Calculation method and system for electric field distribution of high-voltage AC extruded insulated cables

Abstract

The present invention relates to a method and system for calculating the electric field distribution of a high-voltage AC extruded insulated cable, belonging to the field of electrical engineering technology. First, a non-homogeneous structural geometric model of an insulating layer of the high-voltage AC extruded insulated cable is constructed, and then a first molecular structural model of a crystalline region of the insulating layer and a second molecular structural model of an amorphous region of the insulating layer are respectively constructed. Molecular dynamics simulation calculations are performed based on the first molecular structural model to obtain dielectric parameters of the crystalline region. Molecular dynamics simulation calculations are performed based on the second molecular structural model to obtain dielectric parameters of the amorphous region. Finally, the non-homogeneous structural geometric model, the dielectric parameters of the crystalline region, and the dielectric parameters of the amorphous region are imported into simulation software for simulation calculation to obtain an electric field distribution result of the insulating layer. Thus, the electric field distribution calculation is performed based on consideration of the internal non-homogeneous structure of the insulating layer, and a more comprehensive and accurate electric field distribution result can be obtained.

Description

Technical Field

[0001] The present invention relates to the field of electrical engineering technology, and in particular to a method and system for calculating the electric field distribution of a high-voltage AC extruded insulated cable. Background Art

[0002] Currently, the core goal of the energy revolution and transformation is to build a new generation of clean, low-carbon, safe and efficient energy system. Therefore, significantly increasing the proportion of electricity in terminal energy consumption is particularly important.

[0003] High-voltage cable transmission boasts advantages such as large transmission capacity, long distances, high efficiency, and low losses, making it a reliable technology for meeting the needs of large-capacity, long-distance, interregional power transmission. As a key component of high-voltage cable transmission, high-voltage AC (alternating current) cable transmission boasts advantages such as a small footprint, low line costs, high transmission stability, and enhanced safety. Polyolefin insulation, a material used in high-voltage AC cables, offers outstanding advantages such as high dielectric strength, low dielectric loss, and strong deformation resistance. Therefore, it is widely used as the primary insulating material in AC cables of all voltage levels. However, the insulation properties of these materials can irreversibly degrade under the long-term influence of AC electric fields, particularly due to localized electric field distortion within them. This strong electric field can cause electrical treeing in the insulation material, and in severe cases, even lead to insulation breakdown, severely restricting the stable operation of power equipment. Therefore, studying the internal electric field distribution characteristics of high-voltage AC extruded insulated cables is essential and urgent.

[0004] However, current research on the electric field distribution characteristics within insulating materials under the action of high-voltage AC electric fields treats insulating materials as homogeneous materials, assuming that the electric field distribution within the material is uniform. This is inconsistent with the actual situation of semi-crystalline insulating materials. Due to differences in dielectric and energy level characteristics at different internal structures, the electric field at different structures within the insulating material is not uniformly distributed, and local electric field distortion may occur, leading to partial discharge and, in severe cases, insulation breakdown. Therefore, existing methods for simulating the electric field within AC cables are not accurate. In order to more accurately and quantitatively evaluate the insulation performance of AC cables, further revisions and improvements to the electric field simulation methods within insulating materials are needed.

[0005] Based on this, a new calculation scheme for the electric field distribution considering the heterogeneous structure of high-voltage AC extruded insulated cables is urgently needed. Summary of the Invention

[0006] The purpose of the present invention is to provide a method and system for calculating the electric field distribution of high-voltage AC extruded insulated cables, which can accurately calculate the electric field distribution inside the cable insulation layer, thereby providing theoretical guidance and model support for the analysis of the electric field distribution characteristics of high-voltage AC extruded insulated cables.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] A method for calculating the electric field distribution of a high-voltage AC extruded insulated cable, the method comprising:

[0009] Construct a non-homogeneous structural geometric model of the insulation layer of a high-voltage AC extruded insulated cable;

[0010] Constructing a first molecular structure model of the crystalline region of the insulating layer and a second molecular structure model of the amorphous region of the insulating layer respectively; performing molecular dynamics simulation calculations based on the first molecular structure model to obtain dielectric parameters of the crystalline region; and performing molecular dynamics simulation calculations based on the second molecular structure model to obtain dielectric parameters of the amorphous region;

[0011] The inhomogeneous structural geometric model, the dielectric parameters of the crystalline region, and the dielectric parameters of the amorphous region are imported into simulation software for simulation calculation to obtain the electric field distribution result of the insulating layer.

