A multi-factor integrated SF6 alternative gas suitability assessment method

Abstract

The present invention provides a multi-factor fusion SF 6 The invention discloses a method for evaluating the applicability of alternative gases, which relates to the field of electrical technology, and includes: obtaining alternative gases based on gas insulation, and performing material parameters for electric field, temperature field and vibration physical field simulations; establishing a simplified simulation model based on disconnector equipment, and establishing a cube physical field simulation calculation domain outside the simplified simulation model; obtaining boundary conditions, and performing electric field simulation, temperature field simulation and vibration simulation in the physical field simulation calculation domain based on the boundary conditions and material parameters to obtain a maximum field strength modulus, a maximum temperature rise value and a maximum acceleration value; obtaining a factor evaluation value based on the greenhouse effect potential value, recycling difficulty, availability, price value and a preset component factor evaluation formula of the alternative gases; obtaining a comprehensive evaluation value based on the factor evaluation value and a preset comprehensive factor evaluation formula, and when the comprehensive evaluation value is greater than a preset threshold value, the alternative gas is used as the SF in the GIS. 6 alternative gases.

Description

Technical Field

[0001] The present invention relates to the field of electrical technology, and in particular to a multi-factor integrated SF6 alternative gas applicability assessment method. Background Art

[0002] Because SF6 has excellent insulation properties, its insulation strength is much higher than that of air and transformer oil under certain conditions, which makes SF6 widely used in GIS today to ensure safe and stable operation of the equipment. At the same time, SF6 gas has excellent convection heat dissipation characteristics, which makes the arc temperature drop quickly and the arc easy to extinguish, thus ensuring the stability and reliability of GIS during switch operation. However, the greenhouse effect potential value of SF6 is as high as 25,000, which is an extremely strong greenhouse gas. In addition, SF6 is extremely difficult to decompose. Once it leaks into the air, it will remain for a long time and will continue to cause huge pollution to the environment. At the same time, with the increase in restrictions on the use of SF6 gas, its price has also shown an increasingly rapid growth trend. Therefore, finding environmentally friendly alternatives to SF6 in GIS is of great significance for reducing greenhouse gas emissions, protecting the earth's environment, reducing the cost of GIS equipment, and improving economic benefits.

[0003] At present, although researchers have paid attention to the insulation performance, environmental performance and economy of alternative gases, they often focus too much on one aspect and ignore other equally important factors. For example, some studies may overemphasize the insulation performance of alternative gases and ignore their environmental impact or production costs; or some studies may pay too much attention to the environmental protection of alternative gases and ignore their stability and reliability in practical applications. At the same time, existing research generally focuses on SF6 alternative gases, lacks specific research on SF6 alternative gases in GIS equipment, and is not applicable to the improvement of SF6 insulating gas in GIS. In addition, there is a lack of quantitative research in the feasibility study of SF6 alternative gases. The lack of quantitative formulas makes it difficult to evaluate the feasibility of SF6 alternative gases. Without quantitative formulas, it can only be judged by experience or qualitative analysis, which will lead to low accuracy and objectivity of the results.

[0004] Therefore, it is urgent to provide a solution to improve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a multi-factor integrated SF6 alternative gas suitability assessment method to improve the existing technology lack of research on the feasibility of SF6 alternative gas and lack of quantitative formulas, and can only rely on empirical judgment or qualitative analysis, resulting in low accuracy and objectivity of the results.

[0006] The present invention provides a multi-factor integrated SF6 alternative gas applicability assessment method, comprising the following steps:

[0007] Acquire alternative substitute gases based on gas insulation, and acquire material parameters for electric field, temperature field and vibration physical field simulations based on the alternative substitute gases;

[0008] A simplified simulation model is established based on the disconnector device, and a cube physical field simulation calculation domain is established outside the simplified simulation model;

[0009] Obtaining boundary conditions, and obtaining maximum field strength modulus, maximum temperature rise value, and maximum acceleration value after performing electric field simulation, temperature field simulation, and vibration simulation in the physical field simulation calculation domain based on the boundary conditions and material parameters;

[0010] Obtaining factor evaluation values ​​of the candidate alternative gas based on the greenhouse effect potential value, recycling difficulty, availability value, price value and a preset component factor evaluation formula of the candidate alternative gas, wherein the factor evaluation values ​​include: electric field value, temperature rise value, vibration value, temperature effect value, recycling difficulty value, availability value and price value;

[0011] A comprehensive evaluation value is obtained based on the factor evaluation value and a preset comprehensive factor evaluation formula. When the comprehensive evaluation value is greater than a preset threshold, the alternative alternative gas is used as an alternative gas to SF6 in the GIS.

