Calculation Method and System for Structural Failure of Ultra-High Voltage and Extra-High Voltage Transformer Bushings under Arc Fault

Abstract

The present invention belongs to the field of non-electrical quantity protection of power system transformers, and discloses a calculation method and system for the structural failure of ultra-high voltage and extra-high voltage transformer bushings under arc faults. In the virtual model of the present invention, the internal oil pressure, temperature and structural deformation of the bushing can be obtained without damaging the physical object, reducing equipment scrapping and environmental pollution. Through the coupling of multiple physical fields - simultaneous solution of fluid dynamics and solid mechanics, the present invention can accurately obtain the internal oil pressure distribution, thermal expansion and mechanical strength change process of the bushing; combined with the structural failure criterion, it can more objectively evaluate the reliability of the bushing against arc shock. The present invention not only greatly reduces the safety and environmental risks of high-voltage arc fault tests, but also has significant advantages in terms of cost, efficiency and reliability, providing strong technical support for the design verification and optimization of ultra-high voltage and extra-high voltage transformer bushings.

Description

Technical Field

[0001] The present invention belongs to the field of non-electrical quantity protection of power system transformers, and particularly relates to a calculation method and system for the structural failure of ultra-high voltage and extra-high voltage transformer bushings under arc faults. Background Art

[0002] Ultra-high voltage and extra-high voltage transformers are key equipment in the power system, and the bushings, as important components, undertake the dual tasks of electrical and mechanical isolation. When the electric field strength borne by the insulating oil inside the bushing exceeds its dielectric strength, it is extremely easy to break down and generate high-energy arcs, and the local high temperature causes the phase change of the insulating oil. This leads to a sharp increase in the internal pressure of the bubbles, and their volume expands, squeezing the surrounding insulating oil and causing a sharp rise in the oil pressure. If this pressure fails to be effectively released, the bushing may rupture, leading to the shutdown of the transformer and even serious consequences such as secondary fires. Therefore, clarifying the anti-explosion performance of the bushing is crucial for preventing transformer accidents. However, there is still uncertainty about whether traditional oil-paper insulated bushings have fire and explosion prevention performance. Given that conducting arc fault tests on transformer bushings involves relatively high safety risks, the research method based on theoretical modeling and numerical simulation has become an efficient and economical alternative for studying internal arc faults in transformer bushings and their damage mechanisms. Summary of the Invention

[0003] The purpose of the present invention is to overcome the safety risks involved in conducting arc fault tests on transformer bushings, and provide a calculation method and system for the structural failure of ultra-high voltage and extra-high voltage transformer bushings under arc faults.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] In the first aspect, the present invention provides a calculation method for the structural failure of ultra-high voltage and extra-high voltage transformer bushings under arc faults, including the following steps:

[0006] Construct a three-dimensional geometric model based on the ultra-high voltage and extra-high voltage transformer bushing;

[0007] Import the three-dimensional geometric model into a finite element analysis model to generate a simulation network model;

[0008] Configure a solver and a solution model for the insulating oil fluid domain of the simulation network model according to requirements;

[0009] Configure a solution model and a structural failure criterion for the transformer bushing solid domain of the simulation network model according to requirements;

[0010] Perform multi-physics field coupling calculations on the solver and solution model of the insulating oil fluid domain and the solution model and structural failure criterion of the transformer bushing solid domain to obtain the internal oil pressure change and structural deformation process of the transformer bushing.

[0011] A further improvement of the present invention lies in that the specific method for constructing a three-dimensional geometric model based on the ultra-high voltage and extra-high voltage transformer bushing is as follows:

[0012] Use SolidWorks to establish a 1:1 equivalent three-dimensional geometric model based on the ultra-high voltage and extra-high voltage transformer bushing.

[0013] A further improvement of the present invention lies in that the specific method for importing the three-dimensional geometric model into the finite element analysis model to generate a simulation network model is as follows:

[0014] Import the three-dimensional geometric model into the finite element analysis model;

[0015] Based on the three-dimensional geometric model, the finite element analysis model uses a curvature size function with flexible meshing ability to generate a simulation network model suitable for simulation calculations in irregular regions.

