A method and device for optimizing a transformer tank shell reinforcement structure

Abstract

The application provides an optimization method and device for a transformer oil tank shell reinforcing structure, constructs a structure state space based on a structure state vector; divides the structure state space into multiple progressive levels and determines a starting progressive level; generates a candidate structure state sequence in the starting progressive level and performs static force analysis to obtain a mechanical performance result; updates a current optimal state; executes a next progressive level after the starting progressive level is traversed; and outputs the current optimal state, reinforcing structure parameters corresponding to the current optimal state and the mechanical performance result after all the progressive levels are traversed. The mass increment and performance improvement of each candidate structure state can be directly compared through static force analysis, thereby establishing a quantitative mapping relationship between the mass and performance of the reinforcing rib and the reinforcing arch in terms of external pressure stability, and providing a decision basis for scheme optimization; the progressive level division simultaneously restricts the search direction, avoids unordered traversal of the whole space, and significantly reduces the calculation cost.

Description

Technical Field

[0001] This application relates to the field of power equipment structural optimization design technology, and in particular to an optimization method and device for strengthening the structure of a transformer tank shell. Background Technology

[0002] Before leaving the factory, oil-immersed transformers must undergo vacuum drying and vacuum oil filling processes to remove moisture and gases from the insulation materials. According to industry specifications, the residual pressure inside the tank during the drying stage must not exceed 133 Pa, and oil filling is also carried out under vacuum. At this time, the outside of the tank is at atmospheric pressure, while the inside is approximately a vacuum, subjecting the casing to significant external pressure loads. If the reinforcement structure is not properly designed, the panels may experience plastic buckling or even weld cracking, threatening sealing and operational safety.

[0003] Currently, shell reinforcement structures often employ optimization methods based on intelligent algorithms, such as topology optimization, genetic algorithms, or particle swarm optimization, using parametric modeling and batch finite element simulations for optimization. However, when these methods are directly applied to optimize the vacuum strength of transformer tanks, a core flaw exists: the failure to establish a quantitative mapping relationship between the mass and efficiency of the reinforcing ribs and the reinforcing arches in terms of external pressure stability makes it impossible to determine the efficiency of increasing rib height, increasing rib thickness, or replacing ribs with arches in improving the critical instability pressure under the same mass increment. This leads to disordered expansion of the search space and high computational costs. Summary of the Invention

[0004] In view of the shortcomings of the prior art, this application provides an optimization method and apparatus for the reinforcing structure of transformer tank shell to solve the problem of high computational cost.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] The first aspect of this application provides an optimized method for reinforcing the structure of a transformer tank housing, including:

[0007] The structural state space is constructed based on the structural state vector; the structural state vector includes at least vertical strengthening structural parameters and horizontal strengthening structural parameters;

[0008] The structural state space is divided into multiple progressive levels; the progressive levels include a base layer, a vertical reinforcement layer, or a horizontal reinforcement layer;

[0009] The starting progressive level is determined from the multiple progressive levels based on the transformer enclosure panel;

[0010] Within the initial progressive level, a sequence of candidate structural states is generated according to the progressive rules;

[0011] A static analysis is performed on the current candidate structural state in the candidate structural state sequence to obtain mechanical performance results; the mechanical performance results include structural mass, maximum deformation, and maximum equivalent stress.

[0012] The current optimal state is updated based on the mechanical performance results and the current candidate structure state.

[0013] After the candidate structure state sequence within the initial progressive level has been traversed, the next progressive level of the initial progressive level is selected from all progressive levels. The next progressive level is then used as the initial progressive level. The process then returns to the initial progressive level to generate the candidate structure state sequence according to the progressive rules, until all progressive levels have been traversed.

[0014] After all progressive levels have been traversed, the current optimal state and the corresponding reinforced structural parameters and mechanical performance results are output.

[0015] Optionally, determining the starting progressive level from the plurality of progressive levels based on the transformer housing panel includes:

[0016] When the transformer housing panel is a long axis side panel, the vertical reinforcing layer is determined as the starting progressive layer;

[0017] When the transformer housing panel is a short-axis side panel, the reference layer is determined as the starting progressive layer.

[0018] Optionally, dividing the structural state space into multiple progressive levels includes:

[0019] The unreinforced structural states in the structural state space are divided into the reference layer;

[0020] All states containing vertically reinforcing structures in the structural state space are divided into vertically reinforcing layers; the vertically reinforcing structure includes vertical reinforcing ribs and vertically reinforcing arches;

[0021] All states in the structural state space that have added transverse reinforcement on the basis of vertical reinforcement are classified as transverse reinforcement layers; the transverse reinforcement structure includes transverse reinforcing ribs and transverse reinforcing arches.

[0022] Optionally, generating a candidate structure state sequence according to a progressive rule within the initial progressive level includes:

[0023] If the starting progressive level is the reference level, it is checked whether the starting progressive level meets the allowable constraints; the allowable constraints are that the maximum deformation is not greater than the allowable deformation and the maximum equivalent stress is not greater than the allowable equivalent stress.

[0024] If the starting progressive level does not satisfy the allowable constraint, then the next progressive level of the starting progressive level is selected from all progressive levels, and the next progressive level is used as the starting progressive level.

[0025] Within the initial progressive level, the number of reinforcement structures is increased in an incremental manner, and the first configuration state after the increase is stored as a candidate structure state in the candidate structure state sequence.

[0026] When increasing the number of reinforcing structures cannot meet the constraints, the structure is incremented according to the geometric dimensions. The second configuration state after the increment is stored as a candidate structure state in the candidate structure state sequence. The geometric dimensions include height and thickness. The constraints are that the maximum equivalent stress of the candidate structure state does not exceed the allowable equivalent stress, and the maximum deformation does not exceed the allowable deformation.

[0027] When increasing the geometric dimensions still cannot meet the constraints, the stiffeners are replaced with stiffening arches in order from the middle position to the edge position, and the replaced configuration state is stored as a candidate structural state in the candidate structural state sequence.

[0028] If the constraint condition still cannot be met after all the reinforcing structures have been replaced with the reinforcing arch, the next progressive level of the initial progressive level is triggered to increase.

