Parameter-free design method and system for lightweight reinforcement structure of power transformer

Abstract

This invention, in the field of power systems, discloses a parameter-free design method and system for lightweight, power transformer reinforcement rib structures. By accurately simulating the true material properties of the transformer's internal insulating oil and the pressure loads during internal arc faults, the method avoids the uncertainty and errors associated with relying solely on empirical or simple approximate calculations. Comprehensive finite element analysis of the transformer's material properties, boundary conditions, and pressure loads ensures the rib structure maintains sufficient strength and rigidity even in the event of an internal transformer fault, reducing the risk of performance and lifespan deficiencies.

Description

Technical Field

[0001] The present invention belongs to the field of power systems, and in particular relates to a parameter-free design method and system for a lightweight reinforcing rib structure of a power transformer. Background Art

[0002] Power transformers are crucial equipment in power systems, playing a critical role in power transmission and distribution. When a short circuit occurs within a power transformer, internal pressure rises dramatically. To ensure structural stability during operation, the tank is typically reinforced with ribs to enhance its deformation resistance. However, traditional rib designs present challenges such as excessive weight, low material efficiency, and high manufacturing costs. Furthermore, the increased overall weight of the tank structure can also complicate transportation and installation. Therefore, achieving lightweight rib design while maintaining structural rigidity is crucial for power transformer design. Existing rib design primarily relies on empirical or simple calculations to determine the number, size, and location of ribs. Designing ribs based solely on empirical or simple calculations can easily overlook stress and operating conditions, potentially leading to over- or under-design, making it difficult to guarantee performance and lifespan, and hindering material utilization and optimization. Summary of the Invention

[0003] The purpose of the present invention is to overcome the above-mentioned problem of insufficient performance life due to experience or simple calculation, and to provide a lightweight parameter-free design method and system for the reinforcing rib structure of a power transformer.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] In a first aspect, the present invention provides a parameter-free design method for a lightweight power transformer reinforcement structure, comprising the following steps:

[0006] Construct the geometric model of the power transformer based on the power transformer and its reinforcement structure;

[0007] Obtain the material properties of the insulating oil in the power transformer, simulate the geometric model of the power transformer based on the material properties of the insulating oil in the power transformer, and obtain the pressure load when the power transformer is internally subjected to an arc fault;

[0008] Obtaining the material properties of the power transformer, dividing the power transformer into a network, and performing finite element analysis on the power transformer based on the boundary conditions of the power transformer, the material properties and boundary conditions of the power transformer, and the obtained pressure load to obtain the stiffness of the power transformer box wall;

[0009] The stiffness of the power transformer box wall is used as a constraint to determine the objective function and calculate the shape gradient function of the power transformer reinforcement.

[0010] The power transformer reinforcement structure is adjusted according to the stiffness of the power transformer box wall and the shape gradient function of the power transformer reinforcement, and the lightweight parameter-free design of the power transformer reinforcement structure is completed.

[0011] A further improvement of the present invention is to obtain the material properties of the insulating oil in the power transformer, simulate the geometric model of the power transformer based on the material properties of the insulating oil in the power transformer, and obtain the pressure load during an arc fault in the power transformer. The specific method is as follows:

[0012] Obtain material properties of insulating oil in power transformers;

[0013] According to the geometric model of the power transformer, a geometric model of the insulating oil region in the power transformer is obtained;

[0014] Simulating the geometric model of the insulating oil area in the power transformer and meshing the geometric model of the insulating oil area in the power transformer;

[0015] The bubble motion expression is used as the boundary condition of the insulating oil region;

[0016] According to the material properties of the insulating oil in the power transformer and the boundary conditions of the insulating oil area, Realizable k - ε Turbulence models simulate fluid motion in all grids;

[0017] The pressure load inside the power transformer during an arc fault is calculated based on fluid movement.