[0012] A system for calculating the electric field distribution of a high-voltage AC extruded insulated cable, the system comprising:

[0013] A geometric model building module is used to build a non-homogeneous structural geometric model of the insulation layer of a high-voltage AC extruded insulated cable;

[0014] a dielectric parameter calculation module, configured to respectively construct a first molecular structure model of the crystalline region of the insulating layer and a second molecular structure model of the amorphous region of the insulating layer; perform molecular dynamics simulation calculations based on the first molecular structure model to obtain dielectric parameters of the crystalline region; and perform molecular dynamics simulation calculations based on the second molecular structure model to obtain dielectric parameters of the amorphous region;

[0015] The simulation calculation module is used to import the inhomogeneous structural geometric model, the dielectric parameters of the crystalline region and the dielectric parameters of the amorphous region into simulation software for simulation calculation to obtain the electric field distribution result of the insulating layer.

[0016] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0017] The present invention is used to provide a method and system for calculating the electric field distribution of a high-voltage AC extruded insulated cable. The method first constructs a heterogeneous structural geometric model of the insulating layer of the high-voltage AC extruded insulated cable, then constructs a first molecular structure model of the crystalline region of the insulating layer and a second molecular structure model of the amorphous region of the insulating layer, performs molecular dynamics simulation calculations based on the first molecular structure model to obtain the dielectric parameters of the crystalline region, performs molecular dynamics simulation calculations based on the second molecular structure model to obtain the dielectric parameters of the amorphous region, and finally imports the heterogeneous structural geometric model, the dielectric parameters of the crystalline region, and the dielectric parameters of the amorphous region into simulation software for simulation calculation to obtain the electric field distribution result of the insulating layer. Thus, the electric field distribution calculation is performed based on the heterogeneous structure inside the insulating layer, and a more comprehensive and accurate electric field distribution result can be obtained. Among them, the construction of the heterogeneous structural geometric model visualizes the heterogeneous structure of the polyolefin insulation material, the molecular dynamics simulation calculation obtains the difference in the intrinsic dielectric properties of the crystalline region and the amorphous region, and the physical field simulation calculation obtains the electric field distribution law inside the high-voltage cable insulation layer. This method provides theoretical guidance and model support for the study of the electric field characteristics of the high-voltage AC extruded insulated cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A flow chart of the calculation method provided in Example 1 of the present invention;

[0020] Figure 2 This is a principle block diagram of the calculation method provided in Example 1 of the present invention;

[0021] Figure 3 A schematic diagram of a three-phase model of the internal structure of an insulating material provided in Example 1 of the present invention;

[0022] Figure 4 This is a principle block diagram of the process of constructing a geometric model of a heterogeneous structure provided in Example 1 of the present invention;

[0023] Figure 5 A schematic diagram of a geometric model of a heterogeneous structure provided in Example 1 of the present invention;

[0024] Figure 6 This is a principle block diagram of the molecular structure model construction and numerical solution calculation process of the crystalline region and the amorphous region provided in Example 1 of the present invention;

[0025] Figure 7 A schematic diagram of the intermediate molecular structure model of the crystalline region and the amorphous region provided in Example 1 of the present invention;

[0026] Figure 8 This is a principle block diagram of the simulation calculation process provided in Example 1 of the present invention;

[0027] Figure 9 Schematic diagram of the electric field distribution in the crystalline region and amorphous region of the polyolefin insulation material provided in Example 1 of the present invention;