[0029] During the generation of candidate structure states, if the path of the vertical or horizontal reinforcing structure intersects with the exit end, the corresponding reinforcing structure is truncated into independent segments at the exit end position, and the segmented reinforcing structures are stored as candidate structure states in the candidate structure state sequence.

[0030] Optionally, the step of performing static analysis on the candidate structural states in the candidate structural state sequence to obtain mechanical performance results includes:

[0031] A parametric geometric model is established using a finite element analysis solver, and the material properties of the parametric geometric model are defined.

[0032] Add fixed support boundary constraints and uniformly distributed external pressure loads to the defined parametric geometric model;

[0033] Based on the added parametric geometric model, static structural analysis of the candidate structural states in the candidate structural state sequence is performed to obtain the maximum deformation and the maximum equivalent stress.

[0034] The structural mass is calculated based on the reinforced structural geometry and steel density corresponding to the candidate structural states.

[0035] Optionally, updating the current optimal state based on the mechanical performance results and the candidate structural states includes:

[0036] Determine whether the maximum deformation and the maximum equivalent stress satisfy the allowable constraints;

[0037] If the maximum deformation and the maximum equivalent stress do not meet the allowable constraints, then the next candidate structural state of the current candidate structural state is taken as the current candidate structural state, and the process returns to the step of performing static analysis on the current candidate structural state in the candidate structural state sequence to obtain the mechanical performance results.

[0038] If the maximum deformation and the maximum equivalent stress satisfy the allowable constraints, then check whether there is a saved current optimal state;

[0039] If the saved current optimal state exists, then the structural quality of the current optimal state is compared with the structural quality of the current candidate structural state.

[0040] If the structural quality of the current candidate structural state is less than the structural quality of the current optimal state, then the current candidate structural state is updated to the current optimal state;

[0041] If the structural quality of the current candidate structural state is consistent with the structural quality of the current optimal state, then the structural cost-effectiveness index of the current candidate structural state is calculated based on the mechanical performance results.

[0042] Compare the structural cost-effectiveness index with the structural cost-effectiveness index of the current optimal state;

[0043] If the structural cost-effectiveness index is greater than the structural cost-effectiveness index of the current optimal state, then the candidate structural state is updated to the current optimal state.

[0044] Optional, also includes:

[0045] If the structural quality of the current candidate structural state is greater than the structural quality of the current optimal state, then the current candidate structural state is recorded as an alternative scheme, and the current optimal state is not updated.

[0046] Optional, also includes:

[0047] If k consecutive candidate structural states do not satisfy the allowable constraints within the initial progressive level, then the next progressive level of the initial progressive level is selected from all progressive levels. After the next progressive level is used as the initial progressive level, the process returns to the initial progressive level and generates a sequence of candidate structural states according to the progressive rules, until all progressive levels have been traversed.

[0048] The second aspect of this application provides an optimized device for reinforcing the transformer tank housing, comprising:

[0049] A construction unit is used to construct a structural state space based on a structural state vector; the structural state vector includes at least vertical strengthening structural parameters and horizontal strengthening structural parameters.

[0050] A partitioning unit is used to divide the structural state space into multiple progressive levels; the progressive levels include a base layer, a vertical reinforcement layer, or a horizontal reinforcement layer;

[0051] A determining unit is configured to determine the starting progressive level from a plurality of progressive levels based on the transformer housing panel;

[0052] The generation unit is used to generate a sequence of candidate structural states according to the progression rules within the initial progressive level;

[0053] The analysis unit is used to perform static analysis on the current candidate structural state in the candidate structural state sequence to obtain mechanical performance results; the mechanical performance results include structural mass, maximum deformation, and maximum equivalent stress.

[0054] The update unit is used to update the current optimal state based on the mechanical performance results and the current candidate structure state;

[0055] The feedback unit is used to filter out the next progressive level from all progressive levels after the candidate structure state sequence in the starting progressive level has been traversed, and then return to the execution generation unit after the next progressive level is used as the starting progressive level, until all progressive levels have been traversed.

[0056] The output unit is used to output the current optimal state and the corresponding reinforcement structure parameters and mechanical performance results after all progressive levels have been traversed.

[0057] Optionally, the determining unit is specifically used for:

[0058] When the transformer housing panel is a long axis side panel, the vertical reinforcing layer is determined as the starting progressive layer;

[0059] When the transformer housing panel is a short-axis side panel, the reference layer is determined as the starting progressive layer.

[0060] This application provides an optimization method and apparatus for the reinforced structure of a transformer tank shell. The method constructs a structural state space based on a structural state vector; divides the structural state space into multiple progressive levels and determines the initial progressive level; generates a sequence of candidate structural states within the initial progressive level and performs static analysis to obtain mechanical performance results; updates the current optimal state; after traversing the initial progressive level, executes the next progressive level; after traversing all progressive levels, outputs the current optimal state and the corresponding reinforced structural parameters and mechanical performance results. The mass increment and efficiency improvement of each candidate structural state can be directly compared through static analysis, thereby establishing a quantitative mapping relationship between the mass and efficiency of the reinforcing ribs and arches in terms of external pressure stability, providing a decision-making basis for selecting the optimal scheme; the progressive hierarchical division also constrains the search direction, avoiding disordered traversal of the entire space and significantly reducing computational costs. Attached Figure Description

[0061] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0062] Figure 1 A flowchart illustrating an optimization method for a transformer tank housing reinforcement structure provided in this application embodiment;

[0063] Figure 2 An optimized fuel tank modeling diagram provided in an embodiment of this application;

[0064] Figure 3 An optimized deformation cloud map provided in an embodiment of this application;

[0065] Figure 4 An optimized stress cloud diagram provided for an embodiment of this application;

[0066] Figure 5 This is a schematic diagram of the architecture of an optimized device for reinforcing the transformer tank shell, provided in an embodiment of this application. Detailed Implementation

[0067] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0068] In this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0069] like Figure 1 As shown in the flowchart, this application provides an optimization method for the reinforcing structure of a transformer tank housing, which specifically includes the following steps:

[0070] S101: Construct the structural state space based on the structural state vector.

