Method for evaluating ablation cracking degree of environment-friendly gas high-voltage circuit breaker contact material

Abstract

The embodiment of the invention discloses a method for evaluating the ablation cracking degree of an environment-friendly gas high-voltage circuit breaker contact material. The method comprises the steps that thermal parameters and mechanical parameters of the high-voltage circuit breaker contact material are collected; establishing a three-dimensional geometric model of the high-voltage circuit breaker contact according to the thermal parameters and the mechanical parameters; analyzing the high-voltage circuit breaker contact according to an extended finite element method, and obtaining simulation results of temperature and stress distribution of the high-voltage circuit breaker contact in the working process; according to the simulation result, the ablation degree and the cracking degree of the high-voltage circuit breaker contact material are determined, and a corresponding evaluation result is obtained. Through accurate three-dimensional modeling, data processing and evaluation result obtaining, evaluation and optimization of the high-voltage circuit breaker contact material are facilitated, and a reference is provided for design and application of the high-voltage circuit breaker contact material under the large-current open-end condition.

Description

Technical Field

[0001] The invention relates to the technical field of material detection, and in particular to a method for evaluating the degree of ablation and cracking of contact materials of an environmentally friendly gas high-voltage circuit breaker. Background Art

[0002] As an important equipment in the power system, the performance and reliability of high-voltage circuit breakers are directly related to the safe and stable operation of the power grid. As a key component of high-voltage circuit breakers, contacts will generate high temperatures due to arc discharge when breaking large currents, causing contact material ablation. The temperature rise on the contact surface may also produce corresponding thermal stress. When the continuous thermal stress exceeds the tensile strength of the material, the contact material may crack, which will cause the conductivity and mechanical strength of the contact to decrease, thereby affecting the working state and service performance of the high-voltage circuit breaker. At present, environmentally friendly gas arc extinguishing high-voltage circuit breakers are a hot spot in research and development. Compared with SF6 gas, the arc breaking state of mixed gases such as C4F7N is more complicated, and the ablation effect on the contacts when used for arc extinguishing is more complicated. The relevant situation is not yet clear.

[0003] With the development of power systems, higher requirements are placed on high-voltage circuit breakers, including higher voltage levels, larger capacities, more compact structures, and the use of new environmentally friendly gases. These requirements make the design and evaluation methods of contact materials more important in the design and application of high-voltage circuit breakers.

[0004] Traditional contact material evaluation methods are often based on experimental tests and empirical judgments, which make it difficult to accurately predict the ablation and cracking characteristics of contacts under high current breaking conditions. Therefore, it is particularly important to study a more accurate and efficient method for evaluating the ablation and cracking degree of high-voltage circuit breaker contact materials. Summary of the invention

[0005] Based on this, it is necessary to propose a method for evaluating the degree of ablation and cracking of contact materials of environmentally friendly gas high-voltage circuit breakers to address the above problems.

[0006] A method for evaluating the degree of ablation and cracking of contact materials of an environmentally friendly gas high-voltage circuit breaker, the method comprising:

[0007] Collect thermal parameters and mechanical parameters of high-voltage circuit breaker contact materials;

[0008] Establishing a three-dimensional geometric model of a high-voltage circuit breaker contact according to the thermal parameters and mechanical parameters;

[0009] Analyzing the high-voltage circuit breaker contact according to the extended finite element method to obtain simulation results of temperature and stress distribution of the high-voltage circuit breaker contact during operation;

[0010] According to the simulation results, the degree of ablation and cracking of the high-voltage circuit breaker contact material is determined to obtain corresponding evaluation results.

[0011] In the above scheme, the thermal parameters and mechanical parameters of the high-voltage circuit breaker contact material are collected, specifically including:

[0012] The mechanical parameters include the density, elastic modulus, and Poisson's ratio of the high-voltage circuit breaker material; the thermal parameters include the thermal expansion coefficient, thermal conductivity, specific heat capacity, and yield strength of the high-voltage circuit breaker material.

[0013] In the above scheme, the three-dimensional geometric model includes an upper insulating column, a contact arc, a cathode contact, an anode contact, a lower insulating column, a large current generator, a cathode connecting cable, an anode cable, a current coil, a voltage probe, a lens, a slit, a spectrometer, a data processing analyzer and a simulation simulator;

[0014] The cathode contact and the anode contact are respectively fixed between the upper insulating column and the lower insulating column, and are placed in horizontal alignment; the cathode contact and the anode contact ports are respectively connected to the output port of the high current generator through the cathode cable and the anode cable; the breakdown discharge between the cathode contact and the anode contact generates a contact arc; the current coil and the voltage probe are connected to the anode cable to measure the loop current and voltage waveforms respectively; the lens is assembled on the spectrometer through a slit to detect the plasma characteristics and parameters in the contact arc; the data processing analyzer performs calculations and comparisons based on the simulation simulator.