[0018] A further improvement of the present invention is to obtain the material properties of the power transformer, mesh the power transformer, obtain the boundary conditions of the power transformer, perform finite element analysis on the power transformer based on the material properties and boundary conditions of the power transformer and the obtained pressure load, and obtain the specific method of the stiffness box wall of the power transformer as follows:

[0019] Get the material properties of power transformers;

[0020] The power transformer is divided into tetrahedral unstructured grids based on the Delaunay triangulation algorithm, and boundary conditions are set;

[0021] Based on the material properties and boundary conditions of the power transformer, as well as the obtained pressure load, the power transformer is subjected to finite element analysis according to the preset calculation time and step size to obtain the mechanical response of the power transformer box wall under the oil pressure load applied to the inner wall of the power transformer;

[0022] According to the mechanical response of the power transformer tank wall under the oil pressure load applied to the inner wall of the power transformer, the stiffness of the power transformer tank wall is obtained.

[0023] A further improvement of the present invention is that the stiffness of the power transformer box wall is used as a constraint condition to determine the objective function. The specific method for calculating the shape gradient function of the power transformer reinforcement is as follows:

[0024] Taking the stiffness of the power transformer box wall as the constraint condition, the objective function with the goal of minimizing the mass of the reinforcement is established;

[0025] The objective function is combined with the Lagrangian function to obtain the shape gradient function of the power transformer.

[0026] A further improvement of the present invention is that the power transformer reinforcement structure is adjusted according to the stiffness of the power transformer box wall and the shape gradient function of the power transformer reinforcement rib. The specific method for completing the lightweight parameter-free design of the power transformer reinforcement rib structure is as follows:

[0027] According to the stiffness of the power transformer box wall and the shape gradient function of the power transformer reinforcement rib, a velocity analysis model for the power transformer reinforcement rib structure is constructed;

[0028] The velocity analysis model is used to iterate the power transformer reinforcement structure under stiffness constraints, completing the lightweight parameter-free design of the power transformer reinforcement structure.

[0029] In a second aspect, the present invention provides a parameter-free design system for a lightweight power transformer reinforcement structure, comprising:

[0030] A model building module, used for building a geometric model of the power transformer based on the power transformer and its reinforcement structure;

[0031] A pressure load acquisition module is used to obtain the material properties of the insulating oil in the power transformer, simulate the geometric model of the power transformer based on the material properties of the insulating oil in the power transformer, and obtain the pressure load when an arc fault occurs inside the power transformer;

[0032] The stiffness acquisition module is used to obtain the material properties of the power transformer, perform meshing on the power transformer, obtain the boundary conditions of the power transformer, perform finite element analysis on the power transformer based on the material properties and boundary conditions of the power transformer and the obtained pressure load, and obtain the stiffness of the power transformer box wall;

[0033] A shape gradient function acquisition module is used to determine the objective function with the stiffness of the power transformer box wall as a constraint condition and calculate the shape gradient function of the power transformer reinforcement;

[0034] The structural design module is used to adjust the power transformer reinforcement structure according to the stiffness of the power transformer box wall and the shape gradient function of the power transformer reinforcement, and complete the lightweight parameter-free design of the power transformer reinforcement structure.

[0035] A further improvement of the present invention is that the function of the pressure load acquisition module is realized by the following method:

[0036] Obtain material properties of insulating oil in power transformers;

[0037] According to the geometric model of the power transformer, a geometric model of the insulating oil region in the power transformer is obtained;

[0038] Simulating the geometric model of the insulating oil area in the power transformer and meshing the geometric model of the insulating oil area in the power transformer;

[0039] The bubble motion expression is used as the boundary condition of the insulating oil region;

[0040] According to the material properties of the insulating oil in the power transformer and the boundary conditions of the insulating oil area, Realizable k - ε Turbulence models simulate fluid motion in all grids;

[0041] The pressure load inside the power transformer during an arc fault is calculated based on fluid movement.

[0042] A further improvement of the present invention is that the function of the stiffness acquisition module is realized by the following method:

[0043] Get material properties of power transformers;

[0044] The power transformer is divided into tetrahedral unstructured grids based on the Delaunay triangulation algorithm, and boundary conditions are set;

[0045] Based on the material properties and boundary conditions of the power transformer, as well as the obtained pressure load, the power transformer is subjected to finite element analysis according to the preset calculation time and step size to obtain the mechanical response of the transformer box wall under the oil pressure load applied to the inner wall of the transformer;

[0046] According to the mechanical response of the power transformer tank wall under the oil pressure load applied to the inner wall of the power transformer, the stiffness of the power transformer tank wall is obtained.

