Rectangular winding local strengthening structure design method, rectangular winding assembly and effectiveness verification method of local strengthening structure

Abstract

The invention discloses a design method of a local strengthening structure of a rectangular winding, a rectangular winding assembly and an effectiveness verification method of the local strengthening structure. The design method for the local strengthening structure of the rectangular winding comprises the following steps: acquiring mechanical response of the rectangular winding under a short-circuit working condition through a magnetic field-solid mechanical field coupling simulation model; based on the mechanical response, obtaining stress distribution characteristics of the rectangular winding at the corners and on the long sides; according to the stress distribution characteristics of the corner, determining structural parameters of a corner target strengthening structure for fitting the corner; and according to the stress distribution characteristics of the long sides, determining the structural parameters of the long side targeting strengthening structure for fitting the long sides. According to the invention, accurate identification and targeted reinforcement of the high-stress area of the rectangular winding under the short-circuit working condition can be realized.

Description

Technical Field

[0001] This invention relates to the field of power system technology, and in particular to a design method for a local reinforcement structure of a rectangular winding, and a method for verifying the effectiveness of a rectangular winding assembly and a local reinforcement structure. Background Technology

[0002] Amorphous alloy transformers are widely used in power distribution due to their low no-load loss and high efficiency. However, due to the brittleness of amorphous alloy core materials and their high sensitivity to mechanical stress, their winding structure is prone to irreversible deformation under the enormous electromagnetic forces during short-circuit operations, leading to core performance degradation and even equipment failure. This is especially true for amorphous alloy transformers with rectangular cross-section windings, whose geometric characteristics result in a significantly non-uniform distribution of electromagnetic forces within the windings under short-circuit current impacts, with the corners and the middle of the long side becoming the weakest points with the most severe mechanical response.

[0003] In existing technologies, the support structure designs adopted to improve the short-circuit withstand capability of rectangular windings are mainly divided into two categories: one is an integral rigid frame constraint, such as the "A type of amorphous alloy transformer winding frame with short-circuit withstand capability" disclosed in Chinese utility model patent CN209804425U. This scheme forms the outer frame of the winding by combining U-shaped or J-shaped stainless steel plates, and applies pre-tightening force with PET straps to counteract the radial electromagnetic force between the high and low voltage windings. However, this structure uses a right-angle splicing method at the winding corners, which fails to conform to the curvature transition of the actual winding corners, resulting in local hard contact and exacerbating the tangential stress concentration. At the same time, its integral rigid frame does not specifically reinforce the middle of the long side, resulting in a significant risk of radial bulging deformation in this area under short-circuit conditions.

[0004] Another type is the embedded epoxy support structure, such as the "Amorphous Alloy Transformer Winding Structure with High Short-Circuit Resistance" in Chinese Utility Model Patent CN 205845664U, which provides radial support by setting an epoxy glass cloth plate and an integral epoxy cylinder on the inner side of the winding. Although this method can suppress the collapse of the long axis of the low-voltage winding to a certain extent, its support structure is a monolithic form with uniform thickness, which does not take into account the difference in stress distribution in different areas of the winding under short-circuit conditions, resulting in unreasonable material stiffness distribution—excessive stiffness may occur in the middle of the long axis, resulting in material waste, while the transition area near the corner still has the risk of deformation due to insufficient support; in addition, this solution does not involve any effective measures to alleviate the tangential stress concentration at the corner. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, one objective of this invention is to propose a method for designing a locally reinforced structure for rectangular windings, achieving accurate identification and targeted reinforcement of high-stress regions in rectangular windings under short-circuit conditions.

[0006] The present invention also proposes a rectangular winding assembly.

[0007] This invention also proposes a method for verifying the structural effectiveness of locally reinforced structures.

[0008] The first aspect of this invention provides a method for designing a locally reinforced rectangular winding structure. The rectangular winding includes a pair of long sides and a pair of short sides, adjacent long and short sides are connected by a corner, and the length of the long side is greater than the length of the short side. The method for designing a locally reinforced rectangular winding structure includes the following steps:

[0009] Step S1: Obtain the mechanical response of the rectangular winding under short-circuit conditions using a magnetic field-solid mechanics field coupling simulation model;

[0010] Step S2: Based on the mechanical response, obtain the stress distribution characteristics of the rectangular winding at the corner and on the long side;

[0011] Step S3: Determine the structural parameters of the corner-targeting reinforcement structure used to fit the corner based on the stress distribution characteristics of the corner;

[0012] Step S4: Determine the structural parameters of the long-side targeted reinforcement structure used to fit the long side based on the stress distribution characteristics of the long side.