[0015] In the above scheme, the plasma parameters and heat load parameters are obtained according to the spectrometer in the three-dimensional geometric model, specifically including:

[0016] The contact arc is tested by a spectrometer to obtain the central wavelength and Stark broadening of the spectral line, and the electron density data N is calculated based on the relationship between the Stark broadening and the electron density. e ;

[0017] Based on the plasma radiation transport equation, combined with the LTE hypothesis and related equations, the plasma radiation spectrum line shape is numerically fitted to obtain the plasma temperature parameter T e ;

[0018] Based on the plasma parameters, a parallel heat load parameter q″ is determined.

[0019] In the above scheme, the analysis of the high-voltage circuit breaker contact according to the extended finite element method to obtain the simulation results of the temperature and stress distribution of the high-voltage circuit breaker contact during operation specifically includes:

[0020] The maximum temperature T of the surface of the high-voltage circuit breaker contact material is calculated according to the heat conduction equationmax ;

[0021] Based on the mechanical equilibrium equation and Hooke's law, the stress σ and strain ε in the high-voltage circuit breaker contact material are determined.

[0022] In the above scheme, the maximum temperature T of the surface of the high-voltage circuit breaker contact material is calculated according to the heat conduction equation. max , including:

[0023] The temperature distribution of the high-voltage circuit breaker contact material is determined by the heat conduction equation:

[0024]

[0025] The boundary conditions of the high-voltage circuit breaker contact material are preset as follows:

[0026]

[0027] The initial conditions of the high-voltage circuit breaker contact material are preset as follows:

[0028] T(z,0)=T0

[0029] Under constant heat load conditions, the maximum temperature on the surface of the high-voltage circuit breaker contact material is determined by the following formula:

[0030]

[0031] Where T is temperature, z is axial direction, t is time, C p is the specific heat capacity, ρ is the density, λ is the thermal conductivity, W is the heating power density, and T0 is the initial temperature.

[0032] In the above scheme, the stress σ and strain ε in the high-voltage circuit breaker contact material are determined based on the mechanical equilibrium equation and Hooke's law, specifically including:

[0033] When the high-voltage circuit breaker contact material is subjected to external effects and undergoes a slight deformation, its micro-element is decomposed to be subjected to normal stress σ and tangential shear stress τ, respectively, and generates corresponding normal strain ε and shear strain γ:

[0034] σ=Eε

[0035] τ=Gγ

[0036] Among them, E is the elastic modulus, G is the shear modulus, σ is the normal stress, τ is the shear stress, ε is the normal strain, and γ is the shear strain.

[0037] In the above scheme, the stress σ and strain ε in the high-voltage circuit breaker contact material are determined based on the mechanical equilibrium equation and Hooke's law, specifically including:

[0038] Based on the mechanical equilibrium equation and Hooke's law, the stress is expressed as:

[0039] σ zz =σ xy =σ xz =σ yz =0

[0040]

[0041] u(T,T0)=α(T-T0)

[0042] Among them, σ is stress, E is elastic modulus, ν is Poisson's ratio, u is elongation, and α is thermal expansion coefficient.

[0043] The surface elastic deformation ε e It is expressed as:

[0044]

[0045] Plastic deformation is determined according to the Hollomon equation:

[0046]

[0047] Among them, K is the strength coefficient, ε is the deformation, σ 02 is the yield limit of 0.2% plastic deformation, and n is the strain-hardening exponent.

[0048] In the above scheme, determining the degree of ablation and cracking of the high-voltage circuit breaker contact material according to the simulation results and obtaining the corresponding evaluation results specifically includes:

[0049] The crack penetration function H(x) and the asymptotic function F that captures the singular points around the crack tip are used. α (x) indicates the initiation and expansion of cracks in the contact material of the high-voltage circuit breaker:

[0050]

[0051] Among them, N i (x) is the linear function of the node displacement, x is the Gaussian integration point, x * is the point closest to the crack, and n is the outer x of the crack. * The perpendicular vector at i is the additional degree of freedom of the element node penetrated by the crack tip, b i α is the degree of freedom vector of the enriched node, r and θ are the polar coordinates of the local coordinate system defined by the crack tip, and u(x) is the displacement function.