[0047] A further improvement of the present invention is that the function of the shape gradient function acquisition module is realized by the following method:

[0048] Taking the stiffness of the power transformer box wall as the constraint condition, the objective function with the goal of minimizing the mass of the reinforcement is established;

[0049] The objective function is combined with the Lagrangian function to obtain the shape gradient function of the power transformer.

[0050] A further improvement of the present invention is that the function of the structural design module is realized by the following method:

[0051] According to the stiffness of the power transformer box wall and the shape gradient function of the power transformer reinforcement rib, a velocity analysis model for the power transformer reinforcement rib structure is constructed;

[0052] The velocity analysis model is used to iterate the conditions of the power transformer reinforcement structure under stiffness constraints, and the lightweight parameter-free design of the power transformer reinforcement structure is completed.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] This invention accurately simulates the actual material properties of the insulating oil inside a power transformer and the pressure loads during an internal arc fault, avoiding the uncertainties and errors associated with relying solely on empirical or simple approximate calculations. Comprehensive finite element analysis of the power transformer's material properties, boundary conditions, and pressure loads ensures that the rib structure maintains good strength and rigidity even in the event of an internal transformer fault, reducing the risk of performance and lifespan deficiencies. Using the stiffness of the power transformer's casing as a constraint and minimizing rib mass as the objective function, the invention uses a shape gradient function to guide rib structural adjustments, achieving systematic optimization of the rib layout and shape. This effectively reduces unnecessary material usage and significantly reduces rib mass, material cost, and manufacturing cost while meeting strength, rigidity, and reliability requirements. This invention eliminates the need for cumbersome parametric modeling; designers only need to initially define the power transformer's geometric model and set the relevant boundary conditions and load conditions. It then automatically performs iterative optimization. The optimization process can be iterated through finite element simulation to automatically obtain the optimal topology or shape that meets the constraints. This reduces the traditional manual iteration of the "trial and error—modify—trial and error" process, significantly improving design efficiency. When dealing with power transformers of different models, sizes, or with special requirements, the present invention can rapidly adjust the design objective function and constraints through the same design process to obtain new optimization results. This design has strong adaptability and can automatically solve and optimize under various operating conditions (such as different internal fault pressures and external loads). In summary, by analyzing the actual response of power transformers under internal arc fault loads and combining it with automated topology and shape optimization, the present invention significantly improves the reliability and accuracy of the design of power transformer reinforcement ribs, reduces the risk of insufficient performance and lifespan due to experience or simple calculations, and simultaneously takes into account structural lightweighting and improved design efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a flow chart of Example 1;

[0056] Figure 2This is a system diagram of Example 2;

[0057] Figure 3 This is the geometric model diagram of the power transformer;

[0058] Figure 4a This is a schematic diagram of the power transformer reinforcement structure before optimization design;

[0059] Figure 4b This is a schematic diagram of the power transformer reinforcement structure after optimized design; DETAILED DESCRIPTION

[0060] In order to further understand the content of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the embodiments are only for explaining the present invention and are not intended to limit it.

[0061] Example 1:

[0062] See also Figure 1 , a parameter-free design method for lightweight reinforcement structure of power transformer includes the following steps:

[0063] S1, construct the geometric model of the power transformer based on the power transformer and its reinforcement structure.

[0064] S2, obtaining material properties of the insulating oil in the power transformer, simulating a geometric model of the power transformer based on the material properties of the insulating oil in the power transformer, and obtaining a pressure load when an arc fault occurs inside the power transformer.

[0065] S3, obtaining the material properties of the power transformer, meshing the power transformer, obtaining the boundary conditions of the power transformer, performing finite element analysis on the power transformer based on the material properties and boundary conditions of the power transformer and the obtained pressure load, and obtaining the stiffness of the power transformer box wall.

[0066] S4, determining the objective function with the stiffness of the power transformer box wall as a constraint condition, and calculating the shape gradient function of the power transformer reinforcement.