[0012] The beneficial effect of the multi-factor integrated SF6 alternative gas applicability assessment method provided by the present invention is that the present invention comprehensively evaluates the performance of alternative gases in GIS by deriving technical parameters, environmental parameters and economic parameters, and provides a factor assessment formula for calculating the influence value of each factor and a comprehensive factor assessment formula for calculating the comprehensive assessment value of SF6 alternative gas, which provides a favorable criterion for finding SF6 alternative gases in GIS.

[0013] Optionally, the alternative alternative gas includes: N2, CO2, C4F7N;

[0014] Optionally, the expression of the factor evaluation value is:

[0015] ;

[0016] in, , to They represent the electric field value factor value, temperature rise value factor value, vibration value factor value, temperature effect value factor value, recycling difficulty value factor value, availability value factor value, and price value factor value respectively. , and They are the maximum field strength, maximum temperature rise, and maximum acceleration values ​​allowed by the equipment. , , and They are the greenhouse effect value, recycling difficulty value, availability value and price value of SF6 gas. , and They are the maximum field strength, maximum temperature rise, and maximum acceleration values ​​obtained by simulation when the equipment uses alternative gas as insulating gas. , , and They are the greenhouse effect value, recycling difficulty value, availability value and price value of the alternative gas;

[0017] The expression of the comprehensive evaluation value is:

[0018] ;

[0019] in, Indicates the comprehensive evaluation value.

[0020] Optionally, the boundary condition consists of a first boundary condition, a second boundary condition and a third boundary condition, wherein:

[0021] The first boundary condition is:

[0022] ;

[0023] in, is the electric field strength, is the electric flux density, is the charge density, is the Hamiltonian operator;

[0024] The second boundary condition is:

[0025] ;

[0026] ;

[0027] in, is the heat flux density; is the heat flow; is the area of ​​the plate perpendicular to the direction of heat conduction; is the thermal conductivity; represents the temperature gradient; is the convective heat transfer coefficient; is the temperature-pressure difference between the wall temperature and the fluid temperature;

[0028] The third boundary condition is:

[0029] ;

[0030] in, represents the Lorentz force acting on the disconnector, represents the current density, Represents the magnetic flux density.

[0031] Optionally, during the process of performing electric field simulation, temperature field simulation and vibration simulation in the physical field simulation calculation domain, a non-uniform grid division method is used to mesh the device casing and the cube physical field simulation calculation domain, refine the three-phase coil and double contacts, and coarsen the device casing.

[0032] Optionally, the preset threshold is 0.6, and only when the comprehensive evaluation value is greater than 0.6 can it be determined that the alternative alternative gas can be used as a substitute gas for SF6 in GIS.

[0033] Optionally, after establishing a simplified simulation model based on the disconnector device, it is necessary to build a thin wall that is the same as the current status of the outer shell close to the inner wall of the outer shell to simulate the alternative alternative gas filled into the GIS, and to change the alternative alternative gas inside the double-break disconnector in the GIS by setting different material parameters for the gas in the thin wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a flow chart of a multi-factor integrated SF6 alternative gas applicability assessment method provided by the present invention;

[0035] Figure 2 It is a schematic diagram of an external housing model of a double-break disconnector provided by the present invention;

[0036] Figure 3 The present invention provides a flow chart for verifying the feasibility of SF6 replacement gas in GIS by considering multiple factors;

[0037] Figure 4 This is a surface electric field distribution diagram of a double-break disconnector housing using N2 as insulating gas provided by the present invention;

[0038] Figure 5 This is a diagram of the electric field distribution on the conductor surface of a double-break disconnector using N2 as the insulating gas provided by the present invention;

[0039] Figure 6 This is a surface electric field distribution diagram of an insulating component of a double-break disconnector using N2 as insulating gas provided by the present invention;

[0040] Figure 7 It is a temperature distribution diagram of a double-break disconnector provided by the present invention using N2 as insulating gas;

[0041] Figure 8 It is a distribution diagram of the vibration effective acceleration magnitude of the double-break disconnector using N2 as the insulating gas provided by the present invention. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0043] The embodiment of the present invention provides a multi-factor integrated SF6 alternative gas applicability assessment method, see Figure 1 , including the following steps:

[0044] S1. Obtaining a candidate alternative gas based on gas insulation, and obtaining material parameters for electric field, temperature field and vibration physical field simulation based on the candidate alternative gas;

[0045] S2. Establishing a simplified simulation model based on the disconnector device, and establishing a cube physical field simulation calculation domain outside the simplified simulation model;

[0046] S3, obtaining boundary conditions, and obtaining the maximum field strength modulus, maximum temperature rise value and maximum acceleration value after performing electric field simulation, temperature field simulation and vibration simulation in the physical field simulation calculation domain based on the boundary conditions and material parameters;

[0047] S4. Obtaining factor evaluation values ​​of the candidate alternative gas based on the greenhouse effect potential value, recycling difficulty, availability value, price value and a preset component factor evaluation formula of the candidate alternative gas, wherein the factor evaluation values ​​include: electric field value, temperature rise value, vibration value, temperature effect value, recycling difficulty value, availability value and price value;

[0048] S5. Obtain a comprehensive evaluation value based on the factor evaluation value and a preset comprehensive factor evaluation formula. When the comprehensive evaluation value is greater than a preset threshold, use the alternative alternative gas as a substitute gas for SF6 in GIS.

[0049] In some embodiments, when executing step S1, the alternative replacement gas includes: N2, CO2, C4F7N.

[0050] In some embodiments, when executing step S2, the simplified simulation model mainly includes moving and static contacts, an auxiliary earthing switch, an insulating basin and a shell. The overall shell size of the model is: 1.160m long, 0.658m wide, and 1.035m high. The moving contact is made of ɸ68 T2-Y copper rod material as a whole, and copper tungsten contacts are installed on the ends to improve the burn resistance; each moving contact has 2 guide sleeves, 1 guide sleeve close to the gear and 1 guide sleeve at the end. The distance between the two guide sleeves is 250mm. The stroke of the auxiliary earthing switch moving contact is 145cm±5mm, and the center insert of the insulating basin is made of aluminum alloy with a diameter of 90mm.

[0051] Furthermore, the cube physical field simulation calculation domain is a cube calculation domain with a side length of 2m.

[0052] In some embodiments, after executing step S2 to establish a simplified simulation model based on the disconnector device, it is necessary to establish a thin wall that is the same as the current state of the outer shell close to the inner wall of the outer shell to simulate the alternative alternative gas filled into the GIS, and the alternative alternative gas inside the double-break disconnector in the GIS can be changed by setting different material parameters for the gas in the thin wall.

[0053] In fact, the alternative gas is the insulating gas.

[0054] In some embodiments, when executing step S3, during the process of performing electric field simulation, temperature field simulation and vibration simulation in the physical field simulation calculation domain, a non-uniform grid division method is used to mesh the device casing and the cube physical field simulation calculation domain, the three-phase coil and double contacts are refined, and the device casing is coarsened.

[0055] In fact, due to the complex structure of the simulation model of the double-break disconnector of the present invention, if the uniform grid division method is used to divide the non-main parts of the equipment with the same fine grid division, the total number of grids after division can reach 29837126, which will lead to a large number of overall grid divisions, increased difficulty in numerical solution, and reduced solution efficiency. However, the non-uniform grid division method is used to divide the non-main parts such as the equipment casing and the external cube calculation domain with a larger free tetrahedral grid, and the overall number of grids is reduced to 7409269, which is conducive to reducing the overall number of grids, ensuring accuracy while improving the calculation rate.

[0056] Specifically, when executing step S3 to perform electric field simulation, the electric field distribution of each part at the moment when the overall field strength is maximum is simulated, and voltage excitations with module values ​​of 110KV, 55KV and -110KV are applied to the three contacts of the double-break disconnector respectively, and the auxiliary grounding switch is in the disconnected state.

[0057] In some embodiments, when executing step S4, the factor evaluation values ​​can be divided into three categories: technical parameters, environmental parameters and economic parameters. Among them, technical parameters include electric field values, temperature rise values ​​and vibration evaluation values, environmental parameters include greenhouse effect values ​​and recycling difficulty values, and economic parameters include availability values ​​and price values.

[0058] Specifically, in the calculation of the electric field value, temperature rise value and vibration evaluation value included in the technical parameters, the maximum value allowed by the equipment is taken as the base value, and the difference between the simulation result value and the base value is taken as the actual value; in the calculation of environmental protection parameters and economic parameters, the value corresponding to SF6 is taken as the base value, and the difference between the alternative gas and the base value is taken as the actual value to calculate the factor evaluation value.

