Method for evaluating and calculating electrical connection operation state of transformer bushing

Abstract

The invention relates to the technical field of transformer bushings, in particular to a transformer bushing electric connection operation state evaluation and calculation method, which comprises the following steps: establishing a geometric model comprising a bushing electric connection core assembly which at least comprises a conductive tube for realizing electric connection and a bushing internal extension conductive tube, matching parameters are set according to the electric connection matching relation of the two; assigning a mechanical attribute meeting a displacement calculation precision requirement for each component in the geometric model; applying a constraint condition and an operation load conforming to an actual application scene of the sleeve to the geometric model, calculating the displacement of each component in the geometric model by adopting a finite element method, and in the calculation process, setting the contact relationship between the conductive tube and the extended conductive tube in the sleeve to be irrelevant, and setting the contact relationship between the other components to be bound; according to the invention, the electrical connection state can be evaluated in the bushing design stage, the traditional post-operation detection is replaced, the overheating and discharge risks are avoided in advance, and the disassembly of a real object or the waiting of a temperature rise signal is not needed.

Description

Technical Field

[0001] This invention relates to the field of transformer bushing technology, and in particular to a method for evaluating and calculating the operating status of transformer bushing electrical connections. Background Technology

[0002] Oil-immersed power transformers are crucial equipment in power systems, and their operation is directly related to the safety of the entire power grid. Bushings, as components that deliver voltage and carry high currents, are widely used in power transformers. High-voltage bushings for 110kV and above oil-immersed transformers mostly use capacitive bushings. Their internal structure consists of a capacitor core (alternating layers of insulating paper and aluminum foil), typically wound onto a conductive tube. The diameter and length of the capacitor core are related to the voltage level. Simultaneously, to meet external insulation requirements, the length of the insulator on the air side of the bushing needs to be selected based on the arc distance or creepage distance. This creates a matching relationship between the length of the internal capacitor core and the length of the external insulation. Generally, the insulation requires a shorter distance due to the controllable operating environment, while the external insulation needs a longer distance to withstand adverse effects such as rain, pollution, and high altitude. Using a full-length conductive tube for the capacitor core winding increases production difficulty. The common practice in industry is to use a short conductive tube to roll up the capacitor core, and then connect the conductive tubes internally by setting electrical connections inside the sleeve to extend the conductive tube and meet the external insulation requirements.

[0003] Common electrical connections include watchband contacts and spring contacts. The optimal operating state for these contacts is a perfectly aligned, axisymmetric state. Once the bushing is installed in a non-vertical state, due to gravity, the components of the bushing will not be perfectly aligned. Considering the weight of external lead fittings, the mating parts will also have relative displacement, causing the contacts to operate in a non-aligned state.

[0004] Currently, determining the operational status of the internal electrical connections of bushings requires either online inspection or power outage maintenance after the bushing has been in operation for a period of time. Online inspection typically requires the bushing electrical connections to exhibit some deterioration, resulting in a higher temperature rise, which is detected during thermal imaging or precise temperature measurement. During power outage maintenance, the bushing can be opened to directly observe whether the internal electrical connections have deteriorated.

[0005] However, both of these methods can only be implemented after the bushing is put into actual operation, which is costly and lacks the ability to predict in advance. Therefore, a method for evaluating and calculating the operating status of transformer bushing electrical connections is proposed, which can be evaluated in advance during the design phase and corresponding improvement measures can be taken. Summary of the Invention

[0006] In view of the lack of research in the existing technology, the technical problem to be solved by the present invention is that the operating state of the internal electrical connection of the bushing disclosed in the existing technology is difficult to predict in advance, which leads to the technical bottleneck that the bushing cannot be targeted for improvement in advance during the design stage.

[0007] The above-mentioned technical problems are solved by the following technical solution: This invention proposes a method for evaluating and calculating the operating status of transformer bushing electrical connections, including,

[0008] Establish a geometric model that includes the core components of the sleeve electrical connection. The core components include at least a conductive tube for realizing the electrical connection and an extended conductive tube inside the sleeve, and set the mating parameters according to the electrical connection mating relationship between the two.