[0052] In the above scheme, determining the degree of ablation and cracking of the high-voltage circuit breaker contact material according to the simulation results and obtaining the corresponding evaluation results specifically includes:

[0053] According to the critical crack size L c Determine the critical energy release rate G c :

[0054]

[0055] Where wf is the fracture energy, σ f is the changing fracture stress, G is the energy release rate, G c is the critical energy release rate;

[0056] The ablation degree and cracking degree of the corresponding high-voltage circuit breaker contact material are determined according to the critical energy release rate.

[0057] The use of the embodiments of the present invention has the following beneficial effects: first collect the thermal parameters and mechanical parameters of the high-voltage circuit breaker contact material; establish a three-dimensional geometric model of the high-voltage circuit breaker contact based on the thermal parameters and mechanical parameters; analyze the high-voltage circuit breaker contact according to the extended finite element method to obtain the simulation results of the temperature and stress distribution of the high-voltage circuit breaker contact during operation; determine the degree of ablation and cracking of the high-voltage circuit breaker contact material based on the simulation results, and obtain the corresponding evaluation results. The present invention uses accurate three-dimensional modeling, data processing, and acquisition of evaluation results, which is conducive to the evaluation and optimization of high-voltage circuit breaker contact materials, and provides a reference for the design and application of high-voltage circuit breaker contact materials under high current starting conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0059] in:

[0060] Figure 1 A schematic flow chart of a method for evaluating the degree of ablation and cracking of contact materials of an environmentally friendly gas high-voltage circuit breaker in one embodiment;

[0061] Figure 2 It is a structural schematic diagram of the three-dimensional geometric model. DETAILED DESCRIPTION

[0062] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0063] In the following description, a large number of specific details are given in order to provide a more thorough understanding of the present invention; however, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details; in other examples, in order to avoid confusion with the present invention, some technical features known in the art are not described, and it should be understood that the present invention can be implemented in different forms and should not be interpreted as limited to the embodiments presented here; on the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art.

[0064] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "a", "an" and "said / the" are also intended to include the plural forms, unless the context clearly indicates otherwise, and it should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0065] The present invention proposes a method for evaluating the degree of ablation and cracking of high-voltage circuit breaker contact materials based on extended finite element thermo-mechanical analysis. The method builds a contact ablation simulation and plasma characteristic diagnosis experimental platform, uses a spectrometer to diagnose and detect the spectral line information of the arc plasma between the contacts of the high-voltage circuit breaker, and then calculates the plasma electron density and temperature characteristic parameters. Based on these plasma parameters, the surface deposition heat load of the contact material can be further calculated, and then the extended finite element thermo-mechanical analysis method is used to evaluate the degree of ablation and cracking of the high-voltage circuit breaker contacts. This method provides a more accurate and reliable reference basis for the design and application of high-voltage circuit breaker contact materials under large current starting conditions.

[0066] To facilitate understanding, the relevant terms involved in this application are first introduced below.

[0067] (1) High-voltage circuit breaker contact materials refer to materials used in high-voltage circuit breakers as key components for circuit conduction and disconnection. During the operation of high-voltage circuit breakers, such materials need to withstand extreme conditions such as high current, high voltage and arc erosion. Therefore, they are required to have good electrical conductivity, high thermal conductivity, high melting point, high strength, and excellent anti-ablation and anti-cracking properties. Common contact materials include copper, silver, tungsten, copper-tungsten alloy, etc., which need to be selected according to the specific use environment and requirements;

[0068] (2) Mechanical equilibrium equations, which are used in this application to analyze the deformation and stress distribution of high-voltage circuit breaker contact materials under force;

[0069] (3) Hooke's law describes the relationship between stress and strain in a solid material within the range of elastic deformation. Within the elastic limit, the deformation of an object is proportional to the external force that causes the deformation. This law is very useful in analyzing the elastic deformation and stress state of high-voltage circuit breaker contact materials under thermal load.

[0070] In order to thoroughly understand the present invention, a detailed structure will be presented in the following description to illustrate the technical solution proposed by the present invention; optional embodiments of the present invention are described in detail as follows, but in addition to these detailed descriptions, the present invention may also have other implementation methods.

