CN115495944A - A method to obtain the electrical-thermal-stress distribution of switchgear under the influence of different factors - Google Patents

Abstract

The invention relates to a method for acquiring electric-thermal-stress distribution of a switch cabinet under the influence of different factors, which comprises the following steps: s1: establishing a three-dimensional physical model of a switch cabinet with multiple air chambers; s2: theoretical analysis of electromagnetic field, temperature conduction and solid mechanics of the switch cabinet; s3: adding electromagnetic-temperature-solid mechanics multi-physical field coupling; s4: setting corresponding parameters and boundary conditions; s5: carrying out mesh generation on the switch cabinet; s6: and (5) simulating to obtain the distribution of the electromagnetic field, the temperature field and the electric power of the switch cabinet. S7: and adding different fixed constraints to obtain different displacement amounts of the bus caused by stress. S8: the contact pressure at the joint was varied and the effect on temperature rise and stress was analyzed. The method of the invention is adopted to obtain the distribution characteristics of temperature rise, electric field intensity and electric power of the switch cabinet under different conditions. The method provides a basis for providing a theoretical basis for the optimized layout of the switch cabinet sensors, and the engineering design optimization and the heat dissipation structure design of the switch cabinet.

Description

A method to obtain the electrical-thermal-stress distribution of switchgear under the influence of different factors

technical field

The invention belongs to the field of electrical performance research of key equipment of a power transmission and distribution network, and relates to a method for obtaining the electric-thermal-stress distribution of a switchgear under the influence of different factors.

Background technique

As the key equipment of the power system, the power switchgear is widely used in the power transmission and distribution network, and is responsible for switching, controlling and protecting the electrical equipment. Its operation reliability directly affects the power supply quality and safety performance of the power system. In order to improve the operating reliability of the switchgear, reduce the risk of failure, and reduce the economic loss caused by failure, various monitoring equipment can be installed in the switchgear, and by analyzing and processing the monitoring data, the operating status detection and safety warning can be realized, so as to Ensure that O&M personnel find problems in a timely manner. In addition, under the background of smart grid construction, higher requirements are put forward for the real-time and accurate data obtained by switch cabinets.

However, when the switchgear is working, its eddy current loss and Joule heat will lead to temperature rise, and the Lorentz force generated by the electromagnetic will affect the non-fixed metal components. The above factors will affect the measurement of the characteristics of the switchgear by the sensor, seriously It may even affect its service life and affect the safe and stable operation of the equipment. Therefore, research on the temperature, electromagnetic distribution and electromotive force of the switchgear, determine the location of the highest temperature rise and the location of the largest electric field intensity, and analyze the influence of different factors on temperature and stress, will play a guiding role in optimizing the layout of various sensor locations , to help the development of the real-time monitoring system of the switchgear.

Contents of the invention

The purpose of the present invention is to provide a method for obtaining the electric-thermal-stress distribution of the switchgear under the influence of different factors, based on the actual structure and operating conditions of the switchgear, and using the finite element method to establish a coupling based on electromagnetic-temperature-solid mechanics The three-dimensional switchgear simulation model realizes the simulation method of the temperature, electric field intensity distribution and stress of the switchgear under the influence of different factors.

To achieve the above object, the present invention provides the following technical solutions, the steps of the method are as follows:

S1: Establish a simplified physical model of an electrical switchgear with multiple electrical rooms;

S2: Theoretical analysis of switchgear involving electromagnetic field, temperature conduction and solid mechanics;

S3: Add appropriate physical fields to conduct coupling analysis research of electromagnetic-heat transfer-solid mechanics;

S4: Set appropriate physical parameters and various boundary conditions based on the actual operating state of the switchgear;

S5: According to the geometric characteristics of each electrical room of the switchgear and the accuracy requirements of the calculation, mesh it, set the appropriate simulation time and step size, and set the solver according to the simulation requirements;

S6: The distribution results of the electromagnetic field and temperature field in the steady state of the switchgear under different environmental conditions are obtained by simulation, and post-processing is performed to obtain the distribution of temperature, electric field strength and Lorentz force. Determine the location of the hottest point, and compare and analyze the impact of different environmental conditions on the maximum temperature and the average temperature;

S7: Through the simulation, the change of the displacement of the busbar caused by the force due to the addition of different fixed constraints is obtained;

S8: Change the contact pressure at the connection through simulation, and analyze its influence on temperature rise and stress;

Further, step S1 is specifically to establish a three-dimensional physical model of a switchgear with multiple electrical rooms in the finite element software. An important feature of the internal structure of the model is valid and invalid, that is, sometimes some features need to be ignored according to the type of analysis problem . Focus on system heat sources and key components of the switchgear, while ignoring the fixing nuts and tiny electronic components that do not affect the analysis accuracy, rationally simplify the switchgear, reduce workload and improve efficiency.