[0009] Assign mechanical properties to each component in the geometric model to meet the requirements of displacement calculation accuracy;

[0010] The geometric model is subjected to constraints and operating loads that conform to the actual application scenario of the casing;

[0011] The displacement of each component in the geometric model is calculated using the finite element method. During the calculation, the contact relationship between the conductive tube and the extended conductive tube inside the sleeve is set to be irrelevant, and the contact relationship between the other components is set to be bound.

[0012] Read the displacement calculation results and determine whether the displacement difference between the conductive tube and the mating part of the extended conductive tube inside the sleeve exceeds the mating parameter;

[0013] If the condition does not exceed the limit, the operating status of the bushing electrical connection is deemed qualified.

[0014] If the displacement exceeds the specified parameters, the interference characteristics of the two components are analyzed, and the above steps are repeated until the displacement difference does not exceed the specified fitting parameters.

[0015] In a preferred embodiment of the transformer bushing electrical connection operation status evaluation calculation method of the present invention: the core components of the geometric model include capacitor core, mounting flange, air-end hollow insulator, insulator mounting flange, insulator end cover and bushing air-end terminal, and the relative positions of each component are consistent with the actual bushing assembly relationship.

[0016] In a preferred embodiment of the transformer bushing electrical connection operation status evaluation calculation method of the present invention: the fitting parameters include the insertion depth of the conductive tube and the extended conductive tube inside the bushing and the fitting gap, wherein the fitting gap is the maximum allowable displacement difference at the fitting point of the two.

[0017] In a preferred embodiment of the transformer bushing electrical connection operation status evaluation calculation method of the present invention: the mechanical properties include at least the density, elastic modulus and Poisson's ratio of the component material, and the material properties of each component match the mechanical properties of the corresponding component of the actual bushing.

[0018] In a preferred embodiment of the transformer bushing electrical connection operation status evaluation calculation method of the present invention: the constraint condition is to apply a fixed constraint to the bushing mounting flange;

[0019] The operating load includes the gravity load applied to all components, as well as the external load applied to the air terminal 8 of the bushing. The external load corresponds to the force generated by the external connecting hardware, shielding ring and wires during actual operation.

[0020] In a preferred embodiment of the transformer bushing electrical connection operation status assessment calculation method of the present invention: when calculating displacement using the finite element method, the coupling effect of gravity load and external load is incorporated into the finite element calculation process.

[0021] In a preferred embodiment of the transformer bushing electrical connection operation status evaluation calculation method of the present invention: the interference feature includes adjusting at least one parameter among the bushing structure, component material or the operating load.

[0022] In a preferred embodiment of the transformer bushing electrical connection operation status assessment and calculation method of the present invention, the specific method for determining whether the displacement difference exceeds the matching parameters is as follows:

[0023] Extract the relative displacement difference Δδ between the conductive tube and the extended conductive tube inside the sleeve in the electrical connection area;

[0024] Compare |Δδ| with the fit clearance Δg in the fit parameters;

[0025] If |Δδ|≤Δg, then it is deemed qualified;

[0026] If |Δδ|>Δg, then it is deemed unqualified and proceeds to the interference feature analysis stage.

[0027] In a preferred embodiment of the transformer bushing electrical connection operation status assessment and calculation method of the present invention, the specific method of interference feature analysis is as follows:

[0028] The type of interference can be distinguished based on the relative deformation trend of the conductive tube and the extended conductive tube inside the sleeve:

[0029] If the downward deformation of the conductive tube is greater than the downward deformation of the extended conductive tube inside the sleeve, it is an interference of the first kind.

[0030] If the downward deformation of the conductive tube is less than the downward deformation of the extended conductive tube inside the sleeve, it is considered a second type of interference.

