Phase field simulation method and device for discharge embrittlement fault of extra-high voltage GIS / GIL post insulator, and storage medium

Abstract

The invention discloses a phase field simulation method and device for an extra-high voltage GIS / GIL post insulator discharge embrittlement fault and a storage medium, and relates to the field of insulator calculation of electric stress-mechanical stress, various parameters of an epoxy resin-aluminum oxide composite material are set, and constitutive parameters are measured and input through a stress test means; establishing geometric models of the post insulator, the high-voltage electrode and the ground electrode; establishing an electric field and stress field coupling model, and selecting a corresponding control equation; and simulating phase field simulation of discharge embrittlement evolution under the mesoscale of the surface of the post insulator to obtain the change conditions and numerical values of the electric field and mechanical stress of the single post insulator in the embrittlement process. According to the method, the problem that the phase field model simulates discharge brittle rupture of the post insulator under the electric stress-mechanical stress coupling effect is considered, and the evolution state and development mechanism of the discharge brittle rupture can be more effectively and accurately represented and predicted.

Description

Technical Field

[0001] The present invention relates to the field of calculating electrical stress-mechanical stress of insulators, and in particular to a phase field simulation method, device and storage medium for discharge brittle fracture fault of ultra-ultra-high voltage GIS / GIL post insulators. Background Art

[0002] Gas-insulated transmission lines / gas-insulated transmission switches (GIL / GIS) have the characteristics of large transmission capacity, low loss, long service life, and long transmission distance, which can effectively adapt to the rapid and sustainable development of clean energy. GIL / GIS equipment is mainly composed of high-voltage conductors, grounding shells, insulators, insulating gas and particulate collectors, among which the high-voltage conductors and grounding shells are made of aluminum alloy, and the insulators are cast from epoxy resin. Insulators are mainly divided into post insulators and basin insulators. Post insulators have the advantages of easy installation, good support, and thermal expansion and mechanical strain compensation, and are irreplaceable in the key parts of GIL / GIS.

[0003] Under the action of complex electrical stress and mechanical stress, post insulators have experienced breakdown and explosion accidents many times during operation, which has brought great safety hazards to the safe and reliable operation of GIL / GIS. Therefore, simulating the brittle fracture behavior of post insulators under the coupling of electrical stress and mechanical stress and clarifying the insulation failure mechanism have important scientific significance and engineering value for the optimal design of insulators and the reliable operation of GIL / GIS. Summary of the invention

[0004] In order to overcome the deficiencies of the above technologies, the present invention provides a method, device and storage medium that take into account the discharge brittle cracking problem of post insulators under the coupling of electrical stress and mechanical stress, so as to more accurately characterize and observe the brittle cracking evolution process of insulators.

[0005] The technical solution adopted by the present invention to overcome the technical problems is:

[0006] A phase field simulation method for discharge brittle fracture fault of ultra-high voltage GIS / GIL post insulators, comprising:

[0007] S1. Set material parameters in COMSOL finite element software;

[0008] S2. Build the geometric model of GIL post insulator in COMSOL finite element software;

[0009] S3. Establish an electric field model in COMSOL finite element software;

[0010] S4. Establish a stress field model in COMSOL finite element software;

[0011] S5. Establish a phase field model in COMSOL finite element software;

[0012] S6. Set the calculation time step and the upper limit of the simulation time, iteratively solve the models in steps S3 to S5 in the region of the post insulator geometric model, and observe the crack development process until the breakdown or the simulation time upper limit is reached;

[0013] S7. Obtain the nearby electric field, phase field, and stress field during the crack development process inside the post insulator, observe and simulate the crack development throughout the evolution process, and compare and verify the simulation results with the time engineering failure.

[0014] Furthermore, in step S1, material parameters used for simulation calculation of epoxy resin-alumina composite material are set in COMSOL finite element software, and the material parameters include: density, Young's modulus, Poisson's ratio, relative dielectric constant, and critical energy release rate.