Step S2 is specifically, the theoretical analysis of the electromagnetic field, temperature conduction and solid mechanics of the switchgear: calculate the eddy current loss according to the Maxwell electromagnetic theory of the switchgear operation, and bring the loss into the solid heat transfer as a heat source to calculate the temperature distribution; The Lorentz force is used to describe the electric force of the switchgear busbar.

(1) Electromagnetic field

When solving and analyzing the quasi-steady-state electromagnetic field problem, the magnetic field generated by the change of the electric field with time can be ignored, and only the electric field generated by the change of the magnetic field with time can be analyzed, thereby simplifying the electromagnetic problem. The macroscopic properties of the electromagnetic field are described by Maxwell's equations, and its differential form is as follows:

Where: D is the electric displacement; H is the magnetic field strength; B is the magnetic flux density; E is the electric field strength; ρ is the charge density; J is the current density.

ε represents the permittivity of coal in the magnetic field, in F/m; μ represents the magnetic permeability of coal in H/m; σ represents the electrical conductivity in S/m; for isotropic media, ε, Both μ and σ are scalar quantities.

(2) Solid heat transfer

Considering that the heat loss of the cabinet comes from eddy current loss, the heat is dissipated to the surrounding environment through natural convection heat transfer and heat radiation on the surface of the cabinet. The Joule loss of the busbar comes from the resistance heating loss and induction heating of the source current. The resistance of the busbar includes the current-carrying conductor resistance and contact resistance.

The Joule loss calculated by the eddy current field is imported as a heat source, and the corresponding radiation boundary conditions and convection heat dissipation boundary conditions are set to calculate the temperature field of the switchgear. The governing equation of the temperature field is:

为内热源强度。where ρ is the material density, λ and C are the thermal conductivity and specific heat of the material, respectively,

is the internal heat source intensity.

The outer surface of the busbar should satisfy the convection and radiation boundary conditions:

In the formula, q is the heat flux vector, T _a is the ambient temperature; k _e represents the convective heat transfer coefficient on the surface of the busbar; ε represents the heat generation rate on the surface of the busbar; σ represents the Stefan-Boltzmann constant.

(3) Solid Mechanics

The motion differential equation describing the motion of an object in a damped forced vibration system under the action of a disturbance force is:

分别表示整体坐标系下节点的位移、速度和加速度。In the formula, m is the total mass of the vibration system, C represents the viscous damping coefficient of the supporting vibration isolator when the object is moving, and K represents the force of the unit deformation of the spring stiffness. F ₀ sinωt represents the disturbance force received by the system, and the coordinate axis is placed on the static equilibrium position O of the object. x,

Respectively represent the displacement, velocity and acceleration of the node in the global coordinate system.

Step S3 specifically includes adding relevant physical fields and performing electromagnetic-temperature-solid mechanics multi-physics coupling. Based on the above theoretical analysis, the physical fields corresponding to each control equation are selected, that is, Maxwell’s equations correspond to the electromagnetic field, the convection, conduction and radiation of the temperature of the switchgear correspond to the physical field of solid heat transfer, and the stress of the equipment under the excitation of an external large current corresponds to the solid mechanics. physical field. Electromagnetic field and temperature field are coupled based on temperature and electromagnetic thermal effect; solid heat transfer and solid mechanics are coupled based on Lorentz force and thermal expansion effect, thereby realizing direct coupling of multiple physical fields;

Step S4 is specifically to set corresponding parameters and boundary conditions based on the actual operating state of the switchgear: parameters include electromagnetic, temperature and solid mechanics related parameters such as electrical conductivity, magnetic permeability, resistivity, and thermal conductivity of each part of the switchgear; boundary conditions include External stress and environmental constraints such as pressurization, grounding, current excitation, temperature boundary, and mechanical fixed constraints. Add the two-way coupling of temperature and material resistivity to improve the accuracy of simulation;

Step S5 is specifically, meshing the switch according to its geometric characteristics, and setting the simulation time and step size: setting the global mesh size, further refining the mesh according to the local geometric characteristics, and then constructing all the meshes , then set the simulation time and step size, and start the calculation until the time condition is met, and the simulation result converges;

Step S6 is specifically, firstly obtain the distribution results of the electromagnetic field, temperature field and time-average Lorentz force in the steady state of the switchgear through simulation, determine the location of the hottest point, and obtain the ambient temperature under the rated working condition as 293K, 298K, 303K, The average temperature rise and maximum temperature rise of the switchgear at 308K and 313K. The impact of different ambient temperatures on the maximum temperature and average temperature of the switchgear is compared and analyzed.