[0016] A further improvement of the present invention lies in that, according to requirements, configure the insulating oil fluid domain solver and the solution model for the simulation network model. The insulating oil fluid domain solver is a transient pressure-based solver, and the transient pressure-based solver solves by combining the pressure field and velocity field of the fluid domain with the movement of the arc fault-induced bubble boundary, specifically as follows:

[0017]

[0018] Wherein, R represents the radius of the bubble, represents the normal velocity of the bubble surface, represents the normal acceleration of the bubble surface; P d represents the pressure of the fluid domain boundary, represents the specific heat ratio, c represents the watershed boundary, W arc represents the arc energy, W l represents the work done by the bubble during expansion, represents the density of the insulating oil, represents the heat transfer coefficient, represents the bubble volume.

[0019] A further improvement of the present invention lies in that, according to requirements, configure the insulating oil fluid domain solver and the solution model for the simulation network model. The specific solution model is as follows:

[0020] Set the solution model of the insulating oil fluid domain to SST k - Model:

[0021]

[0022]

[0023] Among them, k represents the turbulent kinetic energy, is the time variable, U j represents the velocity component in the j direction, j represents the turbulent direction, is the turbulent direction j of the coordinate variable, P k represents the generation term of the turbulent kinetic energy, represents the specific dissipation rate, v represents the molecular viscosity coefficient, v t represents the turbulent viscosity coefficient, represents the Prandtl number related to the turbulent kinetic energy equation, represents the Prandtl number related to the specific dissipation rate equation, S represents the strain rate tensor, is a constant that affects the dissipation term in the turbulent frequency equation, represents controlling the turbulent kinetic energy k and the constant that controls the interaction between the turbulent frequency, represents the correction constant of, represents the constant related to the dissipation and transport processes of the turbulent frequency, F 1 represents the mixing function, F 1 is used for SST k - to smoothly transition between the near-wall and free-stream regions in the model.

[0024] A further improvement of the present invention lies in that, according to requirements, a solution model for the solid domain of the transformer bushing and a structural failure criterion are configured for the simulation network model. The specific method for configuring the solution model for the solid domain of the transformer bushing is as follows:

[0025] Use the balance equation to describe the force balance conditions at various locations inside the transformer bushing under a fault impact. The calculation formula is:

[0026]

[0027] In the formula, represents the stress component acting along the node direction at the f i represents the body force component of the node, x j represents thej Position vector;

[0028] Based on the strain-displacement relationship, the strain is calculated through the displacement gradient to describe the deformation of the material. The calculation formula is:

[0029]

[0030] In the formula, represents the strain component acting along the node in the direction of node , x i represents the position vector of node i , u i represents the displacement component of node i , u j represents the displacement component of node j ;

[0031] For isotropic materials, the relationship between stress and strain is used as the solution model. The calculation formula is:

[0032]

[0033]

[0034]

[0035] In the formula, represents the normal stress in the x direction, represents the normal stress in the y direction, represents the strain in the x direction, represents the strain in the y direction, represents the shear stress in the x and y directions, represents the shear strain, v represents the Poisson's ratio, G represents the shear modulus, E represents the Young's modulus.

[0036] A further improvement of the present invention lies in that, according to requirements, in configuring the solution model and the structural failure criterion for the solid domain of the transformer bushing in the simulation network model, the specific method for configuring the structural failure criterion for the solid domain of the transformer bushing is as follows:

[0037] The structural failure criterion is used to determine whether the transformer bushing material has fractured. The calculation formula is:

[0038]

[0039] In the formula, represents the failure strain, represents the equivalent plastic strain, , , respectively represent the principal strains in the x, y, and z directions.