[0059] Furthermore, the preset component factor evaluation formula is used to calculate the factor evaluation value, and the expression of the factor evaluation value is:

[0060] ;

[0061] in, , to They represent the electric field value factor value, temperature rise value factor value, vibration value factor value, temperature effect value factor value, recycling difficulty value factor value, availability value factor value, and price value factor value respectively. , and They are the maximum field strength, maximum temperature rise, and maximum acceleration values ​​allowed by the equipment. , , and They are the greenhouse effect value, recycling difficulty value, availability value and price value of SF6 gas. , and They are the maximum field strength, maximum temperature rise, and maximum acceleration values ​​obtained by simulation when the equipment uses alternative gas as insulating gas. , , and They are the greenhouse effect value, recycling difficulty value, availability value and price value of the alternative gas.

[0062] The technical parameters of the double-break disconnector gas chamber in GIS after replacing the insulating gas are the main indicators for verifying the feasibility of the SF6 alternative gas. Therefore, the evaluation values ​​of the three factors of electric field, temperature and vibration included in the technical parameters each account for 20% of the comprehensive value for verifying the feasibility of SF6 alternative gas; the environmental protection and economy of SF6 alternative gas are also objects that need to be considered in practical applications. Therefore, the four factors included in these two parameters: greenhouse effect value, recycling difficulty value, availability value and price value each account for 10%. According to the proportion, the comprehensive evaluation value of the feasibility of SF6 alternative gas in GIS is obtained. The expression of the comprehensive evaluation value is:

[0063] ;

[0064] in, Indicates the comprehensive evaluation value.

[0065] In some embodiments, when executing step S3, the boundary condition consists of a first boundary condition, a second boundary condition and a third boundary condition.

[0066] Specifically, the first boundary condition is the Maxwell equations consisting of Ampere's circuit law, Faraday's law of electromagnetic induction, Gauss's electric flux law and Gauss's magnetic flux law, which are expressed in partial differential form as follows:

[0067] ;

[0068] in, is the electric field strength, is the electric flux density, is the charge density, is the Hamiltonian operator.

[0069] Specifically, the electromagnetic loss is used as a heat source to load the moving and static contacts of the simulation model, the initial fluid and ambient temperature are set to 30°C, the temperature rise rate is 5k / min, the fluid normal inflow velocity is 0.01m / s, and considering the influence of gravity, according to heat transfer theory, there are three basic ways of heat energy transfer: heat conduction, heat convection and heat radiation. Heat radiation has little effect on the simulation results of the model, so the present invention ignores the influence of heat radiation.

[0070] Furthermore, the second boundary condition is obtained by combining the heat flux and the convective heat transfer coefficient obtained by temperature rise calculation using the Fluid-Solid-Temperature multiphysics coupling interface.

[0071] Specifically, according to Fourier's law, the expression of heat flux is:

[0072] ;

[0073] Furthermore, according to Newton's cooling formula, the convective heat transfer coefficient can be expressed as:

[0074] ;

[0075] in, is the heat flux density; is the heat flow; is the area of ​​the plate perpendicular to the direction of heat conduction; is the thermal conductivity; represents the temperature gradient; is the convective heat transfer coefficient; is the temperature-pressure difference between the wall temperature and the fluid temperature;

[0076] Furthermore, the third boundary condition is obtained by vibration simulation calculation based on the magnetic field-solid mechanics multiphysics coupling interface.

[0077] Specifically, add a 1600A three-phase current with a frequency of 50Hz to the conductive loop, set the device's external connection boundary to magnetic insulation, add a fixed boundary condition to the surface of the bottom of the disconnector that contacts the ground, and set all other parts to free movement. Charged particles moving in an electromagnetic field are affected by electromagnetic forces. Therefore, the current-carrying conductor moves in an electromagnetic field under the influence of electromagnetic forces. The electromagnetic force on the disconnector is the Lorentz force. The formula for the third boundary condition is as follows:

[0078] ;

[0079] in, represents the Lorentz force on the disconnector, represents the current density, Represents the magnetic flux density.