Step S7 is specifically to add different fixing constraints obtained through simulation, fix different parts, analyze the deformation caused by the force change of the busbar under different circumstances, and provide a reference for fixing the busbar of the switchgear. By fixing the circuit breaker, insulator, busbar end and other three parts, analyze the different changes of the busbar stress respectively;

Step S8 specifically is that the contact pressure of the corresponding connection inside the switchgear will affect its temperature rise and stress. By changing the contact pressure at the connection, and then changing the contact impedance, analyze its influence on the temperature rise and the corresponding the influence of force;

The beneficial effect of the present invention is that: adopting the method of the present invention can obtain the temperature distribution, electric field distribution characteristics and stress characteristics of the switchgear under the influence of different factors. The optimal arrangement of sensors provides a reliable theoretical basis.

Description of drawings

Fig. 1 is the electric-thermal-force simulation flowchart of switchgear of the present invention;

Fig. 2 is the overall three-dimensional physical model figure of switchgear of the present invention;

Fig. 3 is a map of the overall temperature field distribution and the highest point of temperature rise of the switchgear according to the embodiment of the present invention;

4 is a distribution diagram of the overall electric field intensity and current density of the switchgear according to the embodiment of the present invention;

Fig. 5 is a distribution diagram of the average Lorentz force in the X, Y, and Z directions of the switchgear according to the embodiment of the present invention;

Fig. 6 is a comparison curve of the average temperature and the maximum temperature of the switchgear under different ambient temperatures according to the embodiment of the present invention;

Fig. 7 is a distribution diagram of busbar displacement under different fixed constraints of the switchgear according to the embodiment of the present invention;

Fig. 8 is a distribution diagram of the temperature under different pressures at the junction of the switchgear according to the embodiment of the present invention;

Fig. 9 is a distribution diagram of the stress under different pressures at the connection of the switchgear according to the embodiment of the present invention;

detailed description:

The present invention will be described in detail below in conjunction with the accompanying drawings.

The present invention is a method for obtaining the electric-thermal-stress distribution of switchgear under the influence of different factors. The 3D simulation model of multi-physics field coupling, in which the eddy current loss of the electromagnetic field is used as the heat source of temperature conduction, the temperature distribution and the hottest temperature position of the switchgear are obtained based on the theoretical simulation of heat conduction, heat convection and heat radiation, and the metal in the electromagnetic field is also considered Influenced by the Lorentz force, the simulation of the electric power of the switchgear is realized. Specific steps are as follows:

1. Establish a 3D physical model of the switchgear

Draw the three-dimensional physical model of the switchgear in the finite element software, as shown in Figure 2, when performing coupling analysis, an important feature of the internal structure of the model is valid and invalid, that is, depending on the type of analysis problem, sometimes some features need to be analyzed neglect. Therefore, based on the following assumptions, a 10kV/3150A high-current switchgear is used as a prototype for three-dimensional modeling:

(1) Since the insulator only plays the role of insulating support, the shape characteristics of the insulator are simplified;

(2) Simplify the small components at the joints such as screws;

(3) The simplified circuit breaker is cylindrical;

2. Add physics field, set to add multi-physics field coupling

Add three physical fields of electromagnetic field, solid heat transfer, and structural mechanics, and perform coupled calculations:

(1) Electromagnetic field

When solving and analyzing the quasi-steady-state electromagnetic field problem, the magnetic field generated by the change of the electric field with time can be ignored, and only the electric field generated by the change of the magnetic field with time can be analyzed, thereby simplifying the electromagnetic problem. Through the differential form of Maxwell's equations, the differential equation for the finite element method to deal with electromagnetic field problems can be derived:

Where: D is the electric displacement; H is the magnetic field strength; B is the magnetic flux density; E is the electric field strength; ρ is the charge density; J is the current density.

In the formula: ε represents the dielectric constant of the magnetic field coal, in F/m; μ represents the magnetic permeability of the coal, in H/m; σ is the electrical conductivity, in S/m; for the isotropic medium , ε, μ, σ are all scalars.