[0040] A further improvement of the present invention lies in performing multi - physical - field coupling calculations on the solver and solution model of the insulating oil fluid domain and the solution model and structural failure criterion of the transformer bushing solid domain. The specific method for obtaining the internal oil pressure change and structural deformation process of the transformer bushing is as follows:

[0041] The conduction of displacement and stress data between the insulating oil fluid domain and the transformer bushing solid domain satisfies:

[0042]

[0043]

[0044] In the formula, represents the stress of the insulating oil fluid domain, represents the stress of the transformer bushing solid domain, represents the normal vector of the insulating oil fluid domain, represents the normal vector of the transformer bushing solid domain, represents the displacement of the insulating oil fluid domain, represents the displacement of the transformer bushing solid domain.

[0045] In a second aspect, the present invention provides an ultra - high and extra - high voltage transformer bushing structural failure calculation system under arc fault, including:

[0046] A model construction module for constructing a three - dimensional geometric model according to the ultra - high and extra - high voltage transformer bushing;

[0047] A simulation model generation module for importing the three - dimensional geometric model into a finite - element analysis model to generate a simulation network model;

[0048] A fluid domain solution module for configuring a solver and solution model for the insulating oil fluid domain of the simulation network model according to requirements;

[0049] A solid domain solution module for configuring a solution model and structural failure criterion for the transformer bushing solid domain of the simulation network model according to requirements;

[0050] A coupling module for performing multi - physical - field coupling calculations on the solver and solution model of the insulating oil fluid domain and the solution model and structural failure criterion of the transformer bushing solid domain to obtain the internal oil pressure change and structural deformation process of the transformer bushing.

[0051] In a third aspect, the present invention provides an electronic device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the steps of the calculation method for the structural failure of ultra-high voltage and extra-high voltage transformer bushings under arc faults are implemented.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] In the virtual model of the present invention, the internal oil pressure, temperature, and structural deformation of the bushing can be obtained without damaging the physical object, reducing equipment scrapping and environmental pollution. Through the coupling of multiple physical fields - simultaneous solution of fluid dynamics and solid mechanics, the present invention can accurately obtain the internal oil pressure distribution, thermal expansion, and mechanical strength change process of the bushing; combined with the structural failure criterion, it can more objectively evaluate the reliability of the bushing against arc shock. The present invention not only greatly reduces the safety and environmental risks of high-voltage arc fault tests, but also has significant advantages in terms of cost, efficiency, and reliability, providing strong technical support for the design verification and optimization of ultra-high voltage and extra-high voltage transformer bushings. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 is a flowchart of the present invention;

[0055] Figure 2 is a system diagram of the present invention;

[0056] Figure 3 is a geometric model diagram of ultra-high voltage and extra-high voltage transformer bushings in the present invention;

[0057] Figure 4 is a mesh division diagram of ultra-high voltage and extra-high voltage transformer bushings in the present invention;

[0058] Figure 5 is a calculation flowchart of Example 3;

[0059] Figure 6 is a distribution diagram of the internal oil pressure of ultra-high voltage and extra-high voltage transformer bushings;

[0060] Figure 7 is a distribution diagram of the structural strain of ultra-high voltage and extra-high voltage transformer bushings;

[0061] Figure 8 is a system diagram of Example 4. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0062] To further understand the content of the present invention, the following describes the present invention in detail with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments are only for explaining the present invention and not for limiting it.

[0063] Example 1:

[0064] Refer to Figure 1, A calculation method for the structural failure of UHV and EHV transformer bushings under arc faults, comprising the following steps:

[0065] S1, Construct a three-dimensional geometric model based on the UHV and EHV transformer bushings.

[0066] S2, Import the three-dimensional geometric model into the finite element analysis model to generate a simulation network model.

[0067] S3, Configure the solver and solution model for the insulating oil fluid domain of the simulation network model according to requirements.

[0068] S4, Configure the solution model and structural failure criterion for the solid domain of the transformer bushing in the simulation network model according to requirements.

[0069] S5, Perform multi-physics field coupling calculations on the solver and solution model of the insulating oil fluid domain and the solution model and structural failure criterion of the solid domain of the transformer bushing to obtain the internal oil pressure change and structural deformation process of the transformer bushing.