[0015] Furthermore, in step S1, the stress tensile method is used to detect the epoxy casting sample model to obtain material parameters, and the density is 1200kg / m 3 , Young's modulus is 3 GPa, Poisson's ratio is 0.3, relative dielectric constant is 3.5, and critical energy release rate is 3800 J / m 2 .

[0016] Furthermore, in step S2, a geometric model of a GIL post insulator is constructed in COMSOL finite element software, including a high-voltage electrode, an epoxy resin-alumina casting part, and a ground electrode. An air gap and an initial crack are set on the left side of the post insulator, and the geometric model of the post insulator is meshed. The post insulator is composed of: high-voltage electrode, air gap, initial crack, and ground electrode from top to bottom.

[0017] Further, step S3 includes the following steps:

[0018] S31. Using Maxwell's equations, we can solve the electric field related expressions as follows:

[0019]

[0020] in is the Hamiltonian operator, H is the magnetic induction intensity vector, J is the current density vector, D is the electric displacement vector, E is the electric field intensity vector, B is the magnetic flux density vector, ρ is the charge density, × is the curl operation, · is the divergence operation, is the symbol of partial derivative function, t is time;

[0021] S32. Establish the derivation formula as follows:

[0022]

[0023] Where σ is the conductivity, j is the imaginary operator, ω is the angular frequency, ε is the dielectric constant of the material, is the scalar potential;

[0024] S33. The initial conditions are set as: the high voltage electrode is 500kV and the ground electrode is 0kV.

[0025] Further, step S4 includes the following steps:

[0026] S41. The expression for elastic strain energy of stress field is as follows:

[0027] ψ b =∫ Ω g(φ)ψ + (ε)+ψ - (ε)dΩ

[0028]

[0029] <ε1+ε2+ε3> + =1 / 2((ε1+ε2+ε3)+|ε1+ε2+ε3|)

[0030] <ε1+ε2+ε3> - =1 / 2((ε1+ε2+ε3)-|ε1+ε2+ε3|)

[0031]

[0032] Where Ω is the infinitesimal region of the three-pillar insulator volume integral, g(φ) is the free energy function, ψ + (ε) is the free energy density tensile stress, ψ - (ε) is the free energy density compressive stress, λ and μ are both Lame constants, ε1 is the anisotropic strain in the x direction, ε2 is the anisotropic strain in the y direction, ε3 is the anisotropic strain in the z direction, and |·| is the absolute value.

[0033] Further, step S5 includes the following steps:

[0034] S51. The evolution of the conservative variables at any point i in a phase field simulation over time is defined by the Cahn-Hilliard equation as follows:

[0035]

[0036] Where c i is the i-th conservative variable, M i is the i-th conservative variable c i The kinetic mobility of the system, F is the total free energy functional of the system;

[0037] S52. The evolution of the conservative variables at any point j in the phase field simulation with time is defined by the Allen-Cahn equation as follows:

[0038] Where η j is the jth microstructure unit, L j is the jth microstructure unit η j The kinetic mobility of the energy factors involved;

[0039] S53. When the boundary conditions are fixed, for non-conservative variables, the time derivative of the total free energy functional F of the system is as follows:

[0040]

[0041] Where η is a tiny structural unit, and L is the kinetic mobility of the energy factor contained in the tiny structural unit η; S54. Under fixed boundary conditions, for conservative variables, the total free energy functional F of the system is derived with respect to time as follows:

[0042]

[0043] Where J is the flux vector, J c is the flux vector under conservative variables, M is the kinetic mobility, c is the order variable, J ci For the flux vector under the i-th conservative variable, the equation is established as follows:

[0044] In the formula is the surface integral of the conservative variables, the flux at the boundary is zero, and the equation is:

[0045]

[0046] S55. Starting from the uniform free energy density, Taylor expansion is performed using component derivatives. For the isotropic material used in three-post insulators, the free energy is as follows:

[0047]

[0048] Where f is the free energy, f0(c) is the initial free energy, κ i is the coefficient of the i-th Taylor expansion term, i∈{1,...,n}, and n is the total number of Taylor expansion terms;