(2) Solid heat transfer

Considering that the heat loss of the cabinet comes from eddy current loss, the heat is dissipated to the surrounding environment through natural convection heat transfer and heat radiation on the surface of the cabinet. The Joule loss of the busbar comes from the resistance heating loss and induction heating of the source current. The resistance of the busbar includes the current-carrying conductor resistance and contact resistance.

The Joule loss calculated by the eddy current field is imported as a heat source, and the corresponding radiation boundary conditions and convection heat dissipation boundary conditions are set to calculate the temperature field of the switchgear. The governing equation of the temperature field is:

为内热源强度。where ρ is the material density, λ and C are the thermal conductivity and specific heat of the material, respectively,

is the internal heat source intensity.

The conductivity of the material will change with the temperature. At 20°C, the resistivity of copper is 17.2 (mΩ·mm ² /m), and the temperature coefficient α of the selected resistivity is 0.004. The expression for the relationship between resistance and temperature is:

ρ(t)＝ρ ₀ (1+0.004(t-20)) ⑼

In the above formula, t is the current ambient temperature, and ρ0 is the resistivity of copper _at 20°C.

Based on the influence of the skin effect and proximity effect of the busbar, the resistance expression of the copper bar is summarized as follows:

In the formula, R is the resistance of the busbar, ρ0 is the copper resistivity _at 20 °C, L is the length of the busbar, S is the cross-sectional area of the busbar, _KJ is the skin effect coefficient, and _KL is the proximity effect coefficient.

This formula fully considers the influence of temperature on resistivity, and sets the two-way coupling relationship between temperature and resistivity, so that the resistivity changes continuously with temperature during the simulation process, making the results more accurate.

The outer surface of the busbar should satisfy the convection and radiation boundary conditions:

In the formula, q is the heat flux vector, T _a is the ambient temperature; k _e represents the convective heat transfer coefficient on the surface of the busbar; ε represents the heat generation rate on the surface of the busbar; σ represents the Stefan-Boltzmann constant.

(3) Solid Mechanics

The motion differential equation describing the motion of an object in a damped forced vibration system under the action of a disturbance force is:

分别表示整体坐标系下节点的位移、速度和加速度。In the formula, m is the total mass of the vibration system, C represents the viscous damping coefficient of the supporting vibration isolator when the object is moving, and K represents the force of the unit deformation of the spring stiffness. F ₀ sinωt represents the disturbance force received by the system, and the coordinate axis is placed on the static equilibrium position O of the object. x,

Respectively represent the displacement, velocity and acceleration of the node in the global coordinate system.

3. Set parameters and boundary conditions according to actual operating conditions

Electromagnetic field: Apply a rated current of 3.15kA to the A-phase, B-phase, and C-phase three-phase busbars respectively, with a phase difference of 120°, and set the three-phase busbars output from the cable room to ground. The contact impedance is set by changing the contact surface of the moving and static contact, the plum blossom contact and the conductivity of the circuit breaker contact surface, and the force calculation is added.

Solid heat transfer: set the ambient temperature as T to 293K, and set different convective heat transfer coefficients for different parts according to the actual operation of the switchgear; according to the surface air velocity, the convective cooling surface is divided into three parts:

The first part is the bus room with sufficient air circulation in the cabinet, and the convective heat transfer coefficient is 4W/(m ^2* *K); the second part is the inner part of the circuit breaker, and the convective heat transfer coefficient is 3W/(m ² *K) ); the third group is the cabinet and the base, the convective heat transfer coefficient is 5W/(m ² K).

Set the busbar to heat conduction; at the same time, set the surface heat radiation, set the radiation factor of the busbar to 0.4, and the radiation factor of the insulator to 0.8.

Solid Mechanics: Select the entire switchgear as the scope, and set the circuit breaker base, insulator support, and busbar ends as fixed constraints.

The material parameters of the present invention are shown in Table 1.

Table 1 Various material parameter table

Material copper epoxy resin Galvanized steel Thermal conductivity (W/m·K) 392 0.276 46 Density (g/cm³) 8.9 0.98 7.8 Specific heat capacity (J/(g·K)) 0.39 1.4 0.5 emissivity 0.4 0.8 0.8

4. Carry out grid division for the model based on the finite element method, and set the simulation time and step size: set the global grid size, further refine the grid according to the local geometric characteristics, and then build all the grids, and then Set the simulation time and step size, and start the calculation until the time condition is met, and the simulation result converges.