[0070] Example 2:

[0071] See Figure 2 , A calculation system for the structural failure of UHV and EHV transformer bushings under arc faults, comprising:

[0072] A model construction module for constructing a three-dimensional geometric model based on the UHV and EHV transformer bushings;

[0073] A simulation model generation module for importing the three-dimensional geometric model into the finite element analysis model to generate a simulation network model;

[0074] A fluid domain solution module for configuring the solver and solution model for the insulating oil fluid domain of the simulation network model according to requirements;

[0075] A solid domain solution module for configuring the solution model and structural failure criterion for the solid domain of the transformer bushing in the simulation network model according to requirements;

[0076] A coupling module for performing multi-physics field coupling calculations on the solver and solution model of the insulating oil fluid domain and the solution model and structural failure criterion of the solid domain of the transformer bushing to obtain the internal oil pressure change and structural deformation process of the transformer bushing.

[0077] Example 3:

[0078] See Figure 3 and Figure 4 , Taking a UHV and EHV transformer bushing with a diameter of 140 mm and a height of 1560 mm as the research object, the transformer bushing is an oil-paper insulated oil bushing, and the outer wall material is fiberglass.

[0079] The calculation method for the structural failure of UHV and EHV transformer bushings under arc faults in this embodiment includes the following steps:

[0080] Step 1: Use SolidWorks to establish a 1:1 equivalent 3D simulation model of UHV and EHV transformer bushings.

[0081] Step 2: Import the 3D simulation model of UHV and EHV transformer bushings into ANSYS software.

[0082] Step 3: Adopt the Curvature Size Function with flexible meshing ability to generate a high-quality simulation mesh model suitable for simulation calculations in irregular regions.

[0083] Step 4: Set the solver for the high-quality simulation mesh model. The solver for the high-quality simulation mesh model is the transient pressure-based solver.

[0084] Step 5: Solve the pressure field and velocity field in the fluid domain based on the movement of the bubble boundary induced by arc faults. This boundary movement follows the bubble dynamics equation, and the calculation formula is:

[0085]

[0086] In the formula, R represents the radius of the bubble, represents the normal velocity of the bubble surface, represents the normal acceleration of the bubble surface; P d represents the pressure on the fluid domain boundary, represents the specific heat ratio, c represents the watershed boundary, W arc represents the arc energy, W l represents the work done by the bubble during expansion.

[0087] Step 6: Set the solution model for the insulating oil fluid domain as the SST k - Model:

[0088]

[0089]

[0090] In the formula, k represents the turbulent kinetic energy, is the time variable, U j represents the velocity component in the j direction, j represents the turbulent direction, is the turbulent flow direction j of the coordinate variable, P k represents the generation term of turbulent kinetic energy, represents the specific dissipation rate, v represents the molecular viscosity coefficient, v t represents the turbulent viscosity coefficient, represents the Prandtl number related to the turbulent kinetic energy equation, represents the Prandtl number related to the specific dissipation rate equation, S represents the strain rate tensor, is the constant affecting the dissipation term in the turbulent frequency equation, represents controlling the turbulent kinetic energy k and the constant governing the interaction between the turbulent frequency, represents the correction constant of, represents the constant related to the dissipation and transport processes of the turbulent frequency, F 1 represents the blending function, F 1 is used for SST k - to smoothly transition the model between the near-wall and free-stream regions.

[0091] In the solution model of the insulating oil fluid domain, the transient fluid field is updated using a moving mesh, and the calculation formula is:

[0092]

[0093] where, is the density, is the volume variable, is the control volume boundary, u is the velocity vector, u g is the mesh velocity of the moving mesh, is the area vector, Γ is the diffusion coefficient, is the internal heat source gradient of, represents the internal heat source source term of.