[0049] S56. The Cahn-Hilliard free energy functional is established as follows:

[0050]

[0051] Where V is the volume integral, χ is the gradient energy coefficient;

[0052] The free energy functional is established as follows:

[0053]

[0054] Where f local (c i ,η j ) is the local chemical free energy density, is the gradient energy density, f app (c i ,η i ) is the additional energy term,

[0055] γ i is the i-th multidimensional gradient energy evolution coefficient among N conservative field variables, γ j is the j-th multidimensional gradient energy evolution coefficient among the M non-conservative field variables.

[0056] Furthermore, in step S6, the calculation time step is set to 0.2μs, and the upper limit of the simulation time is set to 200μs. On the other hand, the present invention also relates to a phase field simulation device for discharge brittle fracture fault of ultra-high voltage GIS / GIL post insulator, comprising: a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other through the communication bus; wherein:

[0057] The memory is used to store computer programs;

[0058] The processor is configured to execute, by running a program stored in the memory:

[0059] Set material parameters in COMSOL finite element software;

[0060] Build the geometric model of GIL post insulator in COMSOL finite element software;

[0061] Establish an electric field model in COMSOL finite element software;

[0062] Establish a stress field model in COMSOL finite element software;

[0063] Establish a phase field model in COMSOL finite element software;

[0064] Set the calculation time step and simulation time limit, iteratively solve each model in the geometric model area of ​​the post insulator, and observe the crack development process until breakdown or reaching the simulation time limit;

[0065] The nearby electric field, phase field, and stress field during the crack development process inside the post insulator are obtained, the crack development is observed and simulated throughout the evolution process, and the simulation results are compared and verified with time engineering failures.

[0066] On the other hand, the present invention also relates to a computer-readable storage medium, wherein a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the computer program implements:

[0067] Set material parameters in COMSOL finite element software;

[0068] Build the geometric model of GIL post insulator in COMSOL finite element software;

[0069] Establish an electric field model in COMSOL finite element software;

[0070] Establish a stress field model in COMSOL finite element software;

[0071] Establish a phase field model in COMSOL finite element software;

[0072] Set the calculation time step and simulation time limit, iteratively solve each model in the geometric model area of ​​the post insulator, and observe the crack development process until breakdown or reaching the simulation time limit;

[0073] The nearby electric field, phase field, and stress field during the crack development process inside the post insulator are obtained, the crack development is observed and simulated throughout the evolution process, and the simulation results are compared and verified with time engineering failures.

[0074] The beneficial effects of the present invention are as follows: a phase field simulation of the evolution process of insulator brittle cracking under the coupling of electrical stress and mechanical stress is proposed, which can effectively obtain the development law of brittle cracking. Compared with the traditional model, the present invention greatly shortens the calculation time and improves the calculation efficiency. In addition, the implementation process of the present invention is simple, the practicability is strong, and it can be widely promoted. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 is a flow chart of the method of the present invention;

[0076] Figure 2 The initial geometric structure diagram of the post insulator of the present invention;

[0077] Figure 3 A diagram showing the crack evolution process of the post insulator of the present invention;

[0078] Figure 4 This is a diagram of the head electric field and mechanical stress during the crack extension process of the present invention. DETAILED DESCRIPTION

[0079] The following is combined with Figure 1 To Attachment Figure 4 The preferred embodiments of the present invention are described in detail so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0080] In the description of the present invention, it should be noted that the embodiments described in the present invention are part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. The terms "first", "second", etc. in the specification and claims of this article and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, device, product or equipment that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0081] Example 1

[0082] As attached Figure 1 As shown, a phase field simulation method for discharge brittle fracture fault of ultra-high voltage GIS / GIL post insulator includes:

[0083] S1. Set material parameters in COMSOL finite element software.

[0084] S2. Build the geometric model of GIL post insulator in COMSOL finite element software.

[0085] S3. Establish the electric field model in COMSOL finite element software.

[0086] S4. Establish the stress field model in COMSOL finite element software.