5. The present invention is based on the frequency domain-steady state research of the switchgear. First, the temperature distribution in the steady state is simulated as shown in Figure 3: the higher temperature points are concentrated at the circuit breaker and the plum blossom contact with poor ventilation. The hottest of these occurs at the connection of the circuit breaker.

The distribution of the electric field intensity is shown in Figure 4(1): the electric field intensity at the contact and the bend of the busbar is relatively large. The current density distribution is shown in Figure 4(2): the current is most concentrated at the connection of the circuit breaker, and the current density is relatively high at the bend of the plum blossom contact and the busbar. The skin effect of the busbar can be clearly seen, and the current is high. Concentrate on the surface of the busbar.

The distribution of the time-average Lorentz force on the three planes X, Y, and Z is shown in Figure 5: the part with the larger time-average Lorentz force is also the bend of the integrated circuit breaker, the plum contact and the busbar. Some parts need to be reinforced to prevent accidents caused by electrodynamic forces. Through simulation, the stress of other parts can be further explored and adjusted to improve the safety and stability of the switchgear.

Secondly, through simulation, compare and analyze the average temperature and maximum temperature of the switchgear when the ambient temperature is 293K, 298K, 303K, 308K, and 313K under rated working conditions, as shown in Figure 6: changing the ambient temperature under the same heat source and conditions does not affect The temperature distribution trend only affects the temperature rise. Comparing the calculated and related data, it can be seen that as the ambient temperature rises, the maximum temperature rise and the average temperature of the switchgear rise accordingly, and the relationship between the two is roughly linear.

6. Step S7 is specifically, through the interface of solid mechanics, setting different fixed constraints, and analyzing its influence on the displacement change of the busbar due to the force;

According to the coupling analysis of multi-physics fields, coupling solid heat transfer and solid mechanics, the influence of displacement caused by thermal expansion can be obtained as shown in Figure 7: (1) When the circuit breaker is fixed, the deformation of the busbar in the cable room and the busbar room is more obvious , the maximum displacement can reach 1.7mm; (2) When the insulator is fixed, the deformation of the busbar supported by the insulator is small, but the deformation of the circuit breaker and the busbar without support is more obvious, and the maximum displacement can reach 1.43mm; (3) when the fixed When the end of the busbar in the busbar room and the cable room is damaged, the bending of the circuit breaker and the busbar will be deformed significantly. The maximum displacement can reach 1.08mm.

To sum up, fixing the above parts is very important for the safe and stable operation of the switchgear, and can minimize the deformation of the busbar. At the same time, different fixed positions can be set to further explore the improvement of the stability of the busbar.

7. Step S8 is specifically to change the contact pressure at the connection through simulation, and then change the contact impedance, and analyze its influence on temperature rise and stress; as shown in Figure 8: whether it is at the plum blossom contact or at the The contact impedance at the circuit breaker is changed to change the pressure. The average temperature of this part is approximately linear with the change of the contact impedance. It can be seen from the figure that when the contact pressure becomes larger, the temperature rise of this part will be slightly reduced, which is beneficial to the switch. The stable operation of the cabinet;

Similarly, as shown in Figure 9, when two parts with different contact impedances are set, as the contact conductance increases, the average stress decreases with the increase of contact pressure, indicating that an appropriate increase in contact pressure can reduce the stress of the busbar Variety.

By adopting the method of the invention, the distribution characteristics of temperature rise, electric field intensity and electromotive force of the switchgear under different conditions can be simulated by modifying the current excitation and the characteristics of the material. The calculation results can analyze the operation of the switchgear, which can not only provide a theoretical basis for the optimal layout of the switchgear sensors, but also provide a basis for the engineering design optimization and heat dissipation structure design of the switchgear.

The above preferred embodiments are only to illustrate the technical solutions of the present invention, and are not limited thereto. Those skilled in the art can modify, replace or optimize the forms and details without departing from the scope of the claims. Wait for various changes. By adopting the method of the invention, the electric field intensity and the hottest temperature distribution characteristics of the switchgear under the influence of different factors, as well as the distribution characteristics of the electromotive force can be obtained.