[0031] In a preferred embodiment of the transformer bushing electrical connection operation status assessment and calculation method of the present invention: the adjustment method for the interference type is as follows:

[0032] For the first type of interference, adjust the stiffness of the air-end hollow insulator;

[0033] For the second type of interference, adjust the external load on the air end terminal of the bushing or the stiffness of the air end hollow insulator;

[0034] The stiffness adjustment is achieved by modifying the material properties or structural form of the air-end hollow insulator, and the external load adjustment is achieved by optimizing the structure or weight of the external connection components.

[0035] The beneficial effects of this invention are as follows: This invention can evaluate the electrical connection status during the sleeve design stage, replacing the traditional post-operation testing, thus avoiding the risks of overheating and discharge in advance, without the need to disassemble the physical object or wait for the temperature rise signal; in finite element modeling, it simplifies the contact relationship between the conductive tube and the extended conductive tube, reduces nonlinear problems, and greatly improves computational efficiency; it covers multiple installation tilt angles and load conditions, automatically distinguishes interference types and outputs optimized solutions, which can ensure electrical connection safety and shorten the research and development cycle. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention.

[0037] Figure 1 A schematic diagram of the overall structure of the transformer bushing is shown.

[0038] Figure 2 It shows Figure 1 Enlarged view of point A in the middle.

[0039] Figure 3 A reference diagram showing the constraints and operating loads of a transformer bushing in a real-world application scenario is presented.

[0040] Figure 4 The state reference diagram for interference mode 1 is shown.

[0041] Figure 5 A state reference diagram for interference mode 2 is shown.

[0042] Figure 6 A reference schematic diagram of the established geometric model of the casing is shown.

[0043] Figure 7It shows Figure 6 Enlarged view of the connection between the inner conductive tube and the sleeve of the conductive tube.

[0044] Figure 8 A reference diagram showing the installation angle and load of the bushing is provided.

[0045] Figure 9 The graph showing the displacement calculation results is displayed.

[0046] Figure 10 It shows Figure 9 Enlarged view of the connection between the inner conductive tube and the sleeve of the conductive tube.

[0047] Figure 11 The diagram shows the displacement calculation results after reducing the tension at the terminal.

[0048] In the picture:

[0049] 1. Capacitor core;

[0050] 2. Conductive tube; 21. Guide cone;

[0051] 3. Install the flange;

[0052] 4. Air-end hollow insulator;

[0053] 5. Insulator mounting flange;

[0054] 6. Extend the conductive tube inside the sleeve;

[0055] 7. Insulator end caps;

[0056] 8. Air terminal block of the bushing;

[0057] 9. Touching fingers. Detailed Implementation

[0058] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0059] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0060] Reference Figures 1-5 This embodiment provides a method for evaluating and calculating the operating status of transformer bushing electrical connections, including:

[0061] S1: Establish a geometric model containing the core components of the sleeve electrical connection. The core components include at least the conductive tube 2 for realizing the electrical connection and the extended conductive tube 6 inside the sleeve, and set the mating parameters according to the electrical connection mating relationship between the two.

[0062] The geometric model includes core components such as capacitor core 1, mounting flange 3, air-end hollow insulator 4, insulator mounting flange 5, insulator end cover 7, and bushing air-end terminal block 8. The relative positions of each component correspond to the actual bushing assembly. The assembly state of the geometric model can be referenced. Figure 1 and Figure 2 .

[0063] It should be noted that the end of the conductive tube 2 is provided with a guide cone 21.

[0064] The fitting parameters include the insertion depth of the conductive tube 2 and the extension conductive tube 6 inside the sleeve, as well as the fitting gap. The fitting gap is the maximum allowable displacement difference at the fitting point between the two.

[0065] S2: Specify the mechanical properties for each component in the geometric model to meet the accuracy requirements of displacement calculation;

[0066] Among them, the mechanical properties include at least the density, elastic modulus and Poisson's ratio of the component material, and the material properties of each component match the mechanical properties of the corresponding component of the actual bushing.