[0028] Figure 10 This is a system block diagram of the computing system provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] The purpose of the present invention is to provide a calculation method and system for the electric field distribution of a high-voltage AC extruded insulated cable taking into account the heterogeneous structure of the polyolefin insulation material of the extruded insulated cable. The method belongs to the technical field at the intersection of electrical engineering, polymer materials and physics. The method can simulate the characteristics of the electric field inside the insulation layer and calculate the electric field distribution inside the cable insulation layer, thereby providing theoretical guidance and model support for the analysis of the electric field characteristics of high-voltage AC extruded insulated cables and solving the problem of inaccuracy and incompleteness of existing calculation methods.

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Example 1:

[0033] This embodiment is used to provide a method for calculating the electric field distribution of a high-voltage AC extruded insulated cable. Figure 1 and Figure 2 As shown, the calculation method includes:

[0034] S1: Construct a non-homogeneous structural geometric model of the insulation layer of a high-voltage AC extruded insulated cable;

[0035] Specifically, this embodiment is based on the heterogeneous structure of the insulation layer of the high-voltage AC extruded insulated cable, and constructs a heterogeneous structural geometric model with a similar structure. Considering that the insulation layer is not a homogeneous material, but a heterogeneous structure with crystalline regions, amorphous regions and the interface between the two phases, its three-phase model is as follows: Figure 3 Based on this, this embodiment constructs a heterogeneous structural geometric model of insulating materials with similar structures based on the Voronoi network model, as shown in FIG. Figure 4 As shown in Figure 2, the construction process of the heterogeneous structure geometric model includes:

[0036] (1) Make samples of the insulation layer of high-voltage AC extruded insulated cables.

[0037] In this embodiment, a portion of the insulation layer of the high-voltage AC extruded insulated cable can be arbitrarily cut off as a sample as needed.

[0038] (2) Test the sample to determine the size of the sample, the number of spherulites in the sample, and the volume ratio of the crystalline area to the amorphous area in the sample. The size includes length and width.

[0039] In this embodiment, a polarizing microscope can be used to detect the sample, and the width can be understood as the thickness of the insulating layer.

[0040] (3) Draw the boundary of the heterogeneous structure geometric model according to the size, randomly set multiple Voronoi seed points within the boundary, and generate a Voronoi diagram; fill the crystalline region and the amorphous region in each Voronoi polygon in the Voronoi diagram according to the volume ratio to obtain a heterogeneous structure geometric model. The number of Voronoi seed points is the same as the number of spherulites, and the amorphous region filled in the Voronoi polygon is set around the crystalline region filled in the Voronoi polygon.

[0041] like Figure 5 As shown, the length of the dimension is equal to the length of the two-dimensional boundary of the inhomogeneous structural geometric model, and the width of the dimension is equal to the width of the two-dimensional boundary of the inhomogeneous structural geometric model, so as to draw the two-dimensional boundary of the inhomogeneous structural geometric model. The shape of the two-dimensional boundary is generally a rectangle. Within the two-dimensional boundary, the same number of Voronoi seed points is set according to the number of spherulites, and the perpendicular bisectors of the lines connecting adjacent seed points intersect to form a Voronoi diagram including multiple Voronoi polygons. The process of generating the Voronoi diagram from the Voronoi seed points can adopt the existing technology and will not be repeated here. According to the crystallization characteristics of the insulating layer itself, the area ratio of the crystalline region and the amorphous region in the insulating layer is referred to to set the proportion of the two in the Voronoi diagram. Specifically, the crystalline region and the amorphous region are filled in equal proportion in each Voronoi polygon according to the volume ratio, and the amorphous region is arranged around the crystalline region to obtain the inhomogeneous structural geometric model of the insulating layer. Figure 5 In the figure, the black lines are Voronoi polygons, the gray part is the crystalline area, and the white part is the amorphous area.