Claims (9)

1. A method for obtaining the electric-thermal-stress distribution of switchgear under the influence of different factors, characterized in that it comprises: S1: Establish a simplified physical model of an electrical medium-voltage switchgear with multiple electrical rooms; S2: Theoretical analysis of switchgear involving electromagnetic field, temperature conduction and solid mechanics; S3: Add physical fields to conduct coupling analysis research of electromagnetic-heat transfer-solid mechanics; S4: Set appropriate physical parameters and various boundary conditions based on the actual operating state of the switchgear; S5: According to the geometric characteristics of each electrical room of the switchgear and the accuracy requirements of the calculation, mesh it, set the appropriate simulation time and step size, and set the solver according to the simulation requirements; S6: The distribution results of the electromagnetic field and temperature field in the steady state of the switchgear under different environmental conditions are obtained by simulation, and post-processing is performed to obtain the distribution of temperature, electric field intensity and electromotive force. Determine the location of the hottest point, and compare and analyze the impact of different environmental conditions on the maximum temperature and the average temperature; S7: Through the simulation, the change of the displacement of the busbar caused by the force due to the addition of different fixed constraints is obtained, and the influence on the stability of the busbar is analyzed; S8: Change the contact pressure at the connection through simulation, and analyze its influence on temperature rise and stress. 2. The simulation method for obtaining the electric-thermal-stress distribution of the switchgear under the influence of different factors according to claim 1, characterized in that: the three-dimensional physical model of the switchgear with multiple electrical rooms established in S1, with emphasis on circuit breakers , Conductive busbars, plum blossom contacts and other key components, while ignoring the fixing nuts and tiny electronic components that do not affect the accuracy of the analysis, the switchgear is reasonably simplified. 3. The simulation method for obtaining the electric-thermal-stress distribution of the switchgear under the influence of different factors according to claim 1, characterized in that: step S2 is specifically, the theoretical analysis of the electromagnetic field, temperature conduction and solid mechanics of the switchgear: according to the switchgear Maxwell's electromagnetic theory, heat conduction, heat convection, heat radiation and solid mechanics theory analysis of cabinet operation, select the simulation core physical field - electromagnetic field and solid heat transfer; at the same time consider the influence of stress on the mechanical structure, based on the selection of solid mechanics physics field. 4. A method for obtaining electric-thermal-stress distribution of switchgear under the influence of different factors according to claim 1, characterized in that: step S3 is specifically, adding relevant physical fields, and performing electromagnetic-temperature-solid mechanics multi- Physics coupling. Based on the above theoretical analysis, three physical fields of electromagnetic field, solid heat transfer and solid mechanics are added. Electromagnetic and temperature fields are coupled based on temperature and electromagnetic thermal effects; solid heat transfer and solid mechanics are coupled based on thermal expansion effects. 5. A method for obtaining electric-thermal-stress distribution of switchgear under the influence of different factors according to claim 1, characterized in that: Step S4 is specifically, setting corresponding parameters and boundary conditions based on the actual operating state of the switchgear: parameter Including electrical conductivity, magnetic permeability, resistivity, thermal conductivity and other relevant parameters such as electromagnetic, temperature and solid mechanics of each part of the switchgear; boundary conditions include external stress such as pressure, grounding, current excitation, temperature boundary, mechanical fixed constraints and so on. Environmental constraints. Add bidirectional coupling of temperature and material resistivity to improve simulation accuracy. 6. A method for obtaining the electrical-thermal-stress distribution of switchgear under the influence of different factors according to claim 1, characterized in that: step S5 is specifically divided into grids according to the geometric characteristics of the switch, and setting Simulation time and step size: set the global grid size, further refine the grid according to the local geometric features, and then build all the grids, then set the simulation time and step size, start calculation until the time condition is met, and the simulation results converge . 7. A method for obtaining electric-thermal-stress distribution of switchgear under the influence of different factors according to claim 1, characterized in that: step S6 is specifically, the electromagnetic field and temperature field obtained by simulation under the steady state of the switchgear Distribution results, and post-processing it to obtain the distribution of temperature, electric field strength and electromotive force. Determine the location of the hottest spot, and compare and analyze the influence of environmental conditions on the hottest spot temperature and the average temperature. 8. A method for obtaining electric-thermal-stress distribution of switchgear under the influence of different factors according to claim 1, characterized in that: step S7 is specifically, adding different fixed constraints obtained through simulation, and analyzing the stress caused by the busbar Changes in displacement. 9. A method for obtaining the electric-thermal-stress distribution of the switchgear under the influence of different factors according to claim 1, characterized in that: step S8 is specifically to change the contact pressure at the connection through simulation, and then change the contact impedance, Analyze its influence on temperature rise and its influence on stress.

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