[0080] In some embodiments, see Figure 2 , a simulation model of a double-break disconnector in a GIS is established. In order to verify whether one or more of the alternative alternative gases (N2, CO2, C4F7NS) can be used as a substitute gas for SF6, the present invention takes N2 as an example, sets the internal gas chamber gas from SF6 to N2, sets appropriate boundary conditions, and performs electric field simulation, temperature field simulation, and vibration simulation on the model in turn. If the maximum field strength modulus, maximum temperature rise value, and maximum acceleration value obtained by simulation all meet their respective first boundary conditions, second boundary conditions, and third boundary conditions, then all factor evaluation values ​​are brought into the preset comprehensive factor evaluation formula proposed in the present invention in combination with environmental protection parameters and economic parameters to verify the feasibility of N2 as a substitute gas for SF6.

[0081] In some embodiments, when executing step S5, the preset threshold is 0.6. Only when the comprehensive evaluation value is greater than 0.6 can it be determined that the alternative alternative gas can be used as an alternative gas for SF6 in GIS.

[0082] In some embodiments, see Figure 3 First, create a 3D model and set material parameters, divide the grid in a non-uniform way, set different boundary conditions to perform electric field simulation, temperature simulation and vibration simulation in turn. If any of the electric field simulation, temperature simulation and vibration simulation does not meet the corresponding design conditions, it is directly judged that the alternative alternative gas cannot be used as a SF6 alternative gas.

[0083] Furthermore, the temperature rise effect value, recovery difficulty value, availability value and price value of the alternative alternative gas are obtained by consulting the data and brought into the empirical formula (i.e., the preset comprehensive factor evaluation formula proposed in the present invention) to obtain the output value, and whether the value is greater than 0.6 is judged. When the output value is greater than 0.6, it is judged that the alternative alternative gas can be used as an SF6 alternative gas, otherwise it cannot be used as an SF6 alternative gas.

[0084] See also Figure 4 , Figure 5 , Figure 6 , are the electrostatic distribution diagrams of the shell, conductor and insulating parts of the double-break disconnector using N2 gas as the insulating gas under the closed condition. It can be seen that the maximum surface field strength modulus values ​​are 12.4 kV / mm, 16.1 kV / mm, and 11.4 kV / mm, respectively, which all meet the design value requirements (16kV / mm, 25 kV / mm, 12kV / mm).

[0085] The maximum field strength value obtained by simulating each part and the maximum field strength allowed by the corresponding device are sequentially substituted into the factor evaluation formula proposed by the present invention to obtain the evaluation values ​​of the shell, conductor and insulator, which are 0.225, 0.356 and 0.05 respectively. The average value of the field strength modulus of each component is taken to obtain the electric field evaluation value, which is 0.21.

[0086] See also Figure 7 It can be seen that the maximum temperature is 78.8°C and the initial ambient temperature is 30°C, so the maximum temperature rise is 48.8°C at this time, which meets the design value requirement of the maximum temperature rise of 60°C. The simulated maximum temperature rise value and the maximum temperature rise value allowed by the equipment are brought into the factor evaluation formula proposed in the present invention to obtain the temperature evaluation value, which is 0.187.

[0087] See also Figure 8 , we can know that the maximum effective acceleration value is 0.18m / s 2 , the maximum effective acceleration value that meets the design requirements is 0.25m / s 2The simulated maximum effective acceleration value and the maximum effective acceleration value allowed by the device are substituted into the factor evaluation formula proposed by the present invention to obtain a vibration evaluation value of 0.28.

[0088] When obtaining environmental parameters, the greenhouse effect value is calculated using GWP (greenhouse potential). The GWP value of SF6 is as high as 25,000, while the GWP value of N2 is 0. Substituting it into the formula, the greenhouse effect value of N2 is 1. Since N2 exists in large quantities in the air, the difficulty value of N2 recovery is defined as 1. When obtaining economic parameters, the price of 1L of SF6 gas is 310 yuan, while the price of 1L of high-purity N2 gas is only 81.25 yuan. Substituting it into the comprehensive factor evaluation formula, the price value is 0.738. Nitrogen accounts for 78% of the air, so the obtainable value of N2, the SF6 alternative gas, is defined as 0.78.

[0089] The obtained factor evaluation values ​​are substituted into the comprehensive factor evaluation formula proposed in the present invention to calculate the comprehensive evaluation value of SF6 replacing gas N2, which is 0.4872, less than the defined standard of 0.6. Therefore, it can be evaluated that N2 cannot be used as a substitute gas for SF6 in GIS.