[0087] S5. Establish a phase field model in COMSOL finite element software.

[0088] S6. Set the calculation time step and the upper limit of the simulation time, iteratively solve the models in steps S3 to S5 in the geometric model area of ​​the post insulator, and observe the crack development process until breakdown or reaching the upper limit of the simulation time.

[0089] S7. Obtain the nearby electric field, phase field, and stress field during the crack development process inside the post insulator, observe and simulate the crack development throughout the evolution process, and compare and verify the simulation results with the time engineering failure. Figure 3 , Attachment Figure 4 shown.

[0090] The phase field model is considered to simulate the discharge brittle cracking of post insulators under the coupling of electrical stress and mechanical stress, which can more effectively and accurately characterize and predict the evolution state and development mechanism of discharge brittle cracking.

[0091] In this embodiment, in step S1, material parameters used for simulation calculation of epoxy resin-alumina composite material are set in COMSOL finite element software, and the material parameters include: density, Young's modulus, Poisson's ratio, relative dielectric constant, and critical energy release rate.

[0092] In this embodiment, the stress tensile method is used in step S1 to detect the epoxy casting sample model to obtain material parameters, and the density is 1200kg / m 3 , Young's modulus is 3 GPa, Poisson's ratio is 0.3, relative dielectric constant is 3.5, and critical energy release rate is 3800 J / m 2 .

[0093] In this embodiment, in step S2, a geometric model of a GIL post insulator is constructed in COMSOL finite element software, including a high-voltage electrode, an epoxy resin-alumina casting part, and a ground electrode. An air gap and an initial crack are set on the left side of the post insulator, and the geometric model of the post insulator is meshed. The post insulator is composed of: high-voltage electrode, air gap, initial crack, and ground electrode from top to bottom.

[0094] In this embodiment, step S3 includes the following steps:

[0095] S31. Using Maxwell's equations, we can solve the electric field related expressions as follows:

[0096]

[0097] in is the Hamiltonian operator, H is the magnetic induction intensity vector, J is the current density vector, D is the electric displacement vector, E is the electric field intensity vector, B is the magnetic flux density vector, ρ is the charge density, × is the curl operation, · is the divergence operation, is the symbol of partial derivative function, t is time;

[0098] S32. Establish the derivation formula as follows:

[0099]

[0100] Where σ is the conductivity, j is the imaginary operator, ω is the angular frequency, ε is the dielectric constant of the material, is the scalar potential;

[0101] S33. The initial conditions are set as: the high voltage electrode is 500kV and the ground electrode is 0kV.

[0102] In this embodiment, step S4 includes the following steps:

[0103] S41. The expression for elastic strain energy of stress field is as follows:

[0104] ψ b =∫ Ω g(φ)ψ + (ε)+ψ - (ε)dΩ

[0105]

[0106] <ε1+ε2+ε3> + =1 / 2((ε1+ε2+ε3)+|ε1+ε2+ε3|)

[0107] <ε1+ε2+ε3> - =1 / 2((ε1+ε2+ε3)-|ε1+ε2+ε3|)

[0108]

[0109]

[0110] Where Ω is the infinitesimal region of the three-pillar insulator volume integral, g(φ) is the free energy function, ψ + (ε) is the free energy density tensile stress, ψ - (ε) is the free energy density compressive stress, λ and μ are both Lame constants, ε1 is the anisotropic strain in the x direction, ε2 is the anisotropic strain in the y direction, ε3 is the anisotropic strain in the z direction, and |·| is the absolute value. Since stretching will cause the insulator crack to extend, this decomposition only uses the strain energy in the tensile condition as the driving force for crack extension.

[0111] In this embodiment, step S5 includes the following steps:

[0112] S51. The evolution of the conservative variables at any point i in a phase field simulation over time is defined by the Cahn-Hilliard equation as follows:

[0113]

[0114] Where c i is the i-th conservative variable, M i is the i-th conservative variable ci is the kinetic mobility of the system, and F is the total free energy functional of the system.