[0042] Traditional research models for the internal electric field distribution characteristics of cable insulation materials regard them as homogeneous structures, ignoring the differences between crystalline and amorphous regions. The inhomogeneous structural geometric model of the insulation material described in this embodiment provides analytical ideas and specific methods for the electric field distribution of the microstructure of the insulation material.

[0043] S2: constructing a first molecular structure model of the crystalline region of the insulating layer and a second molecular structure model of the amorphous region of the insulating layer respectively; performing molecular dynamics simulation calculations based on the first molecular structure model to obtain dielectric parameters of the crystalline region; and performing molecular dynamics simulation calculations based on the second molecular structure model to obtain dielectric parameters of the amorphous region;

[0044] In this embodiment, molecular structure models of the crystalline region and the amorphous region inside the insulating material are constructed respectively, and the intrinsic dielectric properties thereof are studied by molecular dynamics simulation calculation means, and the relevant dielectric parameters of the crystalline region and the amorphous region are calculated.

[0045] In S2, respectively constructing the first molecular structure model of the crystalline region of the insulating layer and the second molecular structure model of the amorphous region of the insulating layer may include: respectively drawing the first molecular chain of the crystalline region of the insulating layer and the second molecular chain of the amorphous region of the insulating layer; geometrically optimizing the first molecular chain to obtain a first optimized molecular chain, and geometrically optimizing the second molecular chain to obtain a second optimized molecular chain; periodically filling the unit cell with the first optimized molecular chain to obtain a first initial molecular structure model, and periodically filling the unit cell with the second optimized molecular chain to obtain a second initial molecular structure model; energy optimizing the first initial molecular structure model to obtain a first intermediate molecular structure model, and energy optimizing the second initial molecular structure model to obtain a second intermediate molecular structure model; geometrically optimizing the first intermediate molecular structure model to obtain a first molecular structure model of the crystalline region, and geometrically optimizing the second intermediate molecular structure model to obtain a second molecular structure model of the amorphous region.

[0046] Optimizing the geometric model of the first intermediate molecular structure model may include: first performing an annealing process on the first intermediate molecular structure model using an isothermal and isobaric ensemble for multiple cycles, and then performing an annealing process on the first intermediate molecular structure model using an isothermal and isobaric ensemble. Optimizing the geometric model of the second intermediate molecular structure model may include: first performing an annealing process on the second intermediate molecular structure model using an isothermal and isobaric ensemble for multiple cycles, and then performing an annealing process on the second intermediate molecular structure model using an isothermal and isobaric ensemble.

[0047] After constructing the molecular structure model of the crystalline region and the amorphous region, a dynamic simulation process can be performed. In S2, the dielectric parameters include the dielectric constant. Then, performing molecular dynamics simulation calculations based on the first molecular structure model to obtain the dielectric parameters of the crystalline region can include: performing molecular dynamics simulation calculations based on the first molecular structure model to obtain the dipole autocorrelation function of the crystalline region; calculating the frequency-dependent dielectric constant of the crystalline region based on the dipole autocorrelation function of the crystalline region, the frequency-dependent dielectric constant being a function of the dielectric constant varying with frequency; determining the dielectric constant of the crystalline region based on the frequency-dependent dielectric constant of the crystalline region, specifically substituting the operating frequency of the cable under the AC electric field into the frequency-dependent dielectric constant of the crystalline region to determine the dielectric constant of the crystalline region. Performing molecular dynamics simulation calculations based on the second molecular structure model to obtain the dielectric parameters of the amorphous region may include: performing molecular dynamics simulation calculations based on the second molecular structure model to obtain a dipole autocorrelation function of the amorphous region; calculating a frequency-dependent dielectric constant of the amorphous region based on the dipole autocorrelation function of the amorphous region, where the frequency-dependent dielectric constant is a function of how the dielectric constant varies with frequency; and determining the dielectric constant of the amorphous region based on the frequency-dependent dielectric constant of the amorphous region, specifically substituting the operating frequency of the cable under an alternating current electric field into the frequency-dependent dielectric constant of the amorphous region to determine the dielectric constant of the amorphous region.