[0090] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A multi-factor SF6 alternative gas suitability assessment method, characterized in that: include: Acquire alternative substitute gases based on gas insulation, and acquire material parameters for electric field, temperature field and vibration physical field simulations based on the alternative substitute gases; A simplified simulation model is established based on the disconnector device, and a cube physical field simulation calculation domain is established outside the simplified simulation model; Obtaining boundary conditions, and obtaining maximum field strength modulus, maximum temperature rise value, and maximum acceleration value after performing electric field simulation, temperature field simulation, and vibration simulation in the physical field simulation calculation domain based on the boundary conditions and material parameters; Obtaining factor evaluation values ​​of the candidate alternative gas based on the greenhouse effect potential value, recycling difficulty, availability value, price value and a preset component factor evaluation formula of the candidate alternative gas, wherein the factor evaluation values ​​include: electric field value, temperature rise value, vibration value, temperature effect value, recycling difficulty value, availability value and price value; A comprehensive evaluation value is obtained based on the factor evaluation value and a preset comprehensive factor evaluation formula. When the comprehensive evaluation value is greater than a preset threshold, the alternative alternative gas is used as a substitute gas for SF6 in the GIS, wherein the preset component factor evaluation formula is used to calculate the factor evaluation value, and the expression of the factor evaluation value is: ； in, , to They represent the electric field value factor value, temperature rise value factor value, vibration value factor value, temperature effect value factor value, recycling difficulty value factor value, availability value factor value, and price value factor value respectively. , and They are the maximum field strength, maximum temperature rise, and maximum acceleration values ​​allowed by the equipment. , , and They are the greenhouse effect value, recycling difficulty value, availability value and price value of SF6 gas. , and They are the maximum field strength, maximum temperature rise, and maximum acceleration values ​​obtained by simulation when the equipment uses alternative gas as insulating gas. , , and They are the greenhouse effect value, recycling difficulty value, availability value and price value of the alternative gas; The technical parameters of the double-break disconnector gas chamber in GIS after replacing the insulating gas are the main indicators for verifying the feasibility of the SF6 alternative gas. Therefore, the evaluation values ​​of the three factors of electric field, temperature and vibration included in the technical parameters each account for 20% of the comprehensive value for verifying the feasibility of SF6 alternative gas; the environmental protection and economy of SF6 alternative gas are also objects that need to be considered in practical applications. Therefore, the four factors included in these two parameters: greenhouse effect value, recycling difficulty value, availability value and price value each account for 10%. According to the proportion, the comprehensive evaluation value of the feasibility of SF6 alternative gas in GIS is obtained. The expression of the comprehensive evaluation value is: ； in, Indicates the comprehensive evaluation value.

2. A multi-factor SF6 alternative gas suitability assessment method according to claim 1, characterized in that: The alternative substitute gases include: N2, CO2, and C4F7N.

3. The multi-factor SF6 alternative gas suitability assessment method according to claim 1 is characterized in that: The boundary conditions consist of a first boundary condition, a second boundary condition and a third boundary condition, wherein: The first boundary condition is: ； in, is the electric field strength, is the electric flux density, is the charge density, is the Hamiltonian operator; The second boundary condition is: ； ； in, is the heat flux density; is the heat flow; is the area of ​​the plate perpendicular to the direction of heat conduction; is the thermal conductivity; represents the temperature gradient; is the convective heat transfer coefficient; is the temperature-pressure difference between the wall temperature and the fluid temperature; The third boundary condition is: ； in, represents the Lorentz force acting on the disconnector, represents the current density, Represents the magnetic flux density.

4. The multi-factor fusion SF6 alternative gas suitability assessment method according to claim 1 is characterized in that: In the process of performing electric field simulation, temperature field simulation and vibration simulation in the physical field simulation calculation domain, a non-uniform meshing method is used to mesh the device housing and the cube physical field simulation calculation domain, refine the meshing of the three-phase coil and the double contacts, and coarsen the meshing of the device housing.

5. The multi-factor fusion SF6 alternative gas suitability assessment method according to claim 1 is characterized in that: The preset threshold is 0.

6. Only when the comprehensive evaluation value is greater than 0.6 can it be determined that the alternative alternative gas can be used as a substitute gas for SF6 in GIS.

6. The multi-factor SF6 alternative gas suitability assessment method according to claim 1 is characterized in that: After establishing a simplified simulation model based on the disconnector equipment, it is necessary to build a thin wall that is the same as the current status of the shell close to the inner wall of the shell to simulate the alternative gas filled into the GIS. By setting different material parameters for the gas in the thin wall, the alternative gas inside the double-break disconnector in the GIS can be changed.

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