[0067] S5, adjusting the power transformer reinforcement structure according to the stiffness of the power transformer box wall and the shape gradient function of the power transformer reinforcement, completing the lightweight parameter-free design of the power transformer reinforcement structure.

[0068] Example 2:

[0069] See also Figure 2 , a lightweight parameter-free design system for power transformer reinforcement structure, including:

[0070] A model building module, used for building a geometric model of the power transformer based on the power transformer and its reinforcement structure;

[0071] A pressure load acquisition module is used to obtain the material properties of the insulating oil in the power transformer, simulate the geometric model of the power transformer based on the material properties of the insulating oil in the power transformer, and obtain the pressure load when an arc fault occurs inside the power transformer;

[0072] The stiffness acquisition module is used to obtain the material properties of the power transformer, perform meshing on the power transformer, obtain the boundary conditions of the power transformer, perform finite element analysis on the power transformer based on the material properties and boundary conditions of the power transformer and the obtained pressure load, and obtain the stiffness of the power transformer box wall;

[0073] A shape gradient function acquisition module is used to determine the objective function with the stiffness of the power transformer box wall as a constraint condition and calculate the shape gradient function of the power transformer reinforcement;

[0074] The structural design module is used to adjust the power transformer reinforcement structure according to the stiffness of the power transformer box wall and the shape gradient function of the power transformer reinforcement, and complete the lightweight parameter-free design of the power transformer reinforcement structure.

[0075] Example 3:

[0076] This embodiment further defines the functions of the method and model building module in S1 of the above embodiment, as follows:

[0077] The 3D model of the power transformer oil tank and reinforcement ribs was drawn using Spaceclaim software. Small components such as bolts, gaskets, and seals were simplified to save computing time and cost, resulting in a geometric model of the power transformer.

[0078] Example 4:

[0079] This embodiment further defines the method of S2 and the functions of the pressure load acquisition module in the above embodiment as follows:

[0080] The geometric model of the power transformer is imported into the ANSYS Fluent module (using the computational fluid dynamics numerical simulation module) and meshed to ensure that the mesh size meets the calculation accuracy requirements.

[0081] Select transient calculation, set the material properties of the insulating oil, and use Realizable k - ε Turbulence model simulates fluid motion, Realizable k - ε The transport equation of the turbulence model is expressed as:

[0082]

[0083]

[0084] in, and Turbulent kinetic energy and dissipation rate The corresponding turbulent Prandtl number is, is the fluid density, is the dynamic viscosity, It's speed, G k,m is the turbulent kinetic energy generation term, For time, is the Nabla operator, is a constant 4.04, is the empirical constant 0.4, is the characteristic velocity scalar, is the change in turbulent kinetic energy caused by the mean velocity gradient, is the modulus of the strain rate tensor, is the empirical constant 1.9, is the kinematic viscosity, It is derived from the following formula.

[0085]

[0086] When a short circuit occurs inside a power transformer, the insulating oil vaporizes and cracks under the action of a high-temperature, high-energy arc to form bubbles. The behavior of the bubbles is described by the following formula:

[0087]

[0088] in, R is the bubble radius, c is the distance between the bubble center and the boundary of fluid motion, is the bubble boundary acceleration, is the bubble boundary velocity, is the pressure exerted by the fluid at the bubble boundary, p c is the pressure at the fluid boundary.

[0089] The expression of bubble behavior is used as the fluid boundary condition change to simulate and calculate the pressure load when an arc fault occurs inside the power transformer.

[0090] Example 5:

[0091] This embodiment further defines the method of S3 and the functions of the stiffness acquisition module in the above embodiment, as follows:

[0092] Get material properties of power transformers;

[0093] The three-dimensional model of the power transformer oil tank and reinforcement ribs is imported into the ANSYS Fluent module. According to the material properties of the power transformer, the power transformer is divided into a tetrahedral unstructured grid based on the triangulation algorithm, and the boundary conditions are set.