[0071] The structural state vector includes at least vertical and horizontal reinforcement parameters, which are used to characterize the number, size, and shape of the reinforcement structures, providing a parameterized basis for subsequent progressive searches.

[0072] Optional, the vertical reinforcement structure parameters include: the number of vertical reinforcement structures. The value ranges from {0, 1, 2, 3, 4...}; the thickness of the vertical reinforcement structure. The value ranges from {10, 16, 20...}, and the unit is mm; Vertical reinforcement structure morphology marker vector. =[ , ,..., ],in ,i∈{0,1}, where 0 represents a reinforcing rib and 1 represents a reinforcing arch.

[0073] The parameters for lateral strengthening structures include: the number of lateral strengthening structures. The value ranges from {0, 1, 2...}; the thickness of the transverse reinforcement structure. The value ranges from {10, 16, 20...}, and the unit is mm; Lateral reinforcement structural morphology marker vector. =[ , ,..., , ],in j∈{0,1}; 0 represents a reinforcing rib, 1 represents a reinforced arch; geometric parameters of the arch structure, including the arch width. The value is {90, 110...}, and the unit is mm, representing the arch height. The values ​​are {50, 60, 80...}, and the units are mm and arch thickness. The value ranges from {10, 16, 20...}, and the unit is mm.

[0074] It should be noted that the above parameter values ​​are all preset default values, and can be customized and adjusted according to the tank size and vacuum strength requirements in actual applications.

[0075] S102: Divide the structural state space into multiple progressive levels.

[0076] The progressive layers include a base layer, a vertical reinforcement layer, or a horizontal reinforcement layer.

[0077] Understandably, by dividing the structural state space into ordered progressive levels according to the complexity of the enhanced structure, the complex hybrid selection problem can be decomposed into several manageable sub-problems, reducing the complexity of the optimization search.

[0078] Optionally, in another embodiment of this application, the specific implementation of step S103 includes processes A1 to A3.

[0079] A1: Divide the unreinforced structural states in the structural state space into a reference layer.

[0080] Among them, the baseline layer L0 contains only a single state s0, and the state vector =[0,0, ,0,0, [,0,0,0], where each component represents the number of vertical reinforcing structures in sequence. =0, Vertical reinforcement structure thickness =0, Vertical shape marker vector = Quantity of transverse reinforcement structures and arch width =0, Arch height =0 and arch thickness =0, meaning no reinforced structure.

[0081] A2: All states in the structural state space that contain vertically reinforced structures are divided into vertically reinforced layers; the vertically reinforced structures include vertically reinforcing ribs and vertically reinforcing arches.

[0082] The vertical reinforcement layer Lv includes all vertical reinforcement structures with different quantities, thicknesses, and shapes. The shapes include two types: reinforcing ribs and reinforcing arches. All types of vertical reinforcement structures are evenly distributed along the height direction of the shell panel.

[0083] A3: All states in the structural state space that have added horizontal reinforcement on the basis of vertical reinforcement are classified as horizontal reinforcement layers.

[0084] The transverse reinforcement structure includes transverse reinforcing ribs and transverse reinforcing arches.

[0085] It is understandable that the transverse reinforcement layer Lh includes all states of adding transverse reinforcement structures on the basis of vertical reinforcement. The transverse reinforcement structures include two types: transverse reinforcing ribs and transverse reinforcing arches, which are evenly distributed along the short axis of the shell panel.

[0086] It should be noted that the division is based on the long axis and short axis of the transformer box panel: for the long axis side panel, the vertical reinforcement layer is entered first; for the short axis side panel, the reference layer is entered first for finite element verification in the unreinforced structural state.

[0087] S103: Determine the starting progressive level from multiple progressive levels based on the transformer enclosure panel.

[0088] Since the long-axis side panel and the short-axis side panel have different stress characteristics and dimensions, different starting progressive levels need to be selected according to the panel type to adapt to the optimization requirements of each panel.

[0089] Optionally, in another embodiment of this application, the specific implementation of step S103 includes processes B1 to B2.

[0090] B1: When the transformer enclosure panel is a long axis side panel, the vertical reinforcement layer is determined as the starting progressive layer.

[0091] B2: When the transformer enclosure panel is a short-axis side panel, the reference layer is determined as the starting progressive layer.

[0092] Understandably, for short-axis side panels, if the allowable equivalent stress and allowable deformation constraints are met in the unreinforced state of the baseline layer, the unreinforced state is maintained and the current panel optimization is terminated; otherwise, the optimization proceeds to the transverse reinforcement layer. For long-axis side panels, due to their larger size, the optimization directly proceeds to the vertical reinforcement layer.

[0093] S104: Within the initial progressive level, generate a sequence of candidate structural states according to the progressive rules.

[0094] Among them, the progressive rule is used to generate candidate structure states sequentially by increasing the gradient in quality within the current level, ensuring that the search process proceeds in an orderly manner and avoiding the omission of feasible enhancement configuration schemes.

[0095] Optionally, in another embodiment of this application, the specific implementation of step S104 includes processes C1 to C7.

[0096] C1: If the starting progressive level is the base level, check whether the starting progressive level satisfies the allowable constraints.

[0097] If the initial progressive level does not satisfy the allowable constraints, then process C2 is executed.

[0098] The allowable constraints are that the maximum deformation is not greater than the allowable deformation and the maximum equivalent stress is not greater than the allowable equivalent stress.

[0099] Specifically, the process for detecting whether the initial progressive level meets the allowable constraints is as follows: Perform static analysis on the initial progressive level to obtain the structural mass, maximum deformation, and maximum equivalent stress of the reference layer; check whether the maximum deformation is not greater than the allowable deformation and whether the maximum equivalent stress is not greater than the allowable equivalent stress; if the maximum deformation is greater than the allowable deformation and / or the maximum equivalent stress is greater than the allowable equivalent stress, then execute process C2; if the maximum deformation is not greater than the allowable deformation and the maximum equivalent stress is not greater than the allowable equivalent stress, then terminate the current panel optimization.

[0100] C2: Select the next progressive level from all progressive levels and use the next progressive level as the starting progressive level.

[0101] Specifically, the next progressive level after the starting progressive level is selected from all progressive levels as the horizontal reinforcement layer.