[0013] Furthermore, the corner-targeting reinforcement structure includes a first straight segment, a transition curve segment, and a second straight segment connected in sequence. The first straight segment and the second straight segment are used to fit the adjacent long side and short side of the rectangular winding, respectively, and the transition curve segment is used to fit the corner of the rectangular winding between the adjacent long side and short side.

[0014] The width of the transition curve segment is equal to the axial height of the rectangular winding to cover the corner at the axial height of the rectangular winding, and the arc length of the transition curve segment matches the arc length of the corner to cover the corner in the arc extension direction of the corner.

[0015] The thickness direction of the transition curve segment is perpendicular to the corner surface and points away from the rectangular winding.

[0016] In step S3, the structural parameters of the corner-targeted reinforcement structure include the thickness of the transition curve segment.

[0017] Furthermore, step S3 specifically includes the following sub-steps:

[0018] Step S31: Based on the stress distribution characteristics of the rectangular winding at the corner, extract the maximum tangential contact stress value of the surface of the rectangular winding at the corner;

[0019] Step S32: Based on the maximum tangential contact stress value and the effective bearing length of the rectangular winding in the radial direction at the corner, determine the equivalent radial load intensity of the corner-targeted reinforcement structure per unit axial height;

[0020] Step S33: Simplify the transition curve segment of the corner-targeted reinforcement structure into a circular arc beam model with fixed supports at both ends. The radius of curvature of the circular arc beam model is the same as that of the transition curve segment, and it bears the uniformly distributed radial pressure at the corner corresponding to the equivalent radial load intensity at the corner.

[0021] Step S34: Based on the stress characteristics of the circular arc beam model under uniformly distributed radial pressure at the rotation angle, calculate the first maximum bending moment borne by the circular arc beam model at the constrained end;

[0022] Step S35: Based on the first maximum bending moment and the allowable bending stress of the material used in the corner-targeted reinforcement structure, calculate the thickness of the transition curve segment in the radial direction.

[0023] Furthermore, the corner-targeted reinforcement structure is constructed as a glass fiber reinforced epoxy resin composite material part.

[0024] Furthermore, the long-side targeted reinforcement structure includes a support plate extending along the long side of the rectangular winding;

[0025] The length direction of the support plate is parallel to the long side, and the two ends of the support plate in the length direction extend to the adjacent corner targeted reinforcement structure. The width of the support plate is the same as the axial height of the rectangular winding so as to cover the long side in the axial height of the rectangular winding. The thickness direction of the support plate is perpendicular to the surface of the long side and points away from the rectangular winding.

[0026] In step S4, the structural parameters of the long-side targeted reinforcement structure include the thickness of the support plate.

[0027] Furthermore, step S4 specifically includes the following sub-steps:

[0028] Step S41: Based on the stress distribution characteristics of the rectangular winding at the long side, extract the maximum radial electrodynamic force of the rectangular winding on the surface of the long side;

[0029] Step S42: Based on the maximum radial electrodynamic force and the width of the support plate, determine the equivalent radial load intensity of the long side acting on the long side targeted reinforcement structure.

[0030] Step S43: Simplify the long-side targeted reinforcement structure into a straight beam model with a span of simply supported at both ends. The straight beam model bears the uniformly distributed radial pressure on the long side corresponding to the equivalent radial load intensity on the long side.

[0031] Step S44: Based on the stress characteristics of the straight beam model under uniformly distributed radial pressure along its long side, calculate the second maximum bending moment borne by the straight beam model at the mid-span section.

[0032] Step S45: Determine the thickness of the support plate based on the second maximum bending moment and the allowable bending stress of the material used in the support plate.

[0033] Furthermore, the support plate is constructed of sinusoidal corrugated steel.

[0034] A second aspect of the present invention provides a rectangular winding assembly, comprising a rectangular winding, a corner-targeting reinforcement structure, and a long-side-targeting reinforcement structure. The rectangular winding includes a pair of long sides and a pair of short sides, adjacent long and short sides being connected by a corner, with the length of the long side being greater than the length of the short side. The corner-targeting reinforcement structure includes a first straight segment, a transition curve segment, and a second straight segment connected in sequence. The first and second straight segments are respectively used to conform to adjacent long and short sides of the rectangular winding, and the transition curve segment is used to conform to the corner of the rectangular winding between adjacent long and short sides. The long-side-targeting reinforcement structure includes a support plate extending along the long side of the rectangular winding, with both ends of the support plate extending to adjacent corner-targeting reinforcement structures. An epoxy adhesive layer is provided between the corner-targeting reinforcement structure and the corner. The two ends of the support plate in the length direction are fixedly connected to rigid metal clamps on the rectangular winding by bolts with a preset torque T.