[0094] According to the material properties of the power transformer and the obtained pressure load and boundary conditions, according to the preset calculation time and step size, the power transformer is subjected to finite element analysis to obtain the mechanical response of the power transformer box wall under the oil pressure load applied to the inner wall of the power transformer;

[0095] According to the mechanical response of the power transformer box wall under the oil pressure load applied to the inner wall of the power transformer, the stiffness of the power transformer is obtained.

[0096] Example 6:

[0097] This embodiment further defines the method of S4 and the functions of the shape gradient function acquisition module in the above embodiment, as follows:

[0098] Taking the stiffness of the power transformer box wall as the constraint condition, the objective function with the goal of minimizing the mass of the reinforcement is established:

[0099]

[0100] in, M T is the total volume of the reinforcement, is the total number of reinforcement ribs, j are the numbers of different reinforcement ribs. is the volume of the jth reinforcement, h is the height of the integral differential element, A j For the j The cross-sectional area of the reinforcement, is the cross-sectional area of the reinforcement, l For softness, is the bilinear mapping between structural internal force and displacement, is the in-plane displacement of the middle part of the reinforcement, is the out-of-plane displacement of the middle part of the stiffener, is the corner in the middle of the reinforcement, is the in-plane virtual displacement of the middle part of the reinforcement, is the out-of-plane virtual displacement of the middle part of the reinforcement, is the virtual corner in the middle of the reinforcement. is the flexibility constraint value.

[0101] The constraints are:

[0102]

[0103]

[0104] in, m represents the shear correction factor; q is the out-of-plane distributed force per unit area; is the in-plane load per unit area; is the out-of-plane bending moment per unit area; is the shear force per unit length; is the bending moment per unit length; is the load per unit length in the plane, is the in-plane displacement in the virtual displacement, is the out-of-plane displacement in the virtual displacement, is the rotation angle in virtual displacement, is the elastic tensor of shear stress, is the shear strain component, is the virtual shear strain component, is the elastic tensor of the film stress, is the displacement field gradient, is the gradient of the virtual displacement field, is the elastic tensor of bending stress, is the gradient of the rotation field, is the gradient of the virtual displacement rotation field, For unit area The in-plane load component in the direction, is the displacement component within the virtual displacement field, is the imaginary rotation component, For the j The area of the unit.

[0105] The Lagrangian function of the optimization problem with the goal of minimizing the rib mass is as follows:

[0106]

[0107] in, is the Lagrangian function, is the Lagrange multiplier of the flexibility constraint equation.

[0108] Compute the derivative of the Lagrangian function :

[0109]

[0110]

[0111] in, is the actual in-plane displacement of the middle part of the reinforcement, is the actual out-of-plane displacement of the middle part of the reinforcement, is the actual rotation angle in the middle of the reinforcement, is the variation of the in-plane virtual displacement of the middle part of the rib, is the variation of the out-of-plane virtual displacement of the middle part of the rib, is the variation of the virtual angle in the middle of the rib, is the shape gradient function, is the boundary ∂ A j The unit outward normal vector in the plane of is the design velocity field, is the boundary of the jth unit, is the gradient of the rotation field, is the gradient of the virtual displacement rotation field, is the gradient of the actual displacement field, is the gradient of the virtual displacement field, is the rotation component, is the out-of-plane displacement component, is the out-of-plane displacement component in the virtual displacement field.

[0112] The optimal condition of the Lagrangian function L is:

[0113]

[0114]

[0115]

[0116]

[0117]

[0118] When the optimal conditions are met, the derivative of the Lagrangian function becomes:

[0119]

[0120] in, is the load distribution function on the boundary, is the normal vector.

[0121] Export the shape gradient function:

[0122]

[0123] in, is the rotation angle of the middle part of the reinforcement about the coordinate Directional The partial derivatives of the components, is the out-of-plane displacement of the middle part of the reinforcement The gradient component of the coordinate, is the out-of-plane displacement of the middle part of the reinforcement The gradient component of the coordinate,

[0124] Example 7:

[0125] This embodiment further defines S5 in the above embodiment, specifically as follows:

[0126] According to the stiffness of the power transformer and the shape gradient function of the power transformer reinforcement, a velocity analysis model is constructed for the power transformer reinforcement structure;

[0127] Assuming a shape constraint acts on the area change, the infinitesimal change of the area can be expressed as:

[0128]

[0129] in, To make the initial area A j Point in X Mapping to update area A s j The mapping function of the points in is the iteration step length, is the mapping function after iteration.