[0048] Calculating the frequency-dependent dielectric constant based on the dipole autocorrelation function may include: calculating the frequency-dependent dielectric constant based on the dipole autocorrelation function by using a correlation relationship between the frequency-dependent dielectric constant and the dipole autocorrelation function.

[0049] The association relationship is:

[0050]

[0051] in, is the frequency-dependent dielectric constant, representing the frequency The dielectric constant under ; is the optical frequency dielectric constant, which represents the dielectric constant value when the frequency is infinite; is the static dielectric constant, which represents the dielectric constant value when the frequency approaches 0 infinitely; is the dipole autocorrelation function; t For time.

[0052] In this embodiment, the above process of constructing the first molecular structure model of the crystalline region of the insulating layer and the second molecular structure model of the amorphous region of the insulating layer can be implemented using Materials Studio software. Figure 6 As shown, the above molecular structure model construction and numerical solution calculation process may include:

[0053] (1) Preliminary construction of molecular structure models of crystalline and amorphous regions:

[0054] The Visualizar module is used to draw the molecular chains of the crystalline and amorphous regions of polyolefins respectively.

[0055] The Forcite module is used to geometrically optimize the molecular chains of the crystalline and amorphous regions to obtain the optimized molecular chains of the polyolefin crystalline and amorphous regions with the lowest potential energy conformation.

[0056] The optimized molecular chains of the crystalline region and the amorphous region are placed into the periodic unit cell through the Construction command of the Amorphous cell module to obtain the initial molecular structure model of the crystalline region and the amorphous region.

[0057] The Construction command of the Amorphous cell module is used to optimize the energy of the initial molecular structure model of the crystalline region and the amorphous region until the energy converges, and the intermediate molecular structure model of the crystalline region and the amorphous region of the polyolefin insulation material is constructed, such as Figure 7 shown.

[0058] (2) Annealing treatment and model optimization:

[0059] For the molecular structure model of the intermediate region between the crystalline and amorphous regions of polyolefin insulation material, five cycles of annealing were performed using the Anneal command in the Forcite module. The annealing ensemble was set to the constant pressure and temperature (NPT) ensemble to complete the volume relaxation process in the molecular structure model between the crystalline and amorphous regions. Parameters set for this process included the temperature range and run duration, for example, 50 ps at each temperature from 333K to 500K.

[0060] The constant volume and temperature (NVT) ensemble within the canonical ensemble was selected for further annealing, completing the geometric model optimization process and obtaining the molecular structure models of the crystalline and amorphous regions. Parameters set during this process included temperature, dynamics duration, step size, and numerical integration. For example, the temperature was set to 333K, the dynamics duration to 800 ps, ​​the step size to 1 fs, and the numerical integration to 5000 steps per frame.

[0061] (3) Numerical solution calculation:

[0062] This example uses molecular dynamics simulation (used to simulate the material's own parameter properties) to solve the dipole autocorrelation function (DACF) of the crystalline and amorphous regions of the polyolefin insulation material. This function describes the change in dipole moment by comparing the positional transformations between group clusters in the composite model. It is defined as:

[0063] ;

[0064] in, is the dipole autocorrelation function; t For time; M (0) is the molecular chain dipole moment at the initial moment; M ( t )for t The molecular chain dipole moment at time is t The scalar product of the charge of the molecular chain and its position vector at the moment; M (0) M (t)> is the total number of molecular chains in the system M (0) and in t At the moment M ( t ) is the average of the sum of the products of the quantities.

[0065] The frequency-dependent dielectric constants of the crystalline and amorphous regions can be calculated based on the correlation between the frequency-dependent dielectric constant and the dipole autocorrelation function. The dielectric constant values ​​of the cable at an operating frequency of 50 Hz under an AC electric field are selected as the dielectric constants of the crystalline and amorphous regions.