[0035] The formula for calculating the preset torque T is:

[0036] ;

[0037] in, The torque coefficient, This refers to the standard value of bolt preload. This refers to the nominal diameter of the bolt.

[0038] A third aspect of the present invention provides a method for verifying the effectiveness of a locally reinforced structure. Further, applied to a rectangular winding assembly according to a second aspect of the present invention, the method comprises the following steps:

[0039] Obtain the first parameter characterizing the structural characteristics of the corner-targeted reinforcement structure under actual short-circuit conditions, and the second parameter characterizing the structural characteristics of the long-side-targeted reinforcement structure under actual short-circuit conditions;

[0040] The first parameter is compared with the first preset threshold. If the first parameter does not exceed the first preset threshold, the corner-targeted reinforcement structure is determined to be effective.

[0041] The second parameter is compared with the second preset threshold. If the second parameter does not exceed the second preset threshold, the long-side targeted reinforcement structure is determined to be effective.

[0042] Furthermore, the first parameter is the stress value measured at the transition curve segment of the corner-targeted reinforcement structure under short-circuit conditions;

[0043] The first preset threshold is the allowable stress of the material used in the corner-targeted reinforcement structure divided by the safety factor;

[0044] The second parameter includes the stress value measured by the support plate under actual short-circuit conditions, and the radial displacement value of the middle of the long side of the rectangular winding.

[0045] The second preset threshold includes: the allowable stress of the material used in the support plate divided by the safety factor, and the maximum radial displacement of the long side of the rectangular winding under short-circuit conditions determined by the magnetic field-solid mechanics field coupling simulation model.

[0046] As can be seen from the technical solution, the embodiments provided by the present invention have the following advantages:

[0047] (1) This invention obtains the mechanical response of a rectangular winding under short-circuit conditions through a magnetic field-solid mechanics field coupling simulation model. Compared with traditional two-dimensional models and single physical field models, it can more accurately identify the mechanical response at the corners and long sides of the rectangular winding, providing a reliable basis for strengthening structural design and avoiding blind strengthening.

[0048] (2) Based on this, for the two typical weak parts, corner and long side, corner-targeted reinforcement structure matching the stress state of the corner and long side-targeted reinforcement structure matching the stress state of the long side are set up respectively, and their respective structural parameters are determined. Compared with the technical means of overall reinforcement or single local reinforcement of the support structure in related technologies, the structural parameters of the local reinforcement structure are designed based on the stress distribution under short-circuit conditions, which can effectively disperse local stress and suppress deformation, make up for the unresolved defects of local stress concentration in previous support structures, and reduce the material waste caused by the overall reinforcement method. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a step-by-step diagram of the design method for a local reinforcement structure of a rectangular winding;

[0051] Figure 2 It is a stress distribution cloud diagram of a rectangular winding;

[0052] Figure 3It is a displacement distribution cloud map of a rectangular winding;

[0053] Figure 4 These are the load-displacement curves for corrugated steel plate components and flat plate components;

[0054] Figure 5 This is a schematic diagram of an elastic cushioning pad;

[0055] Figure 6 This is a structural schematic diagram of a rectangular winding assembly;

[0056] Figure 7 It is based on Figure 6 Cross-sectional view at A-A';

[0057] Figure 8 It is based on Figure 6 Cross-sectional view at B-B';

[0058] Figure 9 It is a method for verifying the effectiveness of locally reinforced structures.

[0059] Figure label:

[0060] Rectangular winding assembly 100;

[0061] Rectangular winding 1, low-voltage rectangular winding 11, high-voltage rectangular winding 12;

[0062] Corner-targeted enhancement structure 2;

[0063] Long-side targeted enhancement structure 3;

[0064] Elastic cushioning pad 4;

[0065] Epoxy resin support 5. Detailed Implementation

[0066] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0067] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0068] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0069] The following is for reference. Figures 1-9 This invention describes a design method for a rectangular winding local reinforcement structure, a rectangular winding assembly, and a method for verifying the effectiveness of the local reinforcement structure.