[0094] Among them, the update of the moving mesh adopts the spring smoothing model:

[0095]

[0096] where, F i represents the total spring force vector i experienced by the node k ijis the spring stiffness coefficient (or weight) connecting node i and node j The spring stiffness coefficient (or weight) between two nodes is usually inversely proportional to the distance between the two nodes, indicating the influence of the relative position change between the two nodes on the mesh deformation. x i and x j are the position vectors of node i and node j respectively. N is the number of nodes adjacent to node i

[0097] Step 7: Use the equilibrium equation to describe the force balance conditions at various locations inside the transformer bushing under a fault impact. The calculation formula is:

[0098]

[0099] In the formula, represents the stress component acting on node along the direction of node f i represents the body force component of node x j represents the position vector of node j

[0100] Based on the strain-displacement relationship, the strain is calculated through the displacement gradient to describe the deformation of the material. The calculation formula is:

[0101]

[0102] In the formula, represents the strain component acting on node along the direction of node x i represents the position vector of node i u i represents the displacement component of node i u j represents the displacement component of node j

[0103] For an isotropic material, the relationship between stress and strain is used as the solution model. The calculation formula is:

[0104]

[0105]

[0106]

[0107] In the formula, represents the normal stress in the x direction, represents the normal stress in the y direction, represents the strain in the x direction, represents the strain in the y direction, represents the shear stress in the x and y directions, represents the shear strain, v represents the Poisson's ratio, G represents the shear modulus, E represents the Young's modulus.

[0108] Step 8: The structural failure criterion is used to determine whether the transformer bushing material fails, and the calculation formula is:

[0109]

[0110] In the formula, represents the failure strain, represents the equivalent plastic strain, , , respectively represent the principal strains in the x, y, and z directions.

[0111] Step 9: The conduction of data on displacement and force between the insulating oil fluid domain and the transformer bushing solid domain satisfies:

[0112]

[0113]

[0114] In the formula, represents the stress of the insulating oil fluid domain, represents the stress of the transformer bushing solid domain, represents the normal vector of the insulating oil fluid domain, represents the normal vector of the transformer bushing solid domain, represents the displacement of the insulating oil fluid domain, represents the displacement of the transformer bushing solid domain.

[0115] Step 10: When the residuals of force and displacement between the insulating oil fluid domain and the transformer bushing solid domain reach the required value within a time step, output the change in the internal oil pressure of the bushing and the results of structural deformation at this time step.

[0116] Through multi-physical field coupling modeling and simulation calculations, the present invention successfully simulates the oil pressure change and structural deformation process of ultra-high and extra-high voltage transformer bushings under arc fault conditions. This method effectively reproduces the sharp rise in oil pressure caused by arc faults and its impact on the bushing structure, providing important theoretical support for in-depth understanding of the dynamic process of oil pressure shock and structural deformation, and further providing a solid data basis for quantifying the increase in insulating oil pressure and the explosion-proof performance of bushings.

[0117] Figure 6 and Figure 7 respectively show the simulation calculation results in specific embodiments of the present invention. Figure 7 is the internal oil pressure distribution diagram of ultra-high and extra-high voltage transformer bushings, Figure 8 is the structural strain distribution diagram of ultra-high and extra-high voltage transformer bushings. It can be seen from Figure 7 that with the occurrence of arc faults, the internal oil pressure of the bushing gradually increases, especially significant pressure concentration is formed near the top and bottom of the bushing, and the peak oil pressure reaches 1.6 MPa. This characteristic of pressure increase reveals the phenomenon that the local high temperature induced by arc faults causes the insulating oil to vaporize, and the expansion of bubbles leads to a rapid rise in oil pressure. Figure 4 shows the stress distribution of the bushing under the action of oil pressure. As the fault evolves, the stress inside the bushing gradually increases, especially obvious stress concentration appears in the bottom area, and the maximum stress exceeds 100 MPa, ultimately leading to material damage and structural failure. The above calculation results show that the high oil pressure caused by arc faults poses a serious threat to the mechanical strength of the bushing, especially in the bottom area, where stress failure is likely to occur. These simulation results provide a solid theoretical basis for in-depth understanding of the damage mechanism of ultra-high voltage and extra-high voltage transformer bushings under arc faults and for further optimizing the protection design.