[0066] The relationship between the frequency-dependent dielectric constant and the dipole autocorrelation function satisfies:

[0067]

[0068] in, is the frequency-dependent dielectric constant, representing the frequency The dielectric constant under ; is the optical frequency dielectric constant, which represents the dielectric constant value when the frequency is infinite; is the static dielectric constant, which represents the dielectric constant value when the frequency approaches 0 infinitely; is the dipole autocorrelation function; t For time.

[0069] Define the relaxation strength Δ ε = ε r - ε ∞, which characterizes the contribution of atomic polarization and dipole polarization to the dielectric constant and is therefore only related to the dipole moment:

[0070]

[0071] Among them, M (0) 2 > is the mean square dipole moment of the dipoles in the system; < M (0)> 2 is the square of the average dipole moment of the dipoles in the system; V is the volume of the system; ε 0 is the dielectric constant of vacuum; k B is the Boltzmann constant; T is the system temperature. Based on the above formula, we can get ε-f Δ in the relationship ε From this, we can derive the component of dipole polarization phenomenon in the dielectric constant.

[0072] Molecular dynamics simulations were used to calculate the dielectric parameters of the crystalline and amorphous regions of the polyolefin insulation material. This provides a parameter basis for studying the electric field distribution characteristics within the crystalline and amorphous regions of the polyolefin insulation material and at their interfaces under an AC field. During the experiments, the dielectric constants of the crystalline and amorphous regions of the polyolefin insulation material were calculated to be 2.37 and 2.22, respectively.

[0073] Traditional analyses of the crystalline and amorphous regions within cable insulation materials are qualitative. However, the molecular dynamics simulation calculations in this embodiment, by studying their intrinsic dielectric properties, calculate the relevant dielectric performance parameters of the two structures, providing new ideas and methods for quantitatively studying the differences in dielectric properties of their microstructures.

[0074] S3: Importing the heterogeneous structural geometric model, the dielectric parameters of the crystalline region, and the dielectric parameters of the amorphous region into simulation software for simulation calculation to obtain the electric field distribution result of the insulating layer.

[0075] In this example, the inhomogeneous geometric model and dielectric parameters of the insulation layer are imported into COMSOL multiphysics simulation software for simulation calculations. This results in the electric field distribution within the insulation layer of a high-voltage AC extruded insulated cable. The electric field distribution is a graph that depicts the electric field magnitude at various locations within the insulation layer, distinguished by color.

[0076] like Figure 8As shown, S3 can include: importing the heterogeneous structural geometry model, the dielectric parameters of the crystalline region, and the dielectric parameters of the amorphous region; setting boundary conditions and meshing the heterogeneous structural geometry model; and performing simulation calculations to obtain the electric field distribution inside the insulating layer under an AC field. The meshing process is automatically completed by the multiphysics simulation software.

[0077] The boundary conditions include electric potential, and setting the boundary conditions may include: setting the upper end of the heterogeneous structure geometric model to high voltage and the lower end to ground, and the average AC electric field strength applied may be 150 kV / mm. Figure 9 Schematic diagram of the electric field distribution in the crystalline and amorphous regions inside polyolefin insulation material.

[0078] The simulation method under the physical field conditions of this embodiment can effectively simulate and calculate the distribution results of the internal electric field of the high-voltage AC extruded insulated cable.

[0079] Based on the heterogeneous structure of the high-voltage AC cable insulation material, this embodiment constructs a heterogeneous structural geometric model with a similar structure, and constructs molecular structure models of the crystalline region and amorphous region inside the cable insulation material respectively. The intrinsic dielectric properties are studied by means of molecular dynamics simulation calculations, and the relevant dielectric performance parameters of the two-part structure are calculated. The heterogeneous structural geometric model and dielectric parameters are imported into multi-physics field simulation software for simulation calculations to obtain the distribution results of the electric field inside the high-voltage AC extruded insulated cable. The construction of the heterogeneous structural geometric model visualizes the heterogeneous structure of the polyolefin insulation material. The molecular dynamics simulation calculation obtains the difference in the intrinsic dielectric properties of the crystalline region and the amorphous region. The physical field simulation calculation obtains the electric field distribution law inside the high-voltage cable insulation layer. This method provides theoretical guidance and model support for the study of the electric field characteristics of high-voltage AC extruded insulated cables.