[0067] First, specify the material properties of the core components in the geometric model. Typically, capacitor core 1 is made of resin-impregnated paper, conductive tube 2 is made of copper, mounting flange 3, insulator mounting flange 5, bushing internal extension conductive tube 6, insulator end cap 7, and bushing air end terminal 8 are made of aluminum alloy, and air end hollow insulator 4 is made of glass fiber impregnated with epoxy. The main material parameters involved are density, elastic modulus, and Poisson's ratio.

[0068] S3: Apply constraints and operating loads to the geometric model that conform to the actual application scenario of the casing;

[0069] Wherein: the constraint condition is to apply a fixed constraint to the mounting flange 3 of the sleeve;

[0070] The operating load includes the gravity load applied to all components, as well as the external load applied to the air terminal 8 of the bushing. The external load corresponds to the force generated by the external connection hardware, shielding ring and wires during actual operation.

[0071] like Figure 3 As shown, first specify the installation angle of the bushing and the load of the air end terminal 8 of the bushing. Usually, the lower end face of the mounting flange 3 is fixed and constrained, and standard gravity load is applied to all components. The rated operating load is applied to the air end terminal 8 of the bushing.

[0072] The standard gravity load is vertically downward, while the operating load mainly considers the force exerted by external connecting hardware, shielding rings, wires, etc. on the air terminal 8 of the bushing. It is usually vertically downward, but can be changed according to the actual operating conditions.

[0073] S4: The displacement of each component in the geometric model is calculated using the finite element method. During the calculation, the contact relationship between the conductive tube 2 and the extended conductive tube 6 inside the sleeve is set to be irrelevant, and the contact relationship between the other components is set to be bound.

[0074] It should be noted that when using the finite element method to calculate displacement, the coupling effect of gravity load and external load is incorporated into the finite element calculation process.

[0075] The finite element method is typically used to calculate the displacement of each component.

[0076] In the calculation, the contact relationship between conductive tube 2 and the internal extension conductive tube 6 of the bushing needs to be set to be independent, while other contacts can be set to be bonded. This is because the actual connection between conductive tube 2 and insulator mounting flange 5 is through contact finger 9, which is a complex sliding contact. Detailed simulation of these contacts would require significant computational resources.

[0077] The operating state that this invention focuses on does not require simulating such a detailed process; it only needs to know the relative displacement of the components. The main task can be completed at a lower cost, which can significantly improve computational efficiency.

[0078] S5: Read the displacement calculation results and determine whether the displacement difference between the conductive tube 2 and the mating part of the extended conductive tube 6 inside the sleeve exceeds the mating parameters;

[0079] If the condition does not exceed the limit, the operating status of the bushing electrical connection is deemed qualified.

[0080] If the displacement difference exceeds the specified parameters, analyze the interference characteristics of the two components and repeat steps S1 to S5 until the displacement difference does not exceed the matching parameters.

[0081] Interference features include at least one parameter in the sleeve structure, component material, or operating load.

[0082] The specific method for determining whether the displacement difference exceeds the fit parameters is as follows:

[0083] Extract the relative displacement difference Δδ between conductive tube 2 and the extended conductive tube 6 inside the sleeve in the electrical connection area;

[0084] Compare |Δδ| with the fit clearance Δg in the fit parameters;

[0085] If |Δδ|≤Δg, then it is deemed qualified;

[0086] If |Δδ|>Δg, then it is deemed unqualified and proceeds to the interference feature analysis stage.

[0087] The specific method for interference feature analysis is as follows:

[0088] The type of interference can be distinguished based on the relative deformation trends of conductive tube 2 and the extended conductive tube 6 inside the sleeve:

[0089] If the downward deformation of conductive tube 2 is greater than the downward deformation of the extended conductive tube 6 inside the sleeve, it is an interference of the first kind.

[0090] If the downward deformation of conductive tube 2 is less than the downward deformation of the extended conductive tube 6 inside the sleeve, it is a second type of interference.