[0071] like Figure 1 As shown, in one embodiment, a method for evaluating the degree of ablation and cracking of a contact material of an environmentally friendly gas high-voltage circuit breaker is provided. The method for evaluating the degree of ablation and cracking of a contact material of an environmentally friendly gas high-voltage circuit breaker includes steps S101 to S104, which are described in detail as follows:

[0072] S101, collecting thermal parameters and mechanical parameters of high-voltage circuit breaker contact materials;

[0073] First, the thermal and mechanical parameters of the high-voltage circuit breaker contact material are collected to ensure the comprehensiveness and accuracy of the evaluation basis, because the degree of ablation and cracking of the contact material is not only related to the thermal load, but also affected by the mechanical properties of the material itself.

[0074] In some embodiments, the thermal parameters and mechanical parameters of the high-voltage circuit breaker contact material are collected, specifically including:

[0075] The mechanical parameters include the density, elastic modulus and Poisson's ratio of the high-voltage circuit breaker material; the thermal parameters include the thermal expansion coefficient, thermal conductivity, specific heat capacity and yield strength of the high-voltage circuit breaker material.

[0076] S102, establishing a three-dimensional geometric model of a high-voltage circuit breaker contact according to thermal parameters and mechanical parameters;

[0077] Specifically, a three-dimensional geometric model of the high-voltage circuit breaker contact is established based on the collected thermal and mechanical parameters. The three-dimensional modeling can more realistically reflect the shape and force conditions of the contact in actual work, thereby improving the accuracy of the evaluation.

[0078] In some embodiments, the three-dimensional geometric model includes an upper insulating column, a contact arc, a cathode contact, an anode contact, a lower insulating column, a large current generator, a cathode connecting cable, an anode cable, a current coil, a voltage probe, a lens, a slit, a spectrometer, a data processing analyzer, and a simulation simulator;

[0079] The cathode contact and the anode contact are respectively fixed between the upper insulating column and the lower insulating column and placed in horizontal alignment; the cathode contact and the anode contact ports are respectively connected to the output port of the high current generator through the cathode cable and the anode cable; the cathode contact and the anode contact are subjected to breakdown discharge to generate a contact arc; the current coil and the voltage probe are connected to the anode cable to measure the loop current and voltage waveforms respectively; the lens is assembled on the spectrometer through a slit to detect the plasma characteristics and parameters in the contact arc; the data processing analyzer performs calculations and comparisons based on the simulation simulator.

[0080] Specifically, Figure 2 The figure shows a schematic diagram of the model, which includes an upper insulating column (1), a contact arc (2), a cathode contact (3), an anode contact (4), a lower insulating column (5), a high current generator (6), a cathode connecting cable (7), an anode cable (8), a current coil (9), a voltage probe (10), a lens (11), a slit (12), a spectrometer (13), a data processing analyzer (14), and a simulation algorithm (15).

[0081] The cathode contact (3) and the anode contact (4) are respectively fixed between the upper insulating column (1) and the lower insulating column (5), and the cathode contact (3) and the anode contact (4) are placed horizontally and aligned with a spacing of 10 mm; the cathode contact (3) and the anode contact (4) ports are respectively connected to the output port of the large current generator (6) through the cathode cable (7) and the anode cable (8); the cathode contact (3) and the anode contact (4) are broken down and discharged to generate a contact arc (2); the current coil (9) and the voltage probe (10) are connected to the anode cable (8) to measure the loop current and voltage waveforms respectively; the lens (11) is assembled in the spectrometer (13) through the slit (12) to detect the plasma characteristics and parameters in the contact arc (2); the data of the spectrometer (13) is imported into the data processing analyzer (14) for further analysis and statistics; the data processing analyzer (14) also performs calculation comparison on the simulation model based on the simulation algorithm (15).

[0082] In some embodiments, the plasma parameters and heat load parameters are obtained according to the spectrometer in the three-dimensional geometric model, specifically including:

[0083] The contact arc is tested using a spectrometer to obtain the central wavelength and Stark broadening of the spectral line. The electron density data N is calculated based on the relationship between Stark broadening and electron density. e ;

[0084] Based on the plasma radiation transport equation, combined with the LTE hypothesis and related equations, the plasma radiation spectrum line shape is numerically fitted to obtain the plasma temperature parameter T e ;

[0085] Based on the plasma parameters, the parallel heat load parameter q″ is determined.