[0118] Embodiment 4:

[0119] Please refer to Figure 8 as shown, the present invention also provides an electronic device 100 for calculating the structural failure of ultra-high and extra-high voltage transformer bushings under arc faults; the electronic device 100 includes a memory 101, at least one processor 102, a computer program 103 stored in the memory 101 and executable on the at least one processor 102, and at least one communication bus 104.

[0120] The memory 101 can be used to store the computer program 103. By running or executing the computer program stored in the memory 101 and invoking the data stored in the memory 101, the processor 102 implements the steps of the calculation method for the structural failure of ultra-high and extra-high voltage transformer bushings under arc faults described in Embodiment 1. The memory 101 may mainly include 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 (such as a sound playback function, an image playback function, etc.); the data storage area can store data created according to the use of the electronic device 100 (such as audio data, etc.). In addition, the memory 101 may include non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, at least one magnetic disk storage device, a flash memory device, or other non-volatile solid-state storage devices.

[0121] The at least one processor 102 can be a Central Processing Unit (CPU), or can 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 processor 102 can be a microprocessor or the processor 102 can also be any conventional processor, etc. The processor 102 is the control center of the electronic device 100, and connects various parts of the entire electronic device 100 using various interfaces and lines.

[0122] The memory 101 in the electronic device 100 stores multiple instructions to implement the calculation method for the structural failure of ultra-high and extra-high voltage transformer bushings under arc faults. The processor 102 can execute the multiple instructions to thereby implement:

[0123] Construct a three-dimensional geometric model according to the ultra-high and extra-high voltage transformer bushing;

[0124] Import the three-dimensional geometric model into a finite element analysis model to generate a simulation network model;

[0125] Configure a solver and a solution model for the insulating oil fluid domain of the simulation network model according to requirements;

[0126] According to requirements, configure the solution model and structural failure criterion for the solid domain of the transformer bushing in the simulation network model;

[0127] Perform multi-physics field coupling calculations on the solver and solution model of the insulating oil fluid domain and the solution model and structural failure criterion of the solid domain of the transformer bushing to obtain the internal oil pressure change and structural deformation process of the transformer bushing.

[0128] Embodiment 5

[0129] If the modules / units integrated in the electronic device 100 are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, to implement all or part of the processes in the above embodiment methods of the present invention, it can also be completed by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above various method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file, or some intermediate form, etc. The computer-readable medium can include: any entity or device that can carry the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disc, computer memory, and read-only memory (ROM, Read-Only Memory).

[0130] Those skilled in the art should understand that the embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0131] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of processes and / or blocks in the flowchart and / or block diagram can also be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in one Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0132] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to work in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction device that implements the functions specified in one or more processes and / or blocks Figure 1 of the process or processes and / or boxes Figure 1 or boxes specified.