[0091] The adjustment method for different types of interference is as follows:

[0092] For the first type of interference, adjust the stiffness of the air-end hollow insulator 4;

[0093] For the second type of interference, adjust the external load of the air end terminal 8 of the bushing or the stiffness of the air end hollow insulator 4;

[0094] Stiffness adjustment is achieved by modifying the material properties or structural form of the air-end hollow insulator 4, while external load adjustment is achieved by optimizing the structure or weight of the external connection components.

[0095] Specifically, when reading the displacement calculation results, if the displacement difference between the mating parts of the conductive tube 2 and the extended conductive tube 6 inside the sleeve is large, exceeding the size of the mating gap.

[0096] In practice, it is necessary to determine whether the displacement difference between the two components, conductive tube 2 and the extended conductive tube 6 inside the sleeve, is greater than the fitting clearance. If it is not greater than the fitting clearance, the design can be considered good and no modification is needed.

[0097] If the gap is greater than the fit clearance, further analysis reveals that if the downward bending deformation of conductive tube 2 is greater than the downward deformation of the extended conductive tube 6 inside the sleeve, then conductive tube 2 and the extended conductive tube 6 inside the sleeve tend to interfere with mode 1; refer to Figure 4 The state shown.

[0098] If the downward bending deformation of conductive tube 2 is smaller than the downward deformation of the extended conductive tube 6 inside the sleeve, then conductive tube 2 and the extended conductive tube 6 inside the sleeve tend to interfere in mode 2, as shown in the reference. Figure 5 The state shown.

[0099] If interference method 1 is used, the stiffness of the air-end hollow insulator 4 can be reduced (by modifying the material or structure). If interference method 2 is used, the force on the bushing air-end terminal 8 can be reduced or the stiffness of the air-end hollow insulator 4 can be increased (by modifying the material or structure). Repeat the above processes S1 to S5.

[0100] Reference Figures 6 to 11 The following explanation uses a ±500kV converter transformer valve-side bushing as an example:

[0101] Step 1: Refer to Figure 6 , Figure 6 The established geometric model of the bushing includes capacitor core 1, conductive tube 2, mounting flange 3, air-end hollow insulator 4, insulator mounting flange 5, internal extension conductive tube of the bushing 6, insulator end cover 7, and bushing air-end terminal block 8.

[0102] According to the electrical connection and mating relationship, such as Figure 7 As shown: the outer radius of conductive tube 2 is 78mm, the inner radius of the inner extension conductive tube 6 inside the sleeve is 79mm, and the insertion depth of conductive tube 2 and the inner extension conductive tube 6 inside the sleeve are set to 1800mm and the fit tolerance is 1mm.

[0103] Step 2: Assign material properties to each component in the geometric model. Capacitor core 1 is made of resin-impregnated paper, conductive tube 2 is copper, mounting flange 3, insulator mounting flange 5, bushing internal extension conductive tube 6, insulator end cap 7, and bushing air end terminal 8 are aluminum alloy, and air end hollow insulator 4 is glass fiber impregnated with epoxy. The density, elastic modulus, and Poisson's ratio of each material are shown in the table below.

[0104] Material unit copper aluminum alloy Impregnated paper Epoxy-impregnated glass fiber density kg / m3 8900 2770 2400 2000 elastic modulus GPa 126 71 24 32 elastic modulus — 0.345 0.33 0.3 0.28

[0105] Step 3: Specify the installation angle and load of the sleeve, such as... Figure 8 As shown, the bushing installation angle is set to 60°, the lower end face of the bushing installation flange 3 is fixed and constrained, a standard gravity load is applied to all components, and a rated operating load of 2000N is applied vertically downward to the top of the bushing air end terminal 8.

[0106] Step 4: Calculate the displacement of each component, typically using the finite element method. During the calculation, the contact relationship between conductive tube 2 and the extended conductive tube 6 inside the sleeve should be set to independent, while other contact relationships should be set to bonded.