[0086] Specifically, the contact arc (2) is tested using a spectrometer (13) to obtain the central wavelength λ0 of the spectral line and the Stark broadening wL. The spectral line profile dominated by the Stark broadening is approximately a Lorentz distribution:

[0087]

[0088] The electron density data can be calculated. The Stark broadening of the spectral line is generally directly related to the electron density and is minimally affected by temperature. The calculation formula is as follows:

[0089]

[0090] Where ω is the electron collision parameter / s-1; α is the electrostatic ion broadening parameter; Ne is the electron density / cm-3; Te is the electron temperature / K, where ω and α are both constants; considering the collision broadening effects of electrons and ions at the same time, the first term on the right side of the equal sign represents the effect of fast-moving electrons, and the second term represents the effect of slow-moving heavy ions. For non-hydrogen-like atoms, Stark broadening is mainly affected by the electron effect, and the ion effect can be ignored. For hydrogen atoms, there is also a simplified formula for calculation:

[0091]

[0092] Among them, α 1 / 2 is the half-height and half-width of the normalized profile. For the commonly used hydrogen Balmer system H α With H β The values ​​are 0.015 and 0.087 respectively.

[0093] Preferably, based on the plasma radiation transport equation, combined with the LTE hypothesis and the relationship between related equations, the radiation spectrum line shape of the plasma can be numerically fitted, and then the temperature parameters of the plasma can be calculated. The radiation transport equation of the plasma can be simplified as follows:

[0094] L λ =B λ (1-e -τ(λ))(4)

[0095] Among them, L λ is the absolute intensity of the spectral line / W·m -2 ·nm -1 ·sr -1 , B λ is the Planck equation, and τ(λ) is the optical thickness. The optical thickness τ(λ) is related to the plasma size range, temperature, composition and density, and its calculation expression is as follows:

[0096]

[0097] Where d is the radial dimension of the plasma jet, Q i (T) is the partition function, N i (T) is the particle density, i is the particle component, λ ul is the wavelength of the spectral line, g u is the statistical weight, A ul is the transition probability, E u is the excitation energy, T is the plasma temperature, k B is the Boltzmann constant, h is the Planck constant, c0 is the speed of light in vacuum, and P(λ) is the spectral line shape.

[0098] In the experiment, the corresponding spectral data can be obtained and the Stark broadening w can be measured. L , substituting into formula (2) we can get the electron density N e . The particle density N i The relationship between the plasma temperature T can be obtained by connecting the Boltzmann equation (6) and the Saha equation (7). Finally, by combining equations (4) and (5), the plasma temperature can be calculated by spectral line fitting:

[0099]

[0100]

[0101] Preferably, the heat load is the energy passing through a unit area per unit time, causing a temperature change within a unit distance along the energy flow direction. Based on the plasma parameters obtained by analysis and processing, the parallel heat load parameters can be calculated:

[0102]

[0103] Where keff is thermal conductivity / W·m-2·K-2; Γ ion is the ion flux / m-2·s-1; v is the plasma velocity along the jet direction / m·s-1.

[0104] S103, analyzing the high-voltage circuit breaker contacts according to the extended finite element method to obtain simulation results of the temperature and stress distribution of the high-voltage circuit breaker contacts during operation;

[0105] The extended finite element method is used to analyze the high-voltage circuit breaker contacts, which can simulate the temperature and stress distribution of the contacts during operation. The extended finite element method has significant advantages in dealing with complex crack propagation, material nonlinearity and other problems, and can therefore more accurately predict the ablation and cracking of the contacts.

[0106] In some embodiments, the high-voltage circuit breaker contacts are analyzed according to the extended finite element method to obtain simulation results of the temperature and stress distribution of the high-voltage circuit breaker contacts during operation, specifically including:

[0107] Calculate the maximum temperature T of the high-voltage circuit breaker contact material surface based on the heat conduction equation max ;

[0108] Based on the mechanical equilibrium equation and Hooke's law, the stress σ and strain ε in the contact material of the high-voltage circuit breaker are determined.

[0109] In some embodiments, the maximum temperature T of the surface of the high-voltage circuit breaker contact material is calculated according to the heat conduction equation. max , including:

[0110] The temperature distribution of high-voltage circuit breaker contact material is determined by the heat conduction equation:

[0111]

[0112] The boundary conditions of the preset high-voltage circuit breaker contact material are:

[0113]

[0114] The initial conditions of the high-voltage circuit breaker contact material are preset as follows:

[0115] T(z,0)=T0 (11)

[0116] Under constant heat load conditions, the maximum temperature on the surface of the high-voltage circuit breaker contact material is determined by the following formula:

[0117]

[0118] Where T is temperature, z is axial direction, t is time, C p is the specific heat capacity, ρ is the density, λ is the thermal conductivity, W is the heating power density, and T0 is the initial temperature.