[0115] S52. The evolution of the conservative variables at any point j in the phase field simulation with time is defined by the Allen-Cahn equation as follows:

[0116] Where η j is the jth microstructure unit, L j is the jth microstructure unit η j Kinetic mobility of the energy factors contained.

[0117] S53. In essence, the above two equations are expressions of the minimization of the free energy of the three-pillar insulator in a stable state. When the boundary conditions are fixed, for non-conservative variables, the total free energy functional F of the system is derived with respect to time as follows:

[0118]

[0119] Where η is a tiny structural unit, and L is the kinetic mobility of the energy factor contained in the tiny structural unit η. S54. Under fixed boundary conditions, for conservative variables, the total free energy functional F of the system is derived with respect to time as follows:

[0120]

[0121] Where J is the flux vector, J c is the flux vector under conservative variables, M is the kinetic mobility, c is the order variable, For the flux vector under the i-th conservative variable, the equation is established as follows:

[0122] In the formula is the surface integral of the conservative variables, the flux at the boundary is zero, and the equation is:

[0123]

[0124] S55. The dynamics of the phase field model evolution is to minimize the thermodynamic free energy of the material. Starting from a uniform free energy density, Taylor expansion is performed using component derivatives. For the isotropic material used in three-post insulators, the free energy is as follows:

[0125] Where f is the free energy, f0(c) is the initial free energy, κ i is the coefficient of the i-th Taylor expansion term, i∈{1,...,n}, and n is the total number of Taylor expansion terms.

[0126] S56. The Cahn-Hilliard free energy functional is established as follows:

[0127]

[0128] Where V is the volume integral, the first term of the integrand is the local chemical free energy density, and χ is the gradient energy coefficient; the free energy functional is established as follows:

[0129]

[0130] Where f local (c i ,η j ) is the local chemical free energy density, is the gradient energy density, f app (c i ,η i ) is the additional energy term,

[0131] γ i is the i-th multidimensional gradient energy evolution coefficient among N conservative field variables, γ j is the j-th multidimensional gradient energy evolution coefficient among the M non-conservative field variables.

[0132] In this embodiment, the calculation time step in step S6 is set to 0.2 μs, and the upper limit of the simulation time is set to 200 μs.

[0133] Example 2

[0134] A phase field simulation device for discharge brittle fracture fault of ultra-high voltage GIS / GIL post insulator, comprising: a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other through the communication bus; wherein:

[0135] The memory is used to store computer programs;

[0136] The processor is configured to execute, by running a program stored in the memory:

[0137] Set material parameters in COMSOL finite element software.

[0138] The geometric model of GIL post insulator is built in COMSOL finite element software.

[0139] The electric field model was established in COMSOL finite element software.

[0140] The stress field model was established in COMSOL finite element software.

[0141] The phase field model was established in COMSOL finite element software.

[0142] The calculation time step and the upper limit of the simulation time are set, and each model is iteratively solved in the geometric model area of ​​the post insulator to observe the crack development process until breakdown or the upper limit of the simulation time is reached.

[0143] The nearby electric field, phase field, and stress field during the crack development process inside the post insulator are obtained, the crack development is observed and simulated throughout the evolution process, and the simulation results are compared and verified with time engineering failures.

[0144] Example 3

[0145] A computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the computer program implements:

[0146] Set material parameters in COMSOL finite element software.

[0147] The geometric model of GIL post insulator is built in COMSOL finite element software.

[0148] The electric field model was established in COMSOL finite element software.

[0149] The stress field model was established in COMSOL finite element software.

[0150] The phase field model was established in COMSOL finite element software.

[0151] The calculation time step and the upper limit of the simulation time are set, and each model is iteratively solved in the geometric model area of ​​the post insulator to observe the crack development process until breakdown or the upper limit of the simulation time is reached.

[0152] The nearby electric field, phase field, and stress field during the crack development process inside the post insulator are obtained, the crack development is observed and simulated throughout the evolution process, and the simulation results are compared and verified with time engineering failures.