[0080] Example 2:

[0081] This embodiment is used to provide a calculation system for the electric field distribution of high-voltage AC extruded insulated cables. Figure 10 As shown, the computing system includes:

[0082] The geometric model building module M1 is used to build a non-homogeneous structural geometric model of the insulation layer of the high-voltage AC extruded insulated cable;

[0083] a dielectric parameter calculation module M2, configured to construct a first molecular structure model of the crystalline region of the insulating layer and a second molecular structure model of the amorphous region of the insulating layer, respectively; perform molecular dynamics simulation calculations based on the first molecular structure model to obtain dielectric parameters of the crystalline region; and perform molecular dynamics simulation calculations based on the second molecular structure model to obtain dielectric parameters of the amorphous region;

[0084] The simulation calculation module M3 is used to import the inhomogeneous structural geometric model, the dielectric parameters of the crystalline region and the dielectric parameters of the amorphous region into simulation software for simulation calculation to obtain the electric field distribution result of the insulating layer.

[0085] Each embodiment in this specification focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0086] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A method for calculating the electric field distribution of a high-voltage AC extruded insulated cable, characterized in that: The calculation method includes: Construct a non-homogeneous structural geometric model of the insulation layer of a high-voltage AC extruded insulated cable; Constructing a first molecular structure model of the crystalline region of the insulating layer and a second molecular structure model of the amorphous region of the insulating layer respectively; performing molecular dynamics simulation calculations based on the first molecular structure model to obtain dielectric parameters of the crystalline region; and performing molecular dynamics simulation calculations based on the second molecular structure model to obtain dielectric parameters of the amorphous region; The inhomogeneous structural geometric model, the dielectric parameters of the crystalline region, and the dielectric parameters of the amorphous region are imported into simulation software for simulation calculation to obtain the electric field distribution result of the insulating layer.

2. The calculation method according to claim 1, characterized in that The construction of the heterogeneous structural geometric model of the insulation layer of the high-voltage AC extruded insulated cable specifically includes: Make samples of insulation layer of high voltage AC extruded insulated cable; Testing the sample to determine the size of the sample, the number of spherulites in the sample, and the volume ratio of the crystalline region to the amorphous region in the sample; the size includes length and width; The boundary of the heterogeneous structure geometric model is drawn according to the size, and a plurality of Voronoi seed points are randomly set within the boundary to generate a Voronoi diagram; the crystalline region and the amorphous region are filled in each Voronoi polygon in the Voronoi diagram according to the volume ratio to obtain the heterogeneous structure geometric model; the number of the Voronoi seed points is the same as the number of the spherulites; and the amorphous region filled in the Voronoi polygon is arranged around the crystalline region filled in the Voronoi polygon.

3. The calculation method according to claim 1, characterized in that The respectively constructing the first molecular structure model of the crystalline region of the insulating layer and the second molecular structure model of the amorphous region of the insulating layer specifically includes: drawing a first molecular chain in a crystalline region of the insulating layer and a second molecular chain in an amorphous region of the insulating layer respectively; Performing geometric optimization on the first molecular chain to obtain a first optimized molecular chain; performing geometric optimization on the second molecular chain to obtain a second optimized molecular chain; Periodically filling the unit cell with the first optimized molecular chain to obtain a first initial molecular structure model; periodically filling the unit cell with the second optimized molecular chain to obtain a second initial molecular structure model; Performing energy optimization on the first initial molecular structure model to obtain a first intermediate molecular structure model; performing energy optimization on the second initial molecular structure model to obtain a second intermediate molecular structure model; The first intermediate molecular structure model is subjected to geometric model optimization to obtain the first molecular structure model of the crystalline region; the second intermediate molecular structure model is subjected to geometric model optimization to obtain the second molecular structure model of the amorphous region.