[0070] like Figure 1 and Figure 6 As shown, a first aspect of the present invention provides a method for designing a locally reinforced rectangular winding structure. The rectangular winding 1 includes a pair of long sides and a pair of short sides, adjacent long sides and short sides are connected by a corner, the length of the long side is greater than the length of the short side, and the corner is a rounded corner with a preset radius of curvature. The method for designing a locally reinforced rectangular winding structure includes the following steps:

[0071] like Figures 1-3 As shown, step S1: The mechanical response of rectangular winding 1 under short-circuit conditions is obtained through a magnetic field-solid mechanics coupling simulation model. Specifically, based on the actual structure and material parameters of the amorphous alloy transformer, a magnetic field-solid mechanics coupling model including the core, high and low voltage rectangular windings, and oil tank is established in the finite element simulation software. This model accurately imports the geometric characteristic parameters of rectangular winding 1, including the dimensions of a pair of long sides and a pair of short sides, the radius of curvature of the rotation angle, the axial height, and the radial thickness, and integrates the electromagnetic-mechanical material properties of the amorphous alloy core and the winding conductors, such as permeability, conductivity, Young's modulus, Poisson's ratio, and yield strength.

[0072] According to the provisions of national standard GB / T 1094.5—2008 regarding the short-circuit withstand capacity of power transformers, a transient current excitation conforming to the physical characteristics of three-phase short-circuit current is applied, and its expression is:

[0073]

[0074]

[0075]

[0076] In the formula, I k T is the effective value of the short-circuit current. k For short-circuit current i k The cycle.

[0077] I A I B I C These are the instantaneous short-circuit currents of the three phases A, B, and C of the transformer, respectively; I K ω is the steady-state effective value of the short-circuit current; ω is the system angular frequency; t is time; i k T represents the instantaneous value of the short-circuit current. k This is the system decay time constant, reflecting how fast the short-circuit current decays;

[0078] T k =L k / R k L k For the equivalent inductance of the short-circuit loop, R k This is the equivalent resistance of the short-circuit loop.

[0079] The leakage magnetic field distribution of the winding and the resulting Lorentz force under short-circuit conditions are calculated in the magnetic field module, and this electromagnetic force is automatically transferred as a load to the solid mechanics module, achieving bidirectional coupling solution of electromagnetic and structural fields. Simultaneously, based on actual assembly constraints, amorphous core fixed supports are set in the model to restrict the axial degrees of freedom of the winding, and preload boundary conditions are applied to the upper surface of the winding. Local mesh refinement is performed in key areas (especially corners and the middle of long sides) to accurately capture the distribution of high-gradient stresses.

[0080] The dynamic mechanical response of rectangular winding 1 during the short circuit process was obtained by simulating the 60%–110% rated short-circuit current condition using a transient solver, including the stress and displacement field distribution. This provides a quantitative basis for the subsequent design of targeted reinforcement structures.

[0081] Step S2: Based on the mechanical response, obtain the stress distribution characteristics of the rectangular winding 1 at the corner and on the long side;

[0082] like Figure 2 and Figure 3 As shown, after solving the magnetic field-solid mechanics coupled simulation model, stress distribution cloud maps and displacement distribution cloud maps of rectangular winding 1 were obtained, which were used to characterize the stress and displacement distribution of the simulation model under short-circuit conditions, respectively. The stress distribution cloud map clearly reflects a significant stress concentration phenomenon at the corner of rectangular winding 1, with the maximum stress value being much higher than in other areas, indicating that this location is a weak point in the structural strength. The displacement distribution cloud map shows that the middle of the long side of rectangular winding 1, especially the outer long side of the high-voltage winding, exhibits a significant outward bulging deformation trend under the action of radial electromagnetic force, with the displacement amplitude reaching its peak at the midpoint of the long side. These simulation results jointly verify the typical mechanical response characteristics of rectangular winding 1 under short-circuit conditions: "high stress concentration at the corner" and "large radial displacement at the middle of the long side," providing a key basis for the subsequent design of a zoned targeted reinforcement structure.

[0083] Step S3: Determine the structural parameters of the corner-targeting reinforcement structure 3 used to fit the corner based on the stress distribution characteristics of the corner;

[0084] like Figure 6 As shown, the corner-targeting reinforcement structure 3 is further constructed as an L-shaped bonding component. The corner-targeting reinforcement structure 3 includes a first straight segment, a transition curve segment, and a second straight segment connected in sequence. The first straight segment and the second straight segment are used to bond to the adjacent long side and short side of the rectangular winding 1, respectively, and the transition curve segment is used to bond to the corner of the rectangular winding 1 between the adjacent long side and short side.