[0102] C3: Within the initial progressive level, increment the number of strengthening structures in an incremental manner, and store the first configuration state after increment as a candidate structure state in the candidate structure state sequence.

[0103] The initial progressive layer is either a vertical reinforcement layer or a horizontal reinforcement layer.

[0104] Optionally, let the current progressive level be... , respectively corresponding to the reference layer Vertical reinforcement layer and transverse reinforcement layer Structural state vector .

[0105] Specifically, within the vertical reinforcement layer, the number of vertical reinforcement structures increases in an arithmetic progression: ,in For the initial quantity, This is the quantity step size (usually 1). The maximum number allowed to be arranged on the side wall is determined by the width within the wall. and minimum spacing Constraints determined: .

[0106] Specifically, within the transverse reinforcement layer, the number of transverse reinforcement structures increases in an arithmetic sequence.

[0107] C4: When increasing the number of reinforcing structures cannot meet the constraints, increment the structure according to the geometric dimension and store the second configuration state after increment as a candidate structure state in the candidate structure state sequence.

[0108] The geometric dimensions include height and thickness. Within a vertically reinforced layer, height has a higher priority than thickness, while within a horizontally reinforced layer, thickness has a higher priority than height. The constraint condition is that the maximum equivalent stress of the candidate structural state does not exceed the allowable equivalent stress, and the maximum deformation does not exceed the allowable deformation.

[0109] Specifically, when increasing the quantity cannot satisfy the constraints, the geometric dimensions of the i-th reinforcing structure are increased in order of priority: , Priorities are determined by cost-effectiveness gradient. η determines which dimension will have the greatest increase in stiffness per unit mass increment: , .in, For bending stiffness, To increase the cross-sectional area of ​​the structure, when > When the height is high, prioritize increasing the height; otherwise, prioritize increasing the thickness.

[0110] C5: When increasing the geometric dimensions still cannot meet the constraints, replace the stiffeners with stiffening arches in order from the middle position to the edge position, and store the replaced configuration state as a candidate structural state in the candidate structural state sequence.

[0111] C6: When the constraint conditions still cannot be met after all the reinforced structures have been replaced with reinforced arches, the next progressive level of the initial progressive level is triggered to increase.

[0112] If the initial progressive level is a vertical reinforcement layer, the next progressive level is a horizontal reinforcement layer; if the initial progressive level is a base layer or a horizontal reinforcement layer, the next progressive level is a vertical reinforcement layer.

[0113] It should be noted that for vertical reinforcement layers, the form of the reinforcing ribs is preferred, arranged in an increasing order of quantity. When increasing the number of reinforcing ribs cannot meet the allowable equivalent stress and allowable deformation constraints, the height of the reinforcing ribs is increased first, followed by the thickness. When increasing the size still cannot meet the constraints, the reinforcing ribs in the middle position are replaced with reinforcing arches, while the edge reinforcing ribs are retained. When partial replacement still cannot meet the constraints, all vertical reinforcing ribs are replaced with vertical reinforcing arches, with the arch width increased first, followed by the arch height, and finally the arch thickness. For horizontal reinforcement layers, when the vertical reinforcement layer cannot meet the constraints, one horizontal reinforcing rib is added first. When one is insufficient, two are added. When increasing the quantity and size still cannot meet the constraints, all horizontal reinforcing ribs are replaced with horizontal reinforcing arches.

[0114] C7: During the generation of candidate structure states, if the path of the vertical or horizontal reinforcing structure intersects with the exit end, the corresponding reinforcing structure is truncated into independent segments at the exit end position, and the segmented reinforcing structure is stored as a candidate structure state in the candidate structure state sequence.

[0115] Specifically, for sidewalls with outgoing wire ends, when the vertical reinforcing structure is arranged along the height direction of the sidewall, if its path intersects with the outgoing wire end, it will be automatically cut off at the location of the hole, forming an independent rib segment above the hole and an independent rib segment below the hole; when the horizontal reinforcing structure is arranged along the width direction of the sidewall, if its path intersects with the outgoing wire end or the vertical reinforcing arch, it will automatically avoid and segment, and the segment gap will be determined by a preset avoidance distance.

[0116] It should be emphasized that the above-mentioned segmented strategy at the outgoing line end ensures that the reinforced structure does not cross the opening area, thus guaranteeing the manufacturability and vacuum strength reliability of the optimized solution.

[0117] It should be noted that the candidate structural state sequences generated according to processes C1 to C7 are as follows: The candidate structural states all satisfy the manufacturability constraint and the segmentation constraint at the outgoing line end.

[0118] S105: Perform static analysis on the current candidate structural state in the candidate structural state sequence to obtain the mechanical performance results.

[0119] The mechanical performance results include structural mass, maximum deformation, and maximum equivalent stress.

[0120] Specifically, the mechanical properties of each candidate structural state are calculated by calling finite element analysis (i.e., static structural analysis of a single shell sidewall), and the maximum deformation and maximum equivalent stress are used as constraint criteria to avoid approximation errors of the surrogate model and ensure the engineering reliability of the optimization results.

[0121] Optionally, in another embodiment of this application, the specific implementation of step S105 includes processes D1 to D4.

[0122] D1: Establish a parametric geometric model using the finite element analysis solver and define the material properties of the parametric geometric model.

[0123] The finite element analysis solver can be the ANSYS solver.

[0124] Specifically, PyANSYS is invoked to start the ANSYS solver, a parametric sidewall geometry model is established, the material properties are defined as Q235B steel or Q355 steel, and the mesh size is 40mm.

[0125] D2: Add fixed support boundary constraints and uniformly distributed external pressure loads to the defined parametric geometric model.

[0126] Specifically, a fixed support boundary constraint is applied to the bottom of the box, and a uniformly distributed pressure load of 0.1 MPa is applied to the four side walls and the top of the box.

[0127] D3: Based on the added parametric geometric model, perform static structural analysis on the candidate structural states in the candidate structural state sequence to obtain the maximum deformation and maximum equivalent stress.

[0128] Among them, after performing static structural analysis, the maximum deformation and the maximum equivalent stress are extracted.

[0129] D4: Calculate the structural mass based on the geometric dimensions of the reinforced structure and the steel density corresponding to the candidate structural state.