[0153] It should also be understood that in the embodiments of this document, the term "and / or" is only a description of the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects before and after are in an "or" relationship.

[0154] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this article.

[0155] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0156] In the several embodiments provided herein, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of the units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, or can be electrical, mechanical or other forms of connection.

[0157] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of this article.

[0158] In addition, each functional unit in each embodiment of this invention can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit. If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of this invention is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of this invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a disk or an optical disk.

[0159] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A phase field simulation method for discharge brittle fracture fault of ultra-high voltage GIS / GIL post insulator, characterized in that: include: S1. Set material parameters in COMSOL finite element software; S2. Build the geometric model of GIL post insulator in COMSOL finite element software; S3. Establish an electric field model in COMSOL finite element software; S4. Establish a stress field model in COMSOL finite element software; S5. Establish a phase field model in COMSOL finite element software; S6. Set the calculation time step and the upper limit of the simulation time, iteratively solve the models in steps S3 to S5 in the region of the post insulator geometric model, and observe the crack development process until the breakdown or the simulation time upper limit is reached; S7. Obtain the nearby electric field, phase field, and stress field during the crack development process inside the post insulator, observe and simulate the crack development throughout the evolution process, and compare and verify the simulation results with the time engineering failure.

2. The phase field simulation method for discharge brittle fracture fault of ultra-high voltage GIS / GIL post insulator according to claim 1 is characterized by: In step S1, material parameters used for simulation calculation of epoxy resin-alumina composite material are set in COMSOL finite element software, and the material parameters include: density, Young's modulus, Poisson's ratio, relative dielectric constant, and critical energy release rate.

3. The phase field simulation method for discharge brittle fracture fault of ultra-high voltage GIS / GIL post insulator according to claim 2 is characterized by: In step S1, the stress tensile method is used to detect the epoxy casting sample model to obtain material parameters, and the density is 1200kg / m 3 , Young's modulus is 3 GPa, Poisson's ratio is 0.3, relative dielectric constant is 3.5, critical energy release rate is 3800 J / m 2 .

4. The phase field simulation method for discharge brittle fracture fault of ultra-high voltage GIS / GIL post insulator according to claim 1 is characterized in that: In step S2, a geometric model of a GIL post insulator is constructed in COMSOL finite element software, including a high-voltage electrode, an epoxy-alumina casting part, and a ground electrode. An air gap and an initial crack are set on the left side of the post insulator, and the geometric model of the post insulator is meshed. The post insulator is composed of: a high-voltage electrode, an air gap, an initial crack, and a ground electrode from top to bottom.

5. The phase field simulation method for discharge brittle fracture fault of ultra-high voltage GIS / GIL post insulator according to claim 1 is characterized in that: Step S3 includes the following steps: S31. Using Maxwell's equations, we can solve the electric field related expressions as follows: Where ▽ is the Hamiltonian operator, H is the magnetic induction intensity vector, J is the current density vector, D is the electric displacement vector, E is the electric field intensity vector, B is the magnetic flux density vector, ρ is the charge density, × is the curl operation, · is the divergence operation, is the symbol of partial derivative function, t is time; S32. Establish the derivation formula as follows: Where σ is the conductivity, j is the imaginary operator, ω is the angular frequency, ε is the dielectric constant of the material, is the scalar potential; S33. The initial conditions are set as: the high voltage electrode is 500kV and the ground electrode is 0kV.

6. The phase field simulation method for discharge brittle fracture fault of ultra-high voltage GIS / GIL post insulator according to claim 1 is characterized in that: Step S4 includes the following steps: S41. The expression for elastic strain energy of stress field is as follows: Where Ω is the infinitesimal region of the three-pillar insulator volume integral, g(φ) is the free energy function, ψ + (ε) is the free energy density tensile stress, ψ - (ε) is the free energy density compressive stress, λ and μ are both Lame constants, ε1 is the anisotropic strain in the x direction, ε2 is the anisotropic strain in the y direction, ε3 is the anisotropic strain in the z direction, and |·| is the absolute value.