[0085] To achieve full coverage reinforcement of the corner, the transition curve segment is geometrically designed as follows: the width of the transition curve segment is equal to the axial height of the rectangular winding 1 to cover the corner at the axial height of the rectangular winding 1; the arc length of the transition curve segment matches the arc length of the corner to cover the corner in the arc extension direction, ensuring a gapless fit in the arc extension direction of the corner; the thickness direction of the transition curve segment is perpendicular to the corner surface and points away from the rectangular winding 1 to effectively resist the outward deformation tendency caused by short-circuit electromagnetic force; among them, the structural parameters of the corner-targeted reinforcement structure 3 include the thickness dimension of the transition curve segment. The core structural parameter of the corner-targeted reinforcement structure 3 is the thickness dimension of the transition curve segment in the radial direction. This parameter directly determines its bending load-bearing capacity and is a key design variable to ensure the reinforcement effect.

[0086] It should also be noted that the rectangular winding 1 is a square ring and includes a low-voltage rectangular winding 11 and a high-voltage rectangular winding 12 arranged sequentially from the inside to the outside along its own radial direction. The rotation angle here includes the inner rotation angle on the low-voltage rectangular winding 11 and the outer rotation angle on the high-voltage rectangular winding 12.

[0087] To scientifically and quantitatively determine the thickness of the transition curve segment, step S3 is further refined into the following sub-steps:

[0088] Step S31: Based on the stress distribution characteristics of the rectangular winding 1 at the corner, extract the maximum tangential contact stress value of the surface of the rectangular winding 1 at the corner.

[0089] Specifically, in step S31, based on the stress distribution cloud map of the rectangular winding 1 under short-circuit conditions obtained in step S1, the maximum tangential contact stress value on the surface of the corner conductor is extracted (denoted as ). This value characterizes the most severe local stress state at the corner and serves as a reference input for subsequent load equivalence.

[0090] Step S32: Based on the maximum tangential contact stress value and the effective bearing length of the rectangular winding 1 in the radial direction at the corner, determine the equivalent radial load intensity of the corner-targeted reinforcement structure 3 per unit axial height.

[0091] Combined with the maximum tangential contact stress value The effective radial load length ω of rectangular winding 1 at the corner c The equivalent radial load intensity q acting on the corner-targeted reinforcement structure 3 per unit axial height is calculated, and its expression is:

[0092] ;

[0093] Where, ω c The effective radial length of the contact surface between the corner-targeted reinforcement structure 3 and the rectangular winding 1 at the corner is defined as the equivalent projection length of the contact area between the corner-targeted reinforcement structure 3 and the rectangular winding 1 on a section perpendicular to the axial height of the rectangular winding 1. Its physical meaning is the effective bearing length corresponding to the equivalent conversion of the curved surface contact pressure into a line load.

[0094] Step S33: Simplify the transition curve segment of the corner-targeted reinforcement structure 3 into a circular arc beam model with fixed supports at both ends. The radius of curvature of the circular arc beam model is the same as the radius of curvature of the transition curve segment, and it bears the uniformly distributed radial pressure at the corner corresponding to the equivalent radial load intensity at the corner.

[0095] Since the curvature of the transition curve segment is consistent with that of the rectangular winding 1, its mechanical behavior can be reasonably simplified to a circular arc beam model with fixed ends. The radius of curvature of this model... It has the same radius of curvature as the actual transition curve segment, and thus the same radius of curvature as the corner, and bears the uniformly distributed radial pressure of the corner, which is converted from the above load intensity q, and the direction is towards the center of curvature.

[0096] Step S34: Based on the stress characteristics of the circular arc beam model under uniformly distributed radial pressure at the rotation angle, calculate the first maximum bending moment borne by the circular arc beam model at the constrained end;

[0097] Based on the analytical theory of internal forces in structural mechanics regarding a circular arch with fixed ends under uniformly distributed radial pressure, calculate the first maximum bending moment borne by this curved beam model at the constrained ends. For the case covering an arc segment with an approximately 90° turn, the bending moment can be expressed as:

[0098] ;

[0099] Wherein, k is a dimensionless bending moment coefficient, the value of which is related to the central angle of the circular arch. In this embodiment, the circular arch beam model covers the arc segment of the rectangular winding 1 with a rotation angle of about 90°. According to the internal force analysis theory of the circular arch with fixed ends under uniform radial load, the corresponding bending moment coefficient k≈0.08; R is the radius of curvature of the circular arch beam model.