[0130] Specifically, the structural mass is calculated from the reinforced structural geometry and steel density, and its specific manifestation is as follows: ,in, For the first A vertical reinforcing structure, Let j be the volumes of the transversely reinforced structures. For structural quality, For the density of steel, a value can be taken as follows: .

[0131] S106: Update the current optimal state based on the mechanical performance results and the current candidate structure state.

[0132] In this process, the current optimal state is gradually screened and updated through constraint judgment, quality comparison and structural cost-effectiveness index comparison, so as to ensure that the structural lightweighting is achieved while meeting the vacuum strength requirements.

[0133] Optionally, in another embodiment of this application, the specific implementation of step S106 includes processes E1 to E8.

[0134] E1: Determine whether the maximum deformation and maximum equivalent stress meet the allowable constraints.

[0135] If the maximum deformation and the maximum equivalent stress do not meet the allowable constraints, then process E2 is executed; if the maximum deformation and the maximum equivalent stress meet the allowable constraints, then process E3 is executed.

[0136] The allowable constraints are that the maximum deformation is not greater than the allowable deformation and the maximum equivalent stress is not greater than the allowable equivalent stress.

[0137] E2: Take the next candidate structure state of the current candidate structure state as the current candidate structure state and return to the execution step S105.

[0138] Understandably, the current candidate structure state is eliminated, the next candidate structure state of the current candidate structure state is taken as the current candidate structure state, and the process returns to step S105.

[0139] E3: Check if there is a saved current optimal state.

[0140] If a saved current optimal state exists, then process E4 is executed.

[0141] It should be noted that if there is no saved current optimal state, the current candidate structure state is directly updated to the current optimal state.

[0142] Optionally, after process E3, the following may be further included:

[0143] Within the initial progressive level, if none of the k consecutive current candidate structural states satisfy the allowable constraints, then the next progressive level of the initial progressive level is selected from all progressive levels, and the next progressive level is used as the initial progressive level. Then, the process returns to step S104 until all progressive levels have been traversed.

[0144] Optionally, k can be set according to the actual situation, and no specific restrictions are made here.

[0145] It is understandable that, within the initial progressive level, if none of the k consecutive current candidate structural states satisfy the allowable constraints, and the current optimal state already satisfies the allowable constraints, or the current optimal state is empty, then the next progressive level of the initial progressive level is selected from all progressive levels.

[0146] E4: Compare the structural quality of the current optimal state with the structural quality of the current candidate structural state.

[0147] Optionally, after process E4, the following may be further included:

[0148] If the structural quality of the current candidate structural state is greater than that of the current optimal state, then the current candidate structural state is recorded as an alternative solution, and the current optimal state is not updated.

[0149] E5: If the structural quality of the current candidate structural state is less than the structural quality of the current optimal state, then the current candidate structural state is updated to the current optimal state.

[0150] E6: If the structural quality of the current candidate structural state is consistent with that of the current optimal state, then calculate the structural cost-effectiveness index of the current candidate structural state based on the mechanical performance results.

[0151] Specifically, the structural cost-effectiveness index is defined as the ratio of the improvement in structural performance to the cost of the increase in quality: .in, The structural cost-effectiveness index, For the improvement of structural performance, Incremental cost for quality.

[0152] The incremental cost of quality is from the current optimal state The total increase in mass up to the current candidate structure state. Its form is as follows: .in, The enhanced total volume is the current optimal state after optimization. The enhanced total volume of the current candidate structure state after optimization.

[0153] Structural performance improvement Candidate state Relative to the current optimal state The formula for calculating the combined improvement in equivalent stress margin and deformation margin is as follows: ;in, and For the weighting coefficients, satisfying Here you can adjust the weighting method; the default is equal weighting. , To allow equivalent stress, The maximum allowable deformation.

[0154] E7: Compare the structural cost-effectiveness index with the structural cost-effectiveness index of the current optimal state.

[0155] E8: If the structural cost-effectiveness index is greater than the structural cost-effectiveness index of the current optimal state, then update the candidate structural state to the current optimal state.

[0156] It should be noted that if the structural cost-effectiveness index is not greater than the structural cost-effectiveness index of the current optimal state, then the current optimal state is retained.

[0157] S107: After the candidate structure state sequence within the initial progressive level has been traversed, the next progressive level of the initial progressive level is selected from all progressive levels. The next progressive level is then used as the initial progressive level. The process returns to step S104 until all progressive levels have been traversed.

[0158] Understandably, the overall optimization loop terminates when all progressive levels have been traversed, or when the current optimal state has not been updated for m consecutive sub-levels.

[0159] S108: After all progressive levels have been traversed, output the current optimal state and the corresponding reinforced structural parameters and mechanical performance results.

[0160] Optionally, output the final retained optimal structure state. and its corresponding reinforced structural layout scheme, geometric parameters, and mass value And the maximum deformation obtained by finite element analysis verification and maximum equivalent stress .

[0161] It should be noted that this applies when all progressive levels have been traversed, or when the current optimal state is reached. If no sub-layer has been updated for m consecutive times, terminate the overall optimization and output the result. .

[0162] The value of m can be set according to the actual situation, and there are no specific restrictions here.

[0163] To facilitate a further understanding of the technical solution and beneficial effects of this application, specific examples are provided below.

[0164] Optionally, taking a 35kV oil-immersed transformer square tank as the optimization object, the optimization method provided in the above-described embodiments of this application is used to optimize the shell reinforcement structure. The basic parameters for tank base modeling are shown in Table 1, and the positions and dimensions of the outgoing terminals on the side walls are shown in Table 2. Specifically, side walls 2 (short axis) and 3 (long axis) have no outgoing terminals, side wall 1 (short axis) has one outgoing terminal, and side wall 4 (long axis) has two outgoing terminals. Table 3 shows the discrete levels of the reinforcement structure parameter optimization, which can be customized according to actual needs. In this example, the maximum allowable deformation of the side wall is 1.5 times the wall thickness, i.e. The selected material is Q235B, with an allowable equivalent stress value of [missing value]. a.