[0130] The expression of the velocity analysis model is:

[0131]

[0132] in, For the j The in-plane velocity of each element, For the j The out-of-plane velocity of each element, For the j The corner of a unit.

[0133] The velocity analysis model is used to iterate the power transformer reinforcement structure under constraints, completing the lightweight parameter-free design of the power transformer reinforcement structure.

[0134] Assuming that the stiffener does not change in the out-of-plane direction, an additional constraint is imposed in the direction of the stiffener surface normal, namely: = 0. Design velocity field with reinforcement Based on this, the shape of the stiffener is updated and iterated until the iteration converges, and the optimal solution for the lightweight optimization design of the stiffener is obtained.

[0135] Example 8:

[0136] This embodiment performs free boundary design on the shape of the reinforcement ribs without reducing the stiffness of the transformer, thereby achieving a lightweight design of the reinforcement rib structure:

[0137] Step 1: Draw the geometric model of the power transformer, draw the 3D model of the power transformer oil tank and reinforcement, and simplify small components such as bolts, gaskets, and sealing rings. In this implementation case, the volume of the oil tank is 3 m × 4 m × 5 m. 8 rows of reinforcement ribs are evenly arranged on the front and back walls of the power transformer, and 6 rows of reinforcement ribs are evenly arranged on the left and right side walls, as shown in the figure. Figure 3 shown.

[0138] Step 2: Set the material properties of the insulating oil, which is a compressible fluid with a base density of 895 kg / m 3 , select Realizable k - ε Turbulence model simulates fluid motion and sets Realizable k - ε The parameters required in the turbulence model and the boundary conditions of the insulating oil area (such as the pressure outlet) are set as follows:

[0139] The bubble dynamics equation is used to solve the boundary motion of bubbles generated by arc vaporization of insulating oil during a fault:

[0140]

[0141] The oil pressure is obtained by solving the flow field using the bubble dynamics equation. The boundary motion of the bubble affects the changes in the flow field, which in turn affects the expansion and contraction of the bubble. The flow field is solved using the finite volume method, with a calculation time of 80 ms and a calculation step size of 0.1 ms. The oil pressure acting on each wall of the power transformer is obtained and used as the boundary condition of the insulating oil region.

[0142] Step 3: Import the geometric model of the power transformer into the ANSYS Fluent module and mesh the fluid part inside the power transformer with a mesh size of 0.1 m. Check that the mesh quality meets the requirements. Set the material properties of the power transformer body and reinforcement, divide the solid domain network, and set the material of the power transformer body and reinforcement to structural steel with a density of 7850 kg / m 3 , Young's modulus 2.1×10 11 Pa, Poisson's ratio 0.3, and yield strength 339 MPa. A mesh size of 0.1 m was created. The bottom of the power transformer was fixed, and a pressure load was applied internally. A finite element solution was performed with a calculation time of 80 ms and a step size of 0.1 ms to determine the stiffness of the power transformer wall.

[0143] Step 4: Establish an optimization problem with the goal of minimizing the mass of the reinforcement ribs. The stiffness of the power transformer box wall is used as the constraint condition of the optimization problem. The objective function of the optimization problem is as follows:

[0144]

[0145] The Lagrangian function of the optimization problem with the goal of minimizing the rib mass is as follows:

[0146]

[0147] Compute the derivative of the Lagrangian function:

[0148]

[0149] The optimal condition of the Lagrangian function L is:

[0150]

[0151]

[0152]

[0153]

[0154]

[0155] When the optimal conditions are met, the derivative of the Lagrangian function becomes:

[0156]

[0157] The shape gradient function of the stiffener structure is derived:

[0158]

[0159] Step 5: Perform velocity analysis, iterate the rib shape, perform velocity analysis based on the finite element calculation results and the shape gradient function, and solve the design speed from the control equation of the design speed:

[0160]

[0161] Assuming that the stiffener does not change in the out-of-plane direction, an additional constraint is imposed in the direction of the stiffener surface normal, namely: = 0. Design velocity field with reinforcement V j Based on this, the shape of the reinforcement is updated and iterated until the iteration converges, completing the parameter-free lightweight design of the power transformer reinforcement structure.

