module, a multi-physical field coupling simulation module, a current density - electric field strength correlation modeling module, a critical electric field - temperature correlation analysis module, a conductivity optimization value decision module, and a conductivity adaptation optimization module;

[0139] The finite element model acquisition module is used to acquire the finite element model of the cable terminal bushing; wherein, the finite element model includes a simulated cable terminal bushing provided with a simulated gasket;

[0140] The multi-physical field coupling simulation module is used to perform electro-thermal coupling simulation of the simulated cable terminal bushing under multiple temperature conditions based on the finite element model under the condition of setting different conductivities for the simulated gasket, and generate the electric field strength distribution data, the simulated gasket temperature distribution data, and the current density distribution data of the simulated cable terminal bushing under different temperature conditions under each conductivity condition;

[0141] The current density - electric field strength correlation modeling module is used to generate a number of first correlation curves corresponding to the simulated cable terminal bushing according to the electric field strength distribution data and the current density distribution data, and generate the critical electric field value and the first slope corresponding to the first correlation curve; wherein, each of the first correlation curves is used to characterize the relationship between the current density and the electric field strength under a conductivity and a temperature condition;

[0142] The critical electric field - temperature correlation analysis module is used to divide the first correlation curves with the same conductivity into a group to obtain a number of first correlation curve groups; for each first correlation curve group, extract the critical electric field values of the first correlation curves, and generate a second correlation curve for characterizing the relationship between the critical electric field value and the temperature under a conductivity according to the extracted critical electric field values and the temperatures corresponding to the first correlation curves; calculate the conduction stability index corresponding to each conductivity according to the first slopes of the first correlation curves in the first correlation curve group; and determine the peak temperature of the simulated gasket under each conductivity according to the simulated gasket temperature distribution data;

[0143] The conductivity optimization value decision module is used to determine the conductivity optimization value of the gasket according to the second correlation curves, the conduction stability index of each conductivity, and the peak temperature of the simulated gasket;

[0144] The conductivity adaptation optimization module is used to select a corresponding gasket according to the conductivity optimization value and replace the currently set gasket when the conductivity of the currently set gasket is not the conductivity optimization value.

[0145] It should be noted that the embodiments of the devices described above correspond to the above embodiments of the present invention and can implement the optimization method of the cable terminal bushing described in any one of the above of the present invention. In addition, the embodiments of the above devices are merely illustrative. The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. In addition, in the attached drawings of the device embodiments provided by the present invention, the connection relationship between modules indicates that they have a communication connection, which can be specifically implemented as one or more communication buses or signal lines. Those of ordinary skill in the art can understand and implement without creative efforts.

[0146] Based on the above method embodiment of the present invention, a corresponding embodiment of an electronic device is provided.

[0147] An embodiment of the present invention provides an electronic device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, the optimization method of the cable terminal bushing described in any one of the present invention is implemented, or when the processor executes the computer program, the functions of each module in the above device embodiments are implemented.

[0148] Exemplarily, the computer program can be divided into one or more modules. The one or more modules are stored in the memory and executed by the processor to complete the present invention. The one or more modules can be a series of computer program instruction segments capable of completing specific functions, and these instruction segments are used to describe the execution process of the computer program in the terminal device.

[0149] The terminal device can be a computing device such as a desktop computer, a notebook, a palm computer, and a cloud server. The terminal device may include, but is not limited to, a processor and a memory.

[0150] The so-called processor may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The processor is the control center of the terminal device and connects all parts of the entire terminal device through various interfaces and circuits.

[0151] The memory can be used to store the computer programs and / or modules. The processor realizes various functions of the terminal device by running or executing the computer programs and / or modules stored in the memory, and by calling the data stored in the memory. The memory mainly includes a program storage area and a data storage area. Among them, the program storage area can store an operating system, application programs required for at least one function, etc.; the data storage area can store data created according to the use of the mobile phone, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as a hard disk, memory, plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, Flash Card, at least one magnetic disk storage device, flash device, or other volatile solid-state storage devices.

[0152] Based on the above method item embodiments, the present invention correspondingly provides storage medium item embodiments;

[0153] Another embodiment of the present invention provides a storage medium. The storage medium includes a stored computer program. When the computer program runs, it controls the device where the storage medium is located to execute any one of the above optimization methods for the cable terminal sleeve of the present invention.