[0165] Table 1

[0166]

[0167] Table 2

[0168]

[0169] Table 3

[0170]

[0171] Following the optimization method described above, a progressive search was performed. The final optimization results are shown in Table 4, and the corresponding fuel tank modeling results are as follows: Figure 2 As shown, the deformation cloud map of the optimization result is as follows: Figure 3 As shown, the stress cloud diagram is as follows Figure 4 As shown in the stress cloud diagram (stress singularities have been excluded), the maximum deformation is less than 1.5 times the sidewall thickness (9 mm) according to the constraints, and the maximum allowable equivalent stress is 235 MPa. The optimization results meet the design requirements.

[0172] Table 4

[0173]

[0174] like Figure 2 The image shown is a modeling diagram of the fuel tank based on the optimization results of an embodiment of this application. Figure 2 As can be seen, the reinforcement structure of each panel is reasonably laid out, and the reinforcing ribs and reinforcing arches are arranged in the corresponding panel positions according to the optimization results. The overall structure is compact and meets the avoidance constraints of the outgoing end.

[0175] like Figure 3 The image shown is a deformation cloud diagram of the optimization results in an embodiment of this application. Figure 3 As can be seen, the maximum deformation of each panel under an external pressure load of 0.1 MPa is less than the allowable deformation of 9 mm. The deformation is evenly distributed and there are no areas with excessive local deformation, indicating that the reinforced structure effectively suppresses the deformation of the panels under external pressure.

[0176] like Figure 4 The image shown is a stress cloud diagram representing the optimization results of an embodiment of this application. Figure 4 As can be seen, the maximum equivalent stress of each panel under an external pressure load of 0.1MPa is less than the allowable equivalent stress of 235MPa. The stress distribution is reasonable, and there are no stress concentration areas after excluding stress singularities, indicating that the reinforced structure meets the strength requirements under vacuum process.

[0177] The above examples demonstrate that the optimization method for the transformer tank housing reinforcement structure provided in this application is not only applicable to conventional vacuum requirements, but can also be extended to transformer tank designs with high vacuum and higher voltage levels. Furthermore, the reliability of the results is ensured through direct finite element verification, demonstrating good engineering adaptability and scalability.

[0178] It should be noted that, based on the processes shown in S101-S108 above, this embodiment can achieve the following beneficial effects:

[0179] 1. The complex rib / arch hybrid selection problem is decomposed into three progressive levels: the baseline layer, the vertical reinforcement layer, and the horizontal reinforcement layer. Within each level, candidate structural states are directly generated by increasing the quality gradient, and finite element calculations are performed one by one. This avoids the high-dimensional curse of global search and the prediction error of surrogate models, and ensures the reliability of optimization results while significantly reducing computational costs.

[0180] 2. The structural cost-effectiveness index unifies the dimension of incremental cost of mass and increase in vacuum strength (measured by deformation suppression and stress margin), providing a quantitative basis for decision-making regarding the morphological switching between stiffeners and reinforced arches, as well as the increase in geometric dimensions.

[0181] 3. The mechanical properties of each candidate structural state are obtained through actual calculation using PyANSYS, with the maximum deformation of the sidewall and the maximum equivalent stress as the constraint criteria. There is no approximation error of the surrogate model, thus ensuring the engineering reliability of the optimization results under vacuum drying and vacuum oiling processes.

[0182] 4. The influence of side wall openings on the truncation of vacuum intensity path is incorporated into the candidate state generation rules. Vertical reinforcing ribs are automatically segmented when they encounter the exit end, and horizontal reinforcing ribs are automatically avoided when they encounter the exit end or vertical arch, thereby ensuring that the optimized scheme has good manufacturability and vacuum stability reliability.

[0183] 5. The progressive architecture decomposes the high-dimensional hybrid discrete optimization problem into several manageable sub-problems and customizes a specific optimization strategy for the special mechanical mechanism of vacuum external pressure strength and stiffness. Within each level, the search is directly performed according to the cost-effectiveness gradient of external pressure resistance, improving computational efficiency by two orders of magnitude compared to traditional global optimization methods. Furthermore, this method is deeply integrated with the PyAnsys toolchain, forming a complete closed loop from rapid single-plane static strength assessment to overall static strength verification, applicable to the digital intelligent design of transformer tanks and batch verification of vacuum strength.

[0184] like Figure 5 As shown in the figure, this application embodiment provides an architecture diagram of an optimization device for reinforcing the transformer tank shell. The optimization device specifically includes: a construction unit 100, a division unit 200, a determination unit 300, a generation unit 400, an analysis unit 500, an update unit 600, a feedback unit 700, and an output unit 800.

[0185] The building unit 100 is used to construct the structural state space based on the structural state vector; the structural state vector includes at least vertical strengthening structural parameters and horizontal strengthening structural parameters.

[0186] Dividing unit 200 is used to divide the structural state space into multiple progressive levels; the progressive levels include a base layer, a vertical reinforcement layer, or a horizontal reinforcement layer.

[0187] The dividing unit 200 is specifically used to: divide the unreinforced structural state in the structural state space into a base layer; divide all states in the structural state space that contain vertical reinforcement structures into vertical reinforcement layers; the vertical reinforcement structures include vertical stiffeners and vertical reinforcement arches; divide all states in the structural state space that have added transverse reinforcement structures on the basis of vertical reinforcement into transverse reinforcement layers; the transverse reinforcement structures include transverse stiffeners and transverse reinforcement arches.

[0188] The determining unit 300 is used to determine the starting progressive level from multiple progressive levels based on the transformer enclosure panel.

[0189] The determination unit 300 is specifically used to: determine the vertical reinforcing layer as the starting progressive layer when the transformer box panel is a long axis side panel; and determine the reference layer as the starting progressive layer when the transformer box panel is a short axis side panel.

[0190] The generation unit 400 is used to generate a sequence of candidate structural states according to the progressive rules within the initial progressive level.