7. The phase field simulation method for discharge brittle fracture fault of ultra-high voltage GIS / GIL post insulator according to claim 1 is characterized in that: Step S5 includes the following steps: S51. The evolution of the conservative variables at any point i in a phase field simulation over time is defined by the Cahn-Hilliard equation as follows: Where c i is the i-th conservative variable, M i is the i-th conservative variable c i The kinetic mobility of the system, F is the total free energy functional of the system; S52. The evolution of the conservative variables at any point j in the phase field simulation with time is defined by the Allen-Cahn equation as follows: Where η j is the jth microstructure unit, L j is the jth microstructure unit η j The kinetic mobility of the energy factors involved; S53. When the boundary conditions are fixed, for non-conservative variables, the time derivative of the total free energy functional F of the system is as follows: In the formula, η is a tiny structural unit, and L is the kinetic mobility of the energy factor contained in the tiny structural unit η; S54. When the boundary conditions are fixed, for conservative variables, the time derivative of the total free energy functional F of the system is as follows: Where J is the flux vector, J c is the flux vector under conservative variables, M is the kinetic mobility, c is the order variable, For the flux vector under the i-th conservative variable, the equation is established as follows: In the formula is the surface integral of the conservative variables, the flux at the boundary is zero, and the equation is: S55. Starting from the uniform free energy density, Taylor expansion is performed using component derivatives. For the isotropic material used in three-post insulators, the free energy is as follows: Where f is the free energy, f0(c) is the initial free energy, κ i is the coefficient of the i-th Taylor expansion term, i∈{1,...,n}, and n is the total number of Taylor expansion terms; S56. The Cahn-Hilliard free energy functional is established as follows: Where V is the volume integral, χ is the gradient energy coefficient; The free energy functional is established as follows: Where f local (c i ,η j ) is the local chemical free energy density, f grad (▽c i ,▽η j ) is the gradient energy density, f app (c i ,η i ) is the additional energy term, γ i is the i-th multidimensional gradient energy evolution coefficient among N conservative field variables, γ j is the j-th multidimensional gradient energy evolution coefficient among the M non-conservative field variables.

8. The phase field simulation method for discharge brittle fracture fault of ultra-high voltage GIS / GIL post insulator according to claim 1 is characterized by: In step S6, the calculation time step is set to 0.2 μs, and the upper limit of the simulation time is set to 200 μs.

9. A phase field simulation device for discharge brittle fracture fault of ultra-high voltage GIS / GIL post insulator, characterized in that: include: A processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus; wherein: The memory is used to store computer programs; The processor is configured to execute, by running a program stored in the memory: Set material parameters in COMSOL finite element software; Build the geometric model of GIL post insulator in COMSOL finite element software; Establish an electric field model in COMSOL finite element software; Establish a stress field model in COMSOL finite element software; Establish a phase field model in COMSOL finite element software; Set the calculation time step and simulation time limit, iteratively solve each model in the geometric model area of ​​the post insulator, and observe the crack development process until breakdown or reaching the simulation time limit; The nearby electric field, phase field, and stress field during the crack development process inside the post insulator are obtained, the crack development is observed and simulated throughout the evolution process, and the simulation results are compared and verified with time engineering failures.

10. A computer-readable storage medium, characterized in that: The computer readable storage medium stores a computer program, which, when executed by a processor, implements: Set material parameters in COMSOL finite element software; Build the geometric model of GIL post insulator in COMSOL finite element software; Establish an electric field model in COMSOL finite element software; Establish a stress field model in COMSOL finite element software; Establish a phase field model in COMSOL finite element software; Set the calculation time step and simulation time limit, iteratively solve each model in the geometric model area of ​​the post insulator, and observe the crack development process until breakdown or reaching the simulation time limit; The nearby electric field, phase field, and stress field during the crack development process inside the post insulator are obtained, the crack development is observed and simulated throughout the evolution process, and the simulation results are compared and verified with time engineering failures.

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