[0107] Step 5: Read the displacement calculation results and refer to... Figure 9 and Figure 10 It can be seen that the downward bending deformation of conductive tube 2 is smaller than that of the downward deformation of the extended conductive tube 6 inside the sleeve. The two tend to be interference mode 2. The vertical displacement is read. The displacement of conductive tube 2 is -2.2mm, and the displacement of the extended conductive tube 6 inside the sleeve is -4.8mm. The displacement difference of 2.6mm is greater than the fit tolerance of 1mm.

[0108] Subsequently, the tension at the terminal is reduced, for example, to 0N, and the calculation results are as follows. Figure 11As shown, the displacement of conductive tube 2 is -1.77mm, and the displacement of the extended conductive tube 6 inside the sleeve is -2.77mm. The displacement difference of 1mm is equal to the fit tolerance of 1mm.

[0109] In summary, this invention extracts only the "relative displacement difference Δδ" between the conductive tube 2 and the extended conductive tube 6 inside the sleeve in the electrical connection range, and directly compares it with the factory fitting clearance Δg: if |Δδ|≤Δg, the electrical connection is determined to be in the safe alignment range; if |Δδ|>Δg, a "structure-load" adjustment command is immediately output without simulating the actual contact state of the touch finger; the "displacement difference-fit clearance" is used as a sufficient and necessary condition for electrical connection failure, replacing the traditional temperature rise or post-incident maintenance criteria.

[0110] In addition, in the overall finite element model, the contact surface between the conductive tube 2 and the extended conductive tube 6 inside the sleeve is deliberately set to "no contact / unrelated", and all other components are bound together, thereby reducing the contact problem that originally required nonlinear sliding solution to a linear static problem; by "deliberately ignoring the nonlinearity of local contact of the finger", the "system-level relative displacement" can be solved quickly, realizing second-level iteration in the design stage.

[0111] Secondly, the "installation tilt angle θ + standard gravity g + terminal external load F" is used as a parameterizable input matrix at once, with θ ranging from 0 to 90° and F ranging from 0 to rated lead tension, covering any combination of oblique installation, high altitude, strong wind and icing that may occur on site; by incorporating "installation angle and external load" into the same calculation process, instead of only considering vertical installation or only considering gravity in the traditional way.

[0112] Finally, based on the sign of Δδ, two types of interference are automatically distinguished: Interference mode 1 (conductive tube 2 moves downward relative to each other) → outputs the suggestion to "reduce the bending stiffness of hollow insulators";

[0113] Interference method 2 (relative downward movement of the extended conductive tube 6 inside the bushing) → outputs the suggestion of "reducing the external load on the terminal or increasing the stiffness of the insulator"; and forms a closed-loop iterative interface until |Δδ|≤Δg; by establishing a one-to-one mapping table between the "displacement difference sign" and the "structure-load modification direction", automatic software optimization can be achieved.

[0114] Traditional methods require waiting until the bushing is energized before detecting poor electrical connections due to gravity-induced misalignment through infrared thermography or power-off lifting. By this time, the equipment is already at risk of overheating or even discharge, making diagnosis costly and preventing problems beforehand. This invention directly compares the relative displacement difference between the conductive tube 2 and the extended conductive tube 6 within the electrical connection area with the factory clearance. This allows for a quantitative assessment of whether the contact finger 9 maintains axial symmetry during the design phase, eliminating the need to wait for temperature rise signals or disassemble the device, thus proactively mitigating risks.

[0115] Meanwhile, existing technologies require a large amount of nonlinear computational resources to realistically simulate the sliding contact of the watch strap / spring finger in the finite element method, which is difficult to implement in engineering. This invention deliberately sets the contact between the two tubes to be "irrelevant", reducing the problem to linear static displacement calculation. It can complete the full-condition scan of 0-90° arbitrary tilt angle and 0-rated tensile force in a few minutes using an ordinary workstation, balancing accuracy and speed, so that the sleeve obtains the "electrical connection safety certificate" before leaving the factory.