[0191] The generation unit 400 is specifically used for: if the initial progressive level is the reference level, detecting whether the initial progressive level meets the allowable constraints; the allowable constraints are that the maximum deformation is not greater than the allowable deformation and the maximum equivalent stress is not greater than the allowable equivalent stress; if the initial progressive level does not meet the allowable constraints, then selecting the next progressive level from all progressive levels and using the next progressive level as the initial progressive level; within the initial progressive level, increasing the number of strengthening structures in an incremental manner, and storing the first configuration state after the increment as a candidate structure state in the candidate structure state sequence; when increasing the number of strengthening structures cannot meet the constraint conditions, increasing the number of strengthening structures in an incremental manner according to the geometric dimensions, and storing the second configuration state after the increment as a candidate structure state in the candidate structure state sequence, the geometric dimensions... This includes height and thickness; the constraint condition is that the maximum equivalent stress of the candidate structural state does not exceed the allowable equivalent stress, and the maximum deformation does not exceed the allowable deformation; when increasing the geometric dimensions still cannot meet the constraint conditions, the stiffeners are replaced with stiffening arches in order from the middle position to the edge position, and the replaced configuration state is stored as a candidate structural state in the candidate structural state sequence; when all stiffening structures are replaced with stiffening arches and the constraint conditions still cannot be met, the next progressive level of the initial progressive level is triggered to increase; during the generation of candidate structural states, if the path of the vertical or horizontal stiffening structure intersects with the exit end, the corresponding stiffening structure is truncated into independent segments at the exit end position, and the segmented stiffening structure is stored as a candidate structural state in the candidate structural state sequence.

[0192] Analysis unit 500 is used to perform static analysis on the current candidate structural state in the candidate structural state sequence to obtain mechanical performance results; the mechanical performance results include structural mass, maximum deformation and maximum equivalent stress.

[0193] Analysis unit 500 is specifically used for: establishing a parametric geometric model through a finite element analysis solver and defining the material properties of the parametric geometric model; adding fixed support boundary constraints and uniformly distributed external pressure loads to the defined parametric geometric model; performing static structural analysis on the candidate structural states in the candidate structural state sequence based on the added parametric geometric model to obtain the maximum deformation and maximum equivalent stress; and calculating the structural mass based on the reinforced structural geometry and steel density corresponding to the candidate structural state.

[0194] The update unit 600 is used to update the current optimal state based on the mechanical performance results and the current candidate structure state.

[0195] The update unit 600 is specifically used for: determining whether the maximum deformation and maximum equivalent stress meet the allowable constraints; if the maximum deformation and maximum equivalent stress do not meet the allowable constraints, then the next candidate structural state of the current candidate structural state is taken as the current candidate structural state, and the process is returned to the execution analysis unit 500; if the maximum deformation and maximum equivalent stress meet the allowable constraints, then it checks whether there is a saved current optimal state; if there is a saved current optimal state, then it compares the structural mass of the current optimal state with the structural mass of the current candidate structural state; if the structural mass of the current candidate structural state is less than the structural mass of the current optimal state, then the current candidate structural state is updated to the current optimal state; if the structural mass of the current candidate structural state is consistent with the structural mass of the current optimal state, then it calculates the structural cost-effectiveness index of the current candidate structural state based on the mechanical performance results; it compares the structural cost-effectiveness index with the structural cost-effectiveness index of the current optimal state; if the structural cost-effectiveness index is greater than the structural cost-effectiveness index of the current optimal state, then the candidate structural state is updated to the current optimal state.

[0196] Feedback unit 700 is used to select the next progressive level from all progressive levels after the candidate structure state sequence within the initial progressive level has been traversed, and then return to the execution generation unit after taking the next progressive level as the initial progressive level, until all progressive levels have been traversed.

[0197] Output unit 800 is used to output the current optimal state and the corresponding reinforced structural parameters and mechanical performance results after all progressive levels have been traversed.

[0198] In summary, the mass increment and efficiency improvement corresponding to each candidate structural state can be directly quantified and compared through static analysis. This establishes a quantitative mapping relationship between the mass and efficiency of stiffeners and reinforced arches in terms of external pressure stability, providing a clear decision-making basis for selecting the optimal scheme under the same mass increment. Simultaneously, the progressive hierarchical partitioning effectively constrains the search direction, avoids disordered traversal of the entire space, and significantly reduces computational costs.

[0199] Combination Figure 5 As shown, the optimization device further includes a recording unit, which records the current candidate structure state as an alternative scheme and does not update the current optimal state if the structural quality of the current candidate structure state is greater than the structural quality of the current optimal state.

[0200] Combination Figure 5 The optimization device, as shown, further includes a filtering unit, which, if k consecutive current candidate structural states do not satisfy the allowable constraints within the initial progressive level, filters out the next progressive level from all progressive levels, uses the next progressive level as the initial progressive level, and then returns to execute the step of generating a sequence of candidate structural states according to the progressive rules within the initial progressive level, until all progressive levels have been traversed.

[0201] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0202] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An optimization method for the reinforcing structure of a transformer tank shell, characterized in that, include: Construct the structural state space based on the structural state vector; The structural state vector includes at least vertical reinforcement structural parameters and horizontal reinforcement structural parameters; The structural state space is divided into multiple progressive levels; the progressive levels include a base layer, a vertical reinforcement layer, or a horizontal reinforcement layer; The starting progressive level is determined from the multiple progressive levels based on the transformer enclosure panel; Within the initial progressive level, a sequence of candidate structural states is generated according to the progressive rules; Static analysis is performed on the current candidate structure state in the candidate structure state sequence to obtain the mechanical performance results; The mechanical performance results include structural mass, maximum deformation, and maximum equivalent stress. The current optimal state is updated based on the mechanical performance results and the current candidate structure state. After the candidate structure state sequence within the initial progressive level has been traversed, the next progressive level of the initial progressive level is selected from all progressive levels. The next progressive level is then used as the initial progressive level. The process then returns to the initial progressive level to generate the candidate structure state sequence according to the progressive rules, until all progressive levels have been traversed. After all progressive levels have been traversed, the current optimal state and the corresponding reinforced structural parameters and mechanical performance results are output.

2. The method according to claim 1, characterized in that, The step of determining the starting progressive level from multiple progressive levels based on the transformer enclosure panel includes: When the transformer housing panel is a long axis side panel, the vertical reinforcing layer is determined as the starting progressive layer; When the transformer housing panel is a short-axis side panel, the reference layer is determined as the starting progressive layer.