[0133] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus, so that a series of operation steps are executed on the computer or other programmable apparatus to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one or more processes and / or blocks Figure 1 of the process or processes and / or boxes Figure 1 or boxes specified.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent substitutions can still be made to the specific embodiments of the present invention, and any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. Calculation method for structural failure of ultra-high voltage and extra-high voltage transformer bushings under arc faults, characterized in that, It includes the following steps: Construct a three-dimensional geometric model based on the ultra-high voltage and extra-high voltage transformer bushings; Import the three-dimensional geometric model into the finite element analysis model to generate a simulation network model; According to requirements, configure the solver and solution model for the insulating oil fluid domain of the simulation network model. The insulating oil fluid domain solver is a transient pressure-based solver, and the transient pressure-based solver solves through the fluid domain pressure field and velocity field, combined with the movement of the arc fault-induced bubble boundary, as follows: Among them, R represents the radius of the bubble, represents the normal velocity of the bubble surface, represents the normal acceleration of the bubble surface; P d represents the pressure at the fluid domain boundary, represents the specific heat ratio, c represents the watershed boundary, W arc represents the arc energy, W l represents the work done by the bubble during expansion, represents the density of insulating oil, represents the heat transfer coefficient, represents the bubble volume; The solution model is as follows: Set the solution model of the insulating oil fluid domain to SST k - Model: Among them, k represents the turbulent kinetic energy, is the time variable, U j represents the direction j of the velocity component, j represents the turbulent direction, is the turbulent direction j of the coordinate variable, P k represents the generation term of the turbulent kinetic energy, represents the specific dissipation rate, v represents the molecular viscosity coefficient, v t represents the turbulent viscosity coefficient, represents the Prandtl number related to the turbulent kinetic energy equation, represents the Prandtl number related to the specific dissipation rate equation, S represents the strain rate tensor, is a constant affecting the dissipation term in the turbulent frequency equation, represents controlling the turbulent kinetic energy k and the constant for the interaction between the turbulent frequency, represents of the correction constant, represents the constant related to the dissipation and transport processes of the turbulent frequency, F 1 represents the mixing function, F 1 is used for SST k - to smoothly transition between the near-wall and free-stream regions in the model; According to requirements, configure the solution model and structural failure criterion for the transformer bushing solid domain of the simulation network model. The specific method for configuring the solution model of the transformer bushing solid domain is as follows: Use the equilibrium equation to describe the force balance conditions at various locations inside the transformer bushing under fault impact. The calculation formula is: In the formula, denotes the stress component acting along the node in the direction of the node ; f i denotes the body force component of the node ; x j denotes the position vector of the node j . Based on the strain-displacement relationship, calculate the strain through the displacement gradient to describe the deformation of the material. The calculation formula is: In the formula, represents the node The strain component acting along the node direction, x i represents the position vector of the node i ; u i represents the displacement component of the node i ; u j represents the displacement component of the node j ; For isotropic materials, the relationship between stress and strain is used as the solution model. The calculation formula is: In the formula, represents the normal stress in the x direction, represents the normal stress in the y direction, represents the strain in the x direction, represents the strain in the y direction, represents the shear stress in the x and y directions, represents the shear strain, v represents the Poisson's ratio, G represents the shear modulus, E represents the Young's modulus; Perform multi-physics field coupling calculations on the solver and solution model of the insulating oil fluid domain and the solution model and structural failure criterion of the transformer bushing solid domain to obtain the internal oil pressure change and structural deformation process of the transformer bushing.

2. The calculation method for the structural failure of ultra-high voltage and extra-high voltage transformer bushings under arc faults according to claim 1, characterized in that The specific method for constructing a three-dimensional geometric model based on the ultra-high voltage and extra-high voltage transformer bushings is as follows: Use SolidWorks to establish a 1:1 equivalent three-dimensional geometric model based on the ultra-high voltage and extra-high voltage transformer bushings.

3. The calculation method for the structural failure of ultra-high voltage and extra-high voltage transformer bushings under arc faults according to claim 1, wherein The specific method for importing the three-dimensional geometric model into the finite element analysis model to generate a simulation network model is as follows: Import the three-dimensional geometric model into the finite element analysis model; The finite element analysis model is based on the three-dimensional geometric model and uses a curvature size function with flexible meshing ability to generate a simulation network model suitable for simulation calculations in irregular regions.

4. The calculation method for the structural failure of ultra-high voltage and extra-high voltage transformer bushings under arc faults according to claim 1, wherein In configuring the solution model and structural failure criterion for the transformer bushing solid domain of the simulation network model according to requirements, the specific method for configuring the structural failure criterion of the transformer bushing solid domain is as follows: The structural failure criterion is used to determine whether the transformer bushing material has fractured. The calculation formula is: Wherein, represents the failure strain, represents the equivalent plastic strain, , , respectively represent the principal strains in the x, y, and z directions.