4. The calculation method according to claim 3, characterized in that The geometric model optimization of the first intermediate molecular structure model specifically includes: firstly performing multiple cycles of annealing treatment on the first intermediate molecular structure model using an isothermal and isobaric ensemble, and then performing annealing treatment using an isothermal and isovolumetric ensemble.

5. The calculation method according to claim 1, characterized in that The molecular dynamics simulation calculation based on the first molecular structure model to obtain the dielectric parameters of the crystal region specifically includes: Performing molecular dynamics simulation calculations based on the first molecular structure model to obtain a dipole autocorrelation function of the crystal region; Calculating the frequency-dependent dielectric constant of the crystal region based on the dipole autocorrelation function of the crystal region; the frequency-dependent dielectric constant is a function of the dielectric constant varying with frequency; The dielectric constant of the crystal region is determined according to the frequency-dependent dielectric constant of the crystal region; the dielectric constant is the dielectric parameter.

6. The calculation method according to claim 5, characterized in that The dipole autocorrelation function is: ； in, is the dipole autocorrelation function; t For time; M (0) is the molecular chain dipole moment at the initial moment; M ( t )for t The molecular chain dipole moment at that moment.

7. The calculation method according to claim 5, characterized in that: Calculating the frequency-dependent dielectric constant of the crystal region based on the dipole autocorrelation function of the crystal region specifically includes: calculating the frequency-dependent dielectric constant of the crystal region based on the dipole autocorrelation function of the crystal region using a correlation relationship between the frequency-dependent dielectric constant and the dipole autocorrelation function; The association relationship is: in, is the frequency-dependent dielectric constant, representing the frequency The dielectric constant under ; is the optical frequency dielectric constant; is the static dielectric constant; is the dipole autocorrelation function; t For time.

8. The calculation method according to claim 5, characterized in that After obtaining the dipole autocorrelation function of the crystal region, the calculation method further includes: calculating the relaxation intensity; The calculation formula of the relaxation strength is: Among them, Δ ε is the relaxation strength; M (0) 2 > is the mean square dipole moment of the dipoles in the system; < M (0)> 2 is the square of the average dipole moment of the dipoles in the system; V is the volume of the system; ε 0 is the dielectric constant of vacuum; k B is the Boltzmann constant; T is the system temperature.

9. The calculation method according to claim 1, characterized in that: The step of importing the heterogeneous structural geometric model, the dielectric parameters of the crystalline region, and the dielectric parameters of the amorphous region into simulation software for simulation calculation to obtain the electric field distribution result of the insulating layer specifically includes: Importing the heterogeneous structural geometric model, the dielectric parameters of the crystalline region, and the dielectric parameters of the amorphous region; Setting boundary conditions and performing meshing on the heterogeneous structural geometric model; A simulation calculation is performed to obtain the electric field distribution result of the insulating layer.

10. A system for calculating the electric field distribution of a high-voltage AC extruded insulated cable, characterized in that: The computing system includes: A geometric model building module is used to build a non-homogeneous structural geometric model of the insulation layer of a high-voltage AC extruded insulated cable; a dielectric parameter calculation module, configured to respectively construct a first molecular structure model of the crystalline region of the insulating layer and a second molecular structure model of the amorphous region of the insulating layer; perform molecular dynamics simulation calculations based on the first molecular structure model to obtain dielectric parameters of the crystalline region; and perform molecular dynamics simulation calculations based on the second molecular structure model to obtain dielectric parameters of the amorphous region; The simulation calculation module is used to import the inhomogeneous structural geometric model, the dielectric parameters of the crystalline region and the dielectric parameters of the amorphous region into simulation software for simulation calculation to obtain the electric field distribution result of the insulating layer.

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