[0162] The final optimized shape of the reinforcement is as follows Figure 4a and Figure 4b As shown, the volume of the reinforcement before optimization is 0.12 m 3 , the optimized volume is 0.10 m 3, a 17% reduction; the maximum deformation of the fuel tank wall was 24.7 mm before optimization and 24.5 mm after optimization, without compromising the tank's deformation resistance. This paper combines parameter-free shape optimization technology with finite element simulation analysis to optimize the power transformer reinforcement structure, achieving a lightweight design of the transformer reinforcement and providing a reliable optimization strategy for engineering practice.

[0163] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A parameter-free design method for lightweight reinforcement structure of power transformer, characterized in that: The following steps are involved: Construct the geometric model of the power transformer based on the power transformer and its reinforcement structure; Obtain the material properties of the insulating oil in the power transformer, simulate the geometric model of the power transformer based on the material properties of the insulating oil in the power transformer, and obtain the pressure load when the power transformer is internally subjected to an arc fault; Obtaining material properties of the power transformer, meshing the power transformer, obtaining boundary conditions of the power transformer, performing finite element analysis on the power transformer based on the material properties and boundary conditions of the power transformer and the obtained pressure load, and obtaining the stiffness of the power transformer box wall; The stiffness of the power transformer box wall is used as a constraint to determine the objective function and calculate the shape gradient function of the power transformer reinforcement. The power transformer reinforcement structure is adjusted according to the stiffness of the power transformer box wall and the shape gradient function of the power transformer reinforcement, and the lightweight parameter-free design of the power transformer reinforcement structure is completed.

2. The parameter-free design method for lightweight power transformer reinforcement structure according to claim 1 is characterized in that: The specific method for obtaining the material properties of the insulating oil in the power transformer and simulating the geometric model of the power transformer based on the material properties of the insulating oil in the power transformer to obtain the pressure load during an arc fault inside the power transformer is as follows: Obtain material properties of insulating oil in power transformers; According to the geometric model of the power transformer, a geometric model of the insulating oil region in the power transformer is obtained; Simulating the geometric model of the insulating oil area in the power transformer and meshing the geometric model of the insulating oil area in the power transformer; The bubble motion expression is used as the boundary condition of the insulating oil region; According to the material properties of the insulating oil in the power transformer and the boundary conditions of the insulating oil area, Realizable k - ε Turbulence models simulate fluid motion in all grids; The pressure load inside the power transformer during an arc fault is calculated based on fluid movement.

3. The parameter-free design method for lightweight power transformer reinforcement structure according to claim 1 is characterized in that: The specific method for obtaining the material properties of the power transformer, meshing the power transformer, obtaining the boundary conditions of the power transformer, and performing finite element analysis on the power transformer based on the material properties and boundary conditions of the power transformer and the obtained pressure load to obtain the stiffness of the power transformer box wall is as follows: Get the material properties of power transformers; The power transformer is divided into tetrahedral unstructured grids based on the Delaunay triangulation algorithm, and boundary conditions are set; Based on the material properties and boundary conditions of the power transformer, as well as the obtained pressure load, the power transformer is subjected to finite element analysis according to the preset calculation time and step size to obtain the mechanical response of the power transformer box wall under the oil pressure load applied to the inner wall of the power transformer; According to the mechanical response of the power transformer tank wall under the oil pressure load applied to the inner wall of the power transformer, the stiffness of the power transformer tank wall is obtained.

4. The parameter-free design method for lightweight power transformer reinforcement structure according to claim 1 is characterized in that: The objective function is determined with the stiffness of the power transformer box wall as the constraint condition. The specific method for calculating the shape gradient function of the power transformer reinforcement is as follows: Taking the stiffness of the power transformer box wall as the constraint condition, the objective function with the goal of minimizing the mass of the reinforcement is established; The objective function is combined with the Lagrangian function to obtain the shape gradient function of the power transformer.