[0154] Among them, the above storage medium is a computer-readable storage medium, and the computer program includes computer program code, which can be in the form of source code, object code, executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disc, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content included in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0155] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example" or "some examples", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0156] The above is the preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A method for optimizing a cable terminal sleeve, characterized in that: A gasket is provided at the joint of the cable terminal sleeve; the optimization method comprises: Obtaining a finite element model of a cable terminal bushing; wherein the finite element model includes a simulated cable terminal bushing provided with a simulated gasket; Based on the finite element model, an electric-thermal coupling simulation of multiple temperature conditions is performed on the simulated cable terminal bushing under the condition of setting different conductivities for the simulated gasket, and electric field intensity distribution data of the simulated cable terminal bushing under different temperature conditions under various conductivities, simulated gasket temperature distribution data, and current density distribution data are generated; According to the electric field intensity distribution data and the current density distribution data, a plurality of first correlation curves corresponding to the simulated cable terminal bushing are generated, and a critical electric field value and a first slope corresponding to the first correlation curve are generated; wherein each of the first correlation curves is used to characterize the relationship between the current density and the electric field intensity under a conductivity and a temperature condition; The first correlation curves with the same conductivity are grouped into a group to obtain a plurality of first correlation curve groups; for each first correlation curve group, the critical electric field value of each first correlation curve is extracted, and a second correlation curve for characterizing the relationship between the critical electric field value and the temperature under a conductivity is generated according to the extracted critical electric field value and the temperature corresponding to each first correlation curve; the conduction stability index corresponding to each conductivity is calculated according to the first slope of each first correlation curve in the first correlation curve group; the peak temperature of the simulated gasket under each conductivity is determined according to the simulated gasket temperature distribution data; Determining an optimized conductivity value of the gasket according to the second correlation curve of each conductivity, the conductive stability index, and the peak temperature of the simulated gasket; When the conductivity of the currently set gasket is not the conductivity optimization value, a corresponding gasket is selected according to the conductivity optimization value to replace the currently set gasket.

2. The cable terminal sleeve optimization method according to claim 1, characterized in that: The step of obtaining a finite element model of the cable terminal sleeve comprises: Obtaining geometric parameters, material parameters and operating condition parameters of the cable terminal bushing; Constructing a three-dimensional geometric model of the cable terminal bushing according to the geometric parameters; Based on the Delaunay triangulation algorithm, the three-dimensional geometric model is meshed to generate a mesh model of the cable terminal sleeve; The material parameters and operating condition parameters are coupled to the mesh model to generate a finite element model of the cable terminal bushing.

3. The method for optimizing the cable terminal sleeve according to claim 2, characterized in that: The step of generating a plurality of first correlation curves corresponding to the simulated cable terminal bushing according to the electric field intensity distribution data and the current density distribution data, and generating a critical electric field value and a first slope corresponding to the first correlation curves, comprises: Generating a first correlation curve for characterizing the relationship between electric field intensity and current density under a conductivity and temperature condition according to the electric field intensity distribution data and the current density distribution data; For each first association curve, a piecewise linear fitting is performed on the current first association curve to generate a linear fitting curve corresponding to the current first association curve; it is determined whether the current linear fitting curve has a segmentation point. If so, the slope of the last segment in the current linear fitting curve is used as the first slope corresponding to the current first association curve, and the electric field strength value of the last segmentation point is used as the critical electric field value corresponding to the current first association curve; if not, the slope of the current linear fitting curve is used as the slope corresponding to the current first association curve, and the preset electric field value is used as the critical electric field value corresponding to the current first association curve.

4. The method for optimizing the cable terminal sleeve according to claim 3, characterized in that: The step of calculating the conduction stability index corresponding to each conductivity according to the first slope of each first correlation curve in the first correlation curve group includes: For each correlation curve group, the variance of the first slope of each first correlation curve in the current correlation curve group is calculated as the conduction stability index corresponding to the current conductivity.