5. The calculation method for the structural failure of ultra-high voltage and extra-high voltage transformer bushings under arc faults according to claim 1, characterized in that The specific method for performing multi-physics field coupling calculations on the solver and solution model of the insulating oil fluid domain and the solution model and structural failure criterion of the transformer bushing solid domain to obtain the internal oil pressure change and structural deformation process of the transformer bushing is as follows: The conduction of displacement and stress data between the insulating oil fluid domain and the transformer bushing solid domain satisfies: In the formula, represents the stress of the insulating oil fluid domain, represents the stress of the transformer bushing solid domain, represents the normal vector of the insulating oil fluid domain, represents the normal vector of the transformer bushing solid domain, represents the displacement of the insulating oil fluid domain, represents the displacement of the transformer bushing solid domain.

6. The calculation system for the structural failure of ultra-high voltage and extra-high voltage transformer bushings under arc faults is characterized in that It includes: A model construction module for constructing a three-dimensional geometric model based on the ultra-high voltage and extra-high voltage transformer bushings; A simulation model generation module for importing the three-dimensional geometric model into the finite element analysis model to generate a simulation network model; A fluid domain solver module for configuring the solver and solution model for the insulating oil fluid domain of the simulation network model according to requirements. The insulating oil fluid domain solver is a transient pressure-based solver, and the transient pressure-based solver solves through the fluid domain pressure field and velocity field, combined with the movement of the arc fault-induced bubble boundary, as follows: Among them, R represents the radius of the bubble, represents the normal velocity of the bubble surface, represents the normal acceleration of the bubble surface; P d represents the pressure at the fluid domain boundary, represents the specific heat ratio, c represents the watershed boundary, W arc represents the arc energy, W l represents the work done by the bubble during expansion, represents the density of insulating oil, represents the heat transfer coefficient, represents the bubble volume; The solution model is as follows: Set the solution model of the insulating oil fluid domain to SST k - Model: Among them, k represents the turbulent kinetic energy, is the time variable, U j represents the direction j of the velocity component, j represents the turbulent direction, is the turbulent direction j of the coordinate variable, P k represents the generation term of the turbulent kinetic energy, represents the specific dissipation rate, v represents the molecular viscosity coefficient, v t represents the turbulent viscosity coefficient, represents the Prandtl number related to the turbulent kinetic energy equation, represents the Prandtl number related to the specific dissipation rate equation, S represents the strain rate tensor, is a constant affecting the dissipation term in the turbulent frequency equation, represents controlling the turbulent kinetic energy k and the constant governing the interaction between the turbulent frequency, represents of the correction constant, represents the constant related to the dissipation and transport processes of the turbulent frequency, F 1 represents the blending function, F 1 is used for SST k - model to smoothly transition between the near-wall and free-stream regions; The solid domain solving module is used to configure the solving model and structural failure criterion for the solid domain of the transformer bushing in the simulation network model according to requirements. The specific method for configuring the solving model of the solid domain of the transformer bushing is as follows: Use the equilibrium equation to describe the force balance conditions at various positions inside the transformer bushing under fault impact. The calculation formula is: In the formula, denotes the node The stress component acting along the node direction, f i denotes the node body force component, x j denotes the node j position vector; Based on the strain-displacement relationship, calculate the strain through the displacement gradient to describe the deformation of the material. The calculation formula is: In the formula, represents the strain component acting along the node in the direction of the node ; x i represents the position vector of the node i ; u i represents the displacement component of the node i ; u j represents the displacement component of the node j ; For isotropic materials, the relationship between stress and strain is used as the solving model. The calculation formula is: In the formula, represents the normal stress in the x direction, represents the normal stress in the y direction, represents the strain in the x direction, represents the strain in the y direction, represents the shear stress in the x and y directions, represents the shear strain, v represents the Poisson's ratio, G represents the shear modulus, E represents the Young's modulus; The coupling module is used to perform multi-physical field coupling calculations on the solver and solving model of the insulating oil fluid domain and the solving model and structural failure criterion of the solid domain of the transformer bushing to obtain the internal oil pressure change and structural deformation process of the transformer bushing.

7. An electronic device, comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method for calculating the structural failure of ultra-high and extra-high voltage transformer bushings under arc faults described in any one of claims 1 to 5.

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