3. The method according to claim 1, characterized in that, The division of the structural state space into multiple progressive levels includes: The unreinforced structural states in the structural state space are divided into the reference layer; All states containing vertically reinforcing structures in the structural state space are divided into vertically reinforcing layers; the vertically reinforcing structure includes vertical reinforcing ribs and vertically reinforcing arches; All states in the structural state space that have added transverse reinforcement on the basis of vertical reinforcement are classified as transverse reinforcement layers; the transverse reinforcement structure includes transverse reinforcing ribs and transverse reinforcing arches.

4. The method according to claim 1, characterized in that, The step of generating a candidate structure state sequence according to the progressive rules within the initial progressive level includes: If the starting progressive level is the reference level, it is checked whether the starting progressive level meets the allowable constraints; the allowable constraints are that the maximum deformation is not greater than the allowable deformation and the maximum equivalent stress is not greater than the allowable equivalent stress. If the starting progressive level does not satisfy the allowable constraint, then the next progressive level of the starting progressive level is selected from all progressive levels, and the next progressive level is used as the starting progressive level. Within the initial progressive level, the number of reinforcement structures is increased in an incremental manner, and the first configuration state after the increase is stored as a candidate structure state in the candidate structure state sequence. When increasing the number of reinforcing structures cannot meet the constraints, the structure is incremented according to the geometric dimensions. The second configuration state after the increment is stored as a candidate structure state in the candidate structure state sequence. The geometric dimensions include height and thickness. The constraints are that the maximum equivalent stress of the candidate structure state does not exceed the allowable equivalent stress, and the maximum deformation does not exceed the allowable deformation. When increasing the geometric dimensions still cannot meet the constraints, the stiffeners are replaced with stiffening arches in order from the middle position to the edge position, and the replaced configuration state is stored as a candidate structural state in the candidate structural state sequence. If the constraint condition still cannot be met after all the reinforcing structures have been replaced with the reinforcing arch, the next progressive level of the initial progressive level is triggered to increase. During the generation of candidate structure states, if the path of the vertical or horizontal reinforcing structure intersects with the exit end, the corresponding reinforcing structure is truncated into independent segments at the exit end position, and the segmented reinforcing structures are stored as candidate structure states in the candidate structure state sequence.

5. The method according to claim 1, characterized in that, The static analysis of the candidate structural states in the candidate structural state sequence to obtain mechanical performance results includes: A parametric geometric model is established using a finite element analysis solver, and the material properties of the parametric geometric model are defined. Add fixed support boundary constraints and uniformly distributed external pressure loads to the defined parametric geometric model; Based on the added parametric geometric model, static structural analysis of the candidate structural states in the candidate structural state sequence is performed to obtain the maximum deformation and the maximum equivalent stress. The structural mass is calculated based on the reinforced structural geometry and steel density corresponding to the candidate structural states.

6. The method according to claim 1, characterized in that, The step of updating the current optimal state based on the mechanical performance results and the candidate structural states includes: Determine whether the maximum deformation and the maximum equivalent stress satisfy the allowable constraints; If the maximum deformation and the maximum equivalent stress do not meet the allowable constraints, then the next candidate structural state of the current candidate structural state is taken as the current candidate structural state, and the process returns to the step of performing static analysis on the current candidate structural state in the candidate structural state sequence to obtain the mechanical performance results. If the maximum deformation and the maximum equivalent stress satisfy the allowable constraints, then check whether there is a saved current optimal state; If the saved current optimal state exists, then the structural quality of the current optimal state is compared with the structural quality of the current candidate structural state. If the structural quality of the current candidate structural state is less than the structural quality of the current optimal state, then the current candidate structural state is updated to the current optimal state; If the structural quality of the current candidate structural state is consistent with the structural quality of the current optimal state, then the structural cost-effectiveness index of the current candidate structural state is calculated based on the mechanical performance results. Compare the structural cost-effectiveness index with the structural cost-effectiveness index of the current optimal state; If the structural cost-effectiveness index is greater than the structural cost-effectiveness index of the current optimal state, then the candidate structural state is updated to the current optimal state.

7. The method according to claim 6, characterized in that, Also includes: If the structural quality of the current candidate structural state is greater than the structural quality of the current optimal state, then the current candidate structural state is recorded as an alternative scheme, and the current optimal state is not updated.

8. The method according to claim 6, characterized in that, Also includes: If k consecutive candidate structural states do not satisfy the allowable constraints within the initial progressive level, then the next progressive level of the initial progressive level is selected from all progressive levels. After the next progressive level is used as the initial progressive level, the process returns to the initial progressive level and generates a sequence of candidate structural states according to the progressive rules, until all progressive levels have been traversed.

9. An optimized device for reinforcing the casing of a transformer tank, characterized in that, include: Construction unit, used to construct the structural state space based on the structural state vector; The structural state vector includes at least vertical reinforcement structural parameters and horizontal reinforcement structural parameters; A partitioning unit is used to divide the structural state space into multiple progressive levels; the progressive levels include a base layer, a vertical reinforcement layer, or a horizontal reinforcement layer; A determining unit is configured to determine the starting progressive level from a plurality of progressive levels based on the transformer housing panel; The generation unit is used to generate a sequence of candidate structural states according to the progression rules within the initial progressive level; The analysis unit is used to perform static analysis on the current candidate structural state in the candidate structural state sequence to obtain mechanical performance results; the mechanical performance results include structural mass, maximum deformation, and maximum equivalent stress. The update unit is used to update the current optimal state based on the mechanical performance results and the current candidate structure state; The feedback unit is used to filter out the next progressive level from all progressive levels after the candidate structure state sequence in the starting progressive level has been traversed, and then return to the execution generation unit after the next progressive level is used as the starting progressive level, until all progressive levels have been traversed. The output unit is used to output the current optimal state and the corresponding reinforcement structure parameters and mechanical performance results after all progressive levels have been traversed.

10. The apparatus according to claim 9, characterized in that, The determining unit is specifically used for: When the transformer housing panel is a long axis side panel, the vertical reinforcing layer is determined as the starting progressive layer; When the transformer housing panel is a short-axis side panel, the reference layer is determined as the starting progressive layer.

Images