5. The cable terminal bushing optimization method according to claim 4, characterized in that: Determining the peak temperature of the simulated gasket at each conductivity according to the simulated gasket temperature distribution data includes: The simulated gasket temperature distribution data with the same conductivity are grouped into one group to obtain a plurality of simulated gasket temperature distribution data groups; For each simulated gasket temperature distribution data set, the gasket peak temperature of each simulated gasket temperature distribution data is extracted; and the peak temperature with the highest gasket peak temperature is taken as the peak temperature of the simulated gasket of the current conductivity.

6. The cable terminal bushing optimization method according to claim 5, characterized in that: The step of determining the conductivity optimization value of the gasket according to the second correlation curve of each conductivity, the conduction stability index and the peak temperature of the simulated gasket comprises: For each second correlation curve, a least squares linear regression is performed on the current second correlation curve within a preset temperature range to generate a fitting straight line for characterizing the relationship between the critical electric field value and the temperature under a certain conductivity, and the slope of the current fitting straight line is used as the critical electric field attenuation index of the current conductivity; Determining the conductivity optimization value of the gasket according to the critical electric field decay index of each conductivity, the conduction stability index and the peak temperature of the simulated gasket; The peak temperature, the critical electric field attenuation index and the conduction stability index are used to calculate the comprehensive heating index of the simulated cable terminal bushing under various conductivity conditions; The corresponding conductivity with the lowest comprehensive heating index is taken as the optimized conductivity value of the gasket.

7. The cable terminal bushing optimization method according to claim 6, characterized in that: The comprehensive fever index is calculated by the following formula: I(σ)=k1·T peak (σ)+k2·α(σ)+k3·Var(σ) Where I(σ) is the comprehensive heating index corresponding to the conductivity σ; k1 is the weight coefficient of the peak temperature; k2 is the weight coefficient of the critical electric field attenuation index; k3 is the weight coefficient of the conduction stability index; T peak (σ) is the peak temperature of conductivity σ; α(σ) is the critical electric field decay index of conductivity σ; Var(σ) is the conduction stability index of conductivity σ.

8. An optimization device for a cable terminal sleeve, characterized in that: include: Finite element model acquisition module, multi-physics field coupling simulation module, current density-electric field strength correlation modeling module, critical electric field-temperature correlation analysis module, conductivity optimization value decision module and conductivity adaptation optimization module; The finite element model acquisition module is used to acquire a finite element model of a cable terminal bushing; wherein the finite element model includes a simulated cable terminal bushing provided with a simulated gasket; The multi-physics field coupling simulation module is used to perform an electric-thermal coupling simulation of multiple temperature conditions on the simulated cable terminal bushing under the condition of setting different conductivities for the simulated gasket based on the finite element model, and generate electric field intensity distribution data of the simulated cable terminal bushing under different temperature conditions under various conductivities, simulated gasket temperature distribution data, and current density distribution data; The current density-electric field strength correlation modeling module is used to generate a plurality of first correlation curves corresponding to the simulated cable terminal bushing according to the electric field strength distribution data and the current density distribution data, and generate a critical electric field value and a first slope corresponding to the first correlation curve; wherein each of the first correlation curves is used to characterize the relationship between current density and electric field strength under a conductivity and a temperature condition; The critical electric field-temperature correlation analysis module is used to group the first correlation curves with the same conductivity into a group to obtain a plurality of first correlation curve groups; for each first correlation curve group, extract the critical electric field value of each first correlation curve, and generate a second correlation curve for characterizing the relationship between the critical electric field value and the temperature under a conductivity according to the extracted critical electric field value and the temperature corresponding to each first correlation curve; calculate the conduction stability index corresponding to each conductivity according to the first slope of each first correlation curve in the first correlation curve group; determine the peak temperature of the simulated gasket under each conductivity according to the simulated gasket temperature distribution data; The conductivity optimization value decision module is used to determine the conductivity optimization value of the gasket according to the second correlation curve of each conductivity, the conduction stability index and the peak temperature of the simulated gasket; The conductivity adaptation optimization module is used to select a corresponding gasket according to the conductivity optimization value and replace the currently set gasket when the conductivity of the currently set gasket is not the conductivity optimization value.

9. An electronic device, characterized in that: The invention comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the method for optimizing the cable terminal sleeve according to any one of claims 1 to 7 can be implemented.

10. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the cable terminal bushing optimization method according to any one of claims 1 to 7 can be implemented.

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