[0119] In some embodiments, based on the mechanical equilibrium equation and Hooke's law, the stress σ and strain ε in the high-voltage circuit breaker contact material are determined, specifically including:

[0120] When the high-voltage circuit breaker contact material is subjected to external forces and undergoes a slight deformation, its micro-element is decomposed into normal stress σ and tangential shear stress τ, and generates corresponding normal strain ε and shear strain γ:

[0121] σ=Eε(13)

[0122] τ=Gγ(14)

[0123] Among them, E is the elastic modulus, G is the shear modulus, σ is the normal stress, τ is the shear stress, ε is the normal strain, and γ is the shear strain.

[0124] Furthermore, there is a relationship between Young's modulus, shear modulus and Poisson's ratio v:

[0125]

[0126] For isotropic materials, the stress and strain in each direction of the microelement can be described by the generalized Hooke's law:

[0127]

[0128]

[0129] The fourth strength theory (maximum distortion energy density theory), namely the Von Mises strength, is used to analyze the fracture process, where the relationship between the Von Mises stress σ and the principal stress is:

[0130]

[0131] In some embodiments, based on the mechanical equilibrium equation and Hooke's law, the stress σ and strain ε in the high-voltage circuit breaker contact material are determined, specifically including:

[0132] Based on the mechanical equilibrium equation and Hooke's law, the stress is expressed as:

[0133] σ zz =σ xy =σ xz =σ yz =0(19)

[0134]

[0135] u(T,T0)=α(T-T0)(21)

[0136] Among them, σ is stress, E is elastic modulus, ν is Poisson's ratio, u is elongation, and α is thermal expansion coefficient.

[0137] The surface elastic deformation ε e It is expressed as:

[0138]

[0139] Plastic deformation is determined according to the Hollomon equation:

[0140]

[0141] Among them, K is the strength coefficient, ε is the deformation, σ 02 is the yield limit of 0.2% plastic deformation, and n is the strain-hardening exponent.

[0142] Due to boundary constraints and the homogeneity of the material, the displacement and extension along the surface are equal to zero:

[0143]

[0144] S104. Determine the degree of ablation and cracking of the high-voltage circuit breaker contact material according to the simulation results, and obtain corresponding evaluation results.

[0145] Based on the simulation results, the degree of ablation and cracking of the high-voltage circuit breaker contact material can be directly determined and the corresponding evaluation results can be obtained. This method is not only intuitive and easy to understand, but also has high reliability because it is based on scientific simulation and calculation.

[0146] In some embodiments, according to the simulation results, the degree of ablation and cracking of the high-voltage circuit breaker contact material is determined, and the corresponding evaluation results are obtained, specifically including:

[0147] The crack penetration function H(x) and the asymptotic function F that captures the singular points around the crack tip are used. α (x) indicates the initiation and expansion of cracks in the contact material of the high-voltage circuit breaker:

[0148]

[0149] Among them, N i (x) is the linear function of the node displacement, x is the Gaussian integration point, x * is the point closest to the crack, and n is the outer x of the crack. * The perpendicular vector at i is the additional degree of freedom of the element node penetrated by the crack tip, b i α is the degree of freedom vector of the enriched node, r and θ are the polar coordinates of the local coordinate system defined by the crack tip, and u(x) is the displacement function.

[0150] In some embodiments, according to the simulation results, the degree of ablation and cracking of the high-voltage circuit breaker contact material is determined, and the corresponding evaluation results are obtained, specifically including:

[0151] According to the critical crack size Lc Determine the critical energy release rate G c :

[0152]

[0153]

[0154] Where wf is the fracture energy, σ f is the changing fracture stress, G is the energy release rate, G c is the critical energy release rate;

[0155] The degree of ablation and cracking of the corresponding high-voltage circuit breaker contact material is determined according to the critical energy release rate.

[0156] Among them, there is a relationship between the critical energy release rate Gc and the critical crack size Lc:

[0157]

[0158] Among them, the stress σ f The energy release rate G represents the fracture driving force, while the critical energy release rate Gc represents the fracture properties of the material.

[0159] In summary, this evaluation method can not only evaluate the degree of ablation and cracking of existing contact materials, but also provide a scientific basis for the design and improvement of contact materials. By simulating the contact performance under different materials and structures, the contact design can be optimized and the overall performance and reliability of the circuit breaker can be improved.