5. The parameter-free design method for lightweight power transformer reinforcement structure according to claim 1 is characterized in that: The specific method for adjusting the power transformer reinforcement structure according to the stiffness of the power transformer box wall and the shape gradient function of the power transformer reinforcement ribs and completing the lightweight parameter-free design of the power transformer reinforcement rib structure is as follows: According to the stiffness of the power transformer box wall and the shape gradient function of the power transformer reinforcement rib, a velocity analysis model for the power transformer reinforcement rib structure is constructed; The velocity analysis model is used to iterate the power transformer reinforcement structure under constraints, completing the lightweight parameter-free design of the power transformer reinforcement structure.

6. A parameter-free design system for lightweight reinforcement structure of power transformers, characterized by: include: A model building module, used for building a geometric model of the power transformer based on the power transformer and its reinforcement structure; A pressure load acquisition module is used to obtain the material properties of the insulating oil in the power transformer, simulate the geometric model of the power transformer based on the material properties of the insulating oil in the power transformer, and obtain the pressure load when an arc fault occurs inside the power transformer; The stiffness acquisition module is used to obtain the material properties of the power transformer, perform meshing on the power transformer, obtain the boundary conditions of the power transformer, perform finite element analysis on the power transformer based on the material properties and boundary conditions of the power transformer and the obtained pressure load, and obtain the stiffness of the power transformer box wall; A shape gradient function acquisition module is used to determine the objective function with the stiffness of the power transformer box wall as a constraint condition and calculate the shape gradient function of the power transformer reinforcement; The structural design module is used to adjust the power transformer reinforcement structure according to the stiffness of the power transformer box wall and the shape gradient function of the power transformer reinforcement, and complete the lightweight parameter-free design of the power transformer reinforcement structure.

7. The parameter-free design system for lightweight power transformer reinforcement structure according to claim 6 is characterized in that: The functions of the pressure load acquisition module are realized through the following methods: Obtain material properties of insulating oil in power transformers; According to the geometric model of the power transformer, a geometric model of the insulating oil region in the power transformer is obtained; Simulating the geometric model of the insulating oil area in the power transformer and meshing the geometric model of the insulating oil area in the power transformer; The bubble motion expression is used as the boundary condition of the insulating oil region; According to the material properties of the insulating oil in the power transformer and the boundary conditions of the insulating oil area, Realizable k - ε Turbulence models simulate fluid motion in all grids; The pressure load inside the power transformer during an arc fault is calculated based on fluid movement.

8. The parameter-free design system for lightweight power transformer reinforcement structure according to claim 6 is characterized in that: The functions of the stiffness acquisition module are realized through the following methods: Get the material properties of power transformers; The power transformer is divided into tetrahedral unstructured grids based on the Delaunay triangulation algorithm, and boundary conditions are set; Based on the material properties and boundary conditions of the power transformer, as well as the obtained pressure load, the power transformer is subjected to finite element analysis according to the preset calculation time and step size to obtain the mechanical response of the transformer box wall under the oil pressure load applied to the inner wall of the transformer; According to the mechanical response of the power transformer tank wall under the oil pressure load applied to the inner wall of the power transformer, the stiffness of the power transformer tank wall is obtained.

9. The parameter-free design system for lightweight power transformer reinforcement structure according to claim 6, characterized in that: The functions of the shape gradient function acquisition module are implemented through the following methods: Taking the stiffness of the power transformer box wall as the constraint condition, the objective function with the goal of minimizing the mass of the reinforcement is established; The objective function is combined with the Lagrangian function to obtain the shape gradient function of the power transformer.

10. The parameter-free design system for lightweight power transformer reinforcement structure according to claim 6, characterized in that: The functions of the structural design module are realized through the following methods: According to the stiffness of the power transformer box wall and the shape gradient function of the power transformer reinforcement rib, a velocity analysis model for the power transformer reinforcement rib structure is constructed; The velocity analysis model is used to iterate the power transformer reinforcement structure under stiffness constraints, completing the lightweight parameter-free design of the power transformer reinforcement structure.

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