[0116] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A method for evaluating the operational state of a transformer bushing electrical connection, characterized in that: The application relates to a method for judging the electric connection state of a bushing. The method comprises the following steps: establishing a geometric model containing a bushing electric connection core component, the core component at least including a conductive tube (2) for realizing electric connection and an internal extension conductive tube (6) of the bushing, and setting a matching parameter according to the electric connection matching relationship of the two; specifying mechanical properties of each component in the geometric model to meet displacement calculation accuracy requirements; applying constraint conditions and operating loads corresponding to an actual application scenario of the bushing to the geometric model; calculating the displacement of each component in the geometric model by using a finite element method, wherein the contact relationship between the conductive tube (2) and the internal extension conductive tube (6) of the bushing is set as irrelevant, and the contact relationship between the rest components is set as binding; reading the displacement calculation result, and judging whether the displacement difference of the matching part of the conductive tube (2) and the internal extension conductive tube (6) of the bushing exceeds the matching parameter; if not, determining that the electric connection operating state of the bushing is qualified; if yes, analyzing interference characteristics of the two, and repeating the above steps until the displacement difference does not exceed the matching parameter.

2. The method of claim 1, wherein: The core component of the geometric model further includes a capacitor core (1), a mounting flange (3), an air end hollow insulator (4), an insulator mounting flange (5), an insulator end cover (7) and a bushing air end wiring terminal (8), and the relative positions of the components are consistent with the assembly relationship of an actual bushing.

3. The method of claim 2, wherein: The matching parameter includes the insertion depth and the matching gap of the conductive tube (2) and the internal extension conductive tube (6) of the bushing, and the matching gap is the maximum allowable displacement difference value of the matching part of the two.

4. The method of claim 3, wherein: The mechanical properties at least include the density, the elastic modulus and the Poisson's ratio of the material of the components, and the material characteristics of each component are matched with the mechanical properties of the corresponding components of the actual bushing.

5. The method of claim 4, wherein: The constraint condition is to apply a fixed constraint to the mounting flange (3) of the bushing; The operating loads include a gravity load applied to all the components, and an external load applied to the bushing air end wiring terminal (8), the external load corresponding to the acting force generated by external connecting hardware, a shielding ring and a wire in actual operation.

6. The method of claim 5, wherein: When the displacement is calculated by using the finite element method, the coupling effect of the gravity load and the external load is introduced into the finite element calculation process.

7. The method of claim 6, wherein: The interference characteristics include at least one parameter of adjusting the structure of the bushing, the material of the components or the operating load.

8. The method of claim 7, wherein: The specific way of judging whether the displacement difference exceeds the matching parameter is as follows: extracting the relative displacement difference delta delta of the conductive tube (2) and the internal extension conductive tube (6) of the bushing in the electric connection interval; comparing |delta delta| with the matching gap delta g in the matching parameter; if |delta delta| <= delta g, the result is qualified; if |delta delta| > delta g, the result is unqualified and the interference characteristic analysis link is entered.

9. The method of claim 8, wherein: The specific way of the interference characteristic analysis is as follows: According to the relative deformation trend of the conductive tube (2) and the internal extension conductive tube (6) of the bushing, the interference type is distinguished: if the downward deformation amount of the conductive tube (2) is greater than that of the internal extension conductive tube (6) of the bushing, the interference type is the first type; if the downward deformation amount of the conductive tube (2) is less than that of the internal extension conductive tube (6) of the bushing, the interference type is the second type.

10. The method of claim 9, wherein: The adjustment way for the interference type is as follows: For the first type of interference, the stiffness of the air-end hollow insulator (4) is adjusted; For the second type of interference, the external load of the bushing air-end connection terminal (8) or the stiffness of the air-end hollow insulator (4) is adjusted; The stiffness adjustment is realized by modifying the material properties or structural form of the air-end hollow insulator (4), and the external load adjustment is realized by optimizing the structure or weight of the external connection component.

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