[0160] The present application also discloses a readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the following steps:

[0161] Collect thermal parameters and mechanical parameters of high-voltage circuit breaker contact materials;

[0162] Establishing a three-dimensional geometric model of a high-voltage circuit breaker contact according to the thermal parameters and mechanical parameters;

[0163] Analyzing the high-voltage circuit breaker contact according to the extended finite element method to obtain simulation results of temperature and stress distribution of the high-voltage circuit breaker contact during operation;

[0164] According to the simulation results, the degree of ablation and cracking of the high-voltage circuit breaker contact material is determined to obtain corresponding evaluation results.

[0165] The present application also discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and the computer program is executed by the processor to perform the following steps:

[0166] Collect thermal parameters and mechanical parameters of high-voltage circuit breaker contact materials;

[0167] Establishing a three-dimensional geometric model of a high-voltage circuit breaker contact according to the thermal parameters and mechanical parameters;

[0168] Analyzing the high-voltage circuit breaker contact according to the extended finite element method to obtain simulation results of temperature and stress distribution of the high-voltage circuit breaker contact during operation;

[0169] According to the simulation results, the degree of ablation and cracking of the high-voltage circuit breaker contact material is determined to obtain corresponding evaluation results.

[0170] Those skilled in the art will understand that all or part of the processes in the above-mentioned embodiments can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in the present application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0171] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0172] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the present application. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. The above disclosure is only a preferred embodiment of the present invention, and of course it cannot be used to limit the scope of the rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope covered by the present invention.

Claims

1. A method for evaluating the degree of ablation and cracking of contact materials of an environmentally friendly gas high-voltage circuit breaker, characterized in that: The method comprises: Collect thermal and mechanical parameters of high-voltage circuit breaker contact materials; Establishing a three-dimensional geometric model of a high-voltage circuit breaker contact according to the thermal parameters and mechanical parameters; Analyzing the high-voltage circuit breaker contact according to the extended finite element method to obtain simulation results of temperature and stress distribution of the high-voltage circuit breaker contact during operation; According to the simulation results, the degree of ablation and cracking of the high-voltage circuit breaker contact material is determined, and the corresponding evaluation results are obtained.

2. The method for evaluating the degree of ablation and cracking of contact materials of an environmentally friendly gas high-voltage circuit breaker according to claim 1 is characterized in that: The acquisition of thermal parameters and mechanical parameters of high-voltage circuit breaker contact materials specifically includes: The mechanical parameters include the density, elastic modulus, and Poisson's ratio of the high-voltage circuit breaker material; the thermal parameters include the thermal expansion coefficient, thermal conductivity, specific heat capacity, and yield strength of the high-voltage circuit breaker material.

3. The method for evaluating the degree of ablation and cracking of contact materials of an environmentally friendly gas high-voltage circuit breaker according to claim 2 is characterized in that: The three-dimensional geometric model includes an upper insulating column, a contact arc, a cathode contact, an anode contact, a lower insulating column, a large current generator, a cathode connecting cable, an anode cable, a current coil, a voltage probe, a lens, a slit, a spectrometer, a data processing analyzer and a simulation simulator; The cathode contact and the anode contact are respectively fixed between the upper insulating column and the lower insulating column, and are placed in horizontal alignment; the cathode contact and the anode contact ports are respectively connected to the output port of the high current generator through the cathode cable and the anode cable; the breakdown discharge between the cathode contact and the anode contact generates a contact arc; the current coil and the voltage probe are connected to the anode cable to measure the loop current and voltage waveforms respectively; the lens is assembled on the spectrometer through a slit to detect the plasma characteristics and parameters in the contact arc; the data processing analyzer performs calculations and comparisons based on the simulation simulator.

4. The method for evaluating the degree of ablation and cracking of contact materials of an environmentally friendly gas high-voltage circuit breaker according to claim 3 is characterized in that: The plasma parameters and heat load parameters are obtained according to the spectrometer in the three-dimensional geometric model, including: The contact arc is tested by a spectrometer to obtain the central wavelength and Stark broadening of the spectral line, and the electron density data N is calculated based on the relationship between the Stark broadening and the electron density. e ; Based on the plasma radiation transport equation, combined with the LTE hypothesis and related equations, the plasma radiation spectrum line shape is numerically fitted to obtain the plasma temperature parameter T e ; Based on the plasma parameters, a parallel heat load parameter q″ is determined.

5. The method for evaluating the degree of ablation and cracking of contact materials of an environmentally friendly gas high-voltage circuit breaker according to claim 4 is characterized in that: The step of analyzing the high-voltage circuit breaker contact according to the extended finite element method to obtain simulation results of the temperature and stress distribution of the high-voltage circuit breaker contact during operation specifically includes: The maximum temperature T of the surface of the high-voltage circuit breaker contact material is calculated according to the heat conduction equation max ; Based on the mechanical equilibrium equation and Hooke's law, the stress σ and strain ε in the high-voltage circuit breaker contact material are determined.

6. The method for evaluating the degree of ablation and cracking of contact materials of an environmentally friendly gas high-voltage circuit breaker according to claim 5 is characterized in that: The maximum temperature T of the surface of the high-voltage circuit breaker contact material is calculated according to the heat conduction equation max , specifically including: The temperature distribution of the high-voltage circuit breaker contact material is determined by the heat conduction equation: The boundary conditions of the high-voltage circuit breaker contact material are preset as follows: The initial conditions of the high-voltage circuit breaker contact material are preset as follows: T(z,0)=T0 Under constant heat load conditions, the maximum temperature on the surface of the high-voltage circuit breaker contact material is determined by the following formula: Where T is temperature, z is axial direction, t is time, C p is the specific heat capacity, ρ is the density, λ is the thermal conductivity, W is the heating power density, and T0 is the initial temperature.

7. The method for evaluating the degree of ablation and cracking of contact materials of an environmentally friendly gas high-voltage circuit breaker according to claim 6 is characterized in that: The determining of the stress σ and strain ε in the high-voltage circuit breaker contact material based on the mechanical equilibrium equation and Hooke's law specifically includes: When the high-voltage circuit breaker contact material is subjected to external effects and undergoes a slight deformation, its micro-element is decomposed to be subjected to normal stress σ and tangential shear stress τ, respectively, and generates corresponding normal strain ε and shear strain γ: σ=Eε τ=Gγ Among them, E is the elastic modulus, G is the shear modulus, σ is the normal stress, τ is the shear stress, ε is the normal strain, and γ is the shear strain.

8. The method for evaluating the degree of ablation and cracking of contact materials of an environmentally friendly gas high-voltage circuit breaker according to claim 7 is characterized in that: The determining of the stress σ and strain ε in the high-voltage circuit breaker contact material based on the mechanical equilibrium equation and Hooke's law specifically includes: Based on the mechanical equilibrium equation and Hooke's law, the stress is expressed as: s zz =s xy =s xz =s yz =0 u(T,T0)=α(T-T0) Among them, σ is stress, E is elastic modulus, ν is Poisson's ratio, u is elongation, and α is thermal expansion coefficient. The surface elastic deformation ε e It is expressed as: Plastic deformation is determined according to the Hollomon equation: Among them, K is the strength coefficient, ε is the deformation, σ 02 is the yield limit of 0.2% plastic deformation, and n is the strain-hardening exponent.

9. The method for evaluating the degree of ablation and cracking of contact materials of an environmentally friendly gas high-voltage circuit breaker according to claim 8, characterized in that: Determining the degree of ablation and cracking of the high-voltage circuit breaker contact material according to the simulation results and obtaining corresponding evaluation results specifically includes: The crack penetration function H(x) and the asymptotic function F that captures the singular points around the crack tip are used. α (x) indicates the initiation and expansion of cracks in the contact material of the high-voltage circuit breaker: Among them, N i (x) is the linear function of the node displacement, x is the Gaussian integration point, x * is the point closest to the crack, and n is the outer x of the crack. * The perpendicular vector at i is the additional degree of freedom of the element node penetrated by the crack tip, b i α is the degree of freedom vector of the enriched node, r and θ are the polar coordinates of the local coordinate system defined by the crack tip, and u(x) is the displacement function.

10. The method for evaluating the degree of ablation and cracking of contact materials of an environmentally friendly gas high-voltage circuit breaker according to claim 9, characterized in that: Determining the degree of ablation and cracking of the high-voltage circuit breaker contact material according to the simulation results and obtaining corresponding evaluation results specifically includes: According to the critical crack size L c Determine the critical energy release rate G c : Where wf is the fracture energy, σ f is the changing fracture stress, G is the energy release rate, G c is the critical energy release rate; The ablation degree and cracking degree of the corresponding high-voltage circuit breaker contact material are determined according to the critical energy release rate.

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