[0100] It should be further explained that, in order to construct a mechanical model suitable for beam theory analysis, the complex distributed pressure acting on the corner-targeted strengthening structure 3 needs to be reasonably equivalentd to obtain the maximum tangential compressive stress from the simulation. As the design reference stress, it is equivalent to a radially distributed load acting on the centroidal axis of the corner-targeted reinforcement structure 3 (i.e., the spatial curve that connects the centroids of each section along the bending direction of the corner-targeted reinforcement structure 3 and bends together with the corner-targeted reinforcement structure 3).

[0101] Step S35: Based on the first maximum bending moment and the allowable bending stress of the material used in the corner-targeted reinforcement structure 3, calculate the thickness of the transition curve segment in the radial direction.

[0102] Based on the first maximum bending moment M -max and the allowable bending stress of the material used in the corner-targeted reinforcement structure 3 [ The cross-section is designed based on the bending strength formula in mechanics of materials. The critical section of the transition curve segment is considered to have a width of b (i.e., the axial height of rectangular winding 1) and a thickness of t. -pad A rectangular cross-section, whose section modulus S1 = b*t -pad 2 / 6.

[0103] From the strength condition The minimum required thickness can be obtained by solving for this:

[0104] .

[0105] This determines the thickness of the transition curve segment in the radial direction, ensuring that it has sufficient bending strength and structural reliability under short-circuit conditions.

[0106] Furthermore, the corner-targeted reinforcement structure 3 is constructed as a glass fiber reinforced epoxy resin composite material part.

[0107] Specifically, using glass fiber reinforced epoxy resin with a glass fiber mass fraction of 10% as the molding material, compared with traditional pure epoxy resin, its tensile strength is increased by 76%, flexural strength by 42%, and impact strength by 178% (see Table 1), which significantly enhances the material's load-bearing capacity and resistance to damage in high stress concentration areas.

[0108] Table 1 Comparison of Mechanical Strength between Composite Materials and Pure Epoxy Resin Materials

[0109]

[0110] This composite material not only possesses excellent mechanical properties but also exhibits good electrical insulation and processability. It can be molded in one step using a high-precision mold to create an L-shaped structure that perfectly matches the geometry of the rectangular winding 1's corner. Before installation, the surface of the corner-targeted reinforcement structure 3 is precision-polished and cleaned with anhydrous isopropanol to ensure a gapless fit with the winding conductor surface. During installation, a high-strength insulating epoxy structural adhesive is applied to the interface, ensuring a firm structural connection while maintaining electrical insulation performance, thereby effectively suppressing stress concentration and insulation damage risks at the corner under short-circuit conditions.

[0111] It should be further explained that the rectangular winding 1 of the present invention has a square ring structure, which includes a low-voltage rectangular winding 11 and a high-voltage rectangular winding 12 arranged sequentially from the inside to the outside along its own radial direction. Accordingly, "corner" refers not only to the outer corner of the high-voltage rectangular winding 12, but also to the inner corner of the low-voltage rectangular winding 11. Since both the high-voltage and low-voltage windings will experience significant tangential stress concentration at their respective corners due to electromagnetic force under short-circuit conditions, both the inner and outer corners are key weak points that need to be strengthened.

[0112] For the two types of corners mentioned above, the present invention adopts the same local reinforcement structure design method: that is, at the inner corner of the low-voltage rectangular winding 11 and the outer corner of the high-voltage rectangular winding 12, corner-targeting reinforcement structures 3 with consistent structural forms and sizes adapted to their respective geometric curvatures are set. Specifically, each corner-targeting reinforcement structure 3 includes a first straight segment, a transition curve segment, and a second straight segment connected in sequence. The radius of curvature of the transition curve segment is strictly matched with the actual curvature of the corner it is attached to, the width is equal to the axial height of the corresponding winding, the arc length covers the entire bending area of ​​the corner, and the thickness parameters of the transition curve segment are independently determined through the mechanical analysis process of steps S31 to S35.

[0113] Although the inner and outer corners differ in spatial location and force direction (the inner corner mainly bears the inward radial compression tendency, while the outer corner mainly bears the outward radial expansion tendency), the circular arc curved beam mechanical model used in this invention treats radially distributed loads in absolute value form, and the glass fiber reinforced epoxy resin composite material has good bending and compressive strength. Therefore, the same design logic and calculation method can be used to determine the reinforced structural parameters of the inner and outer corners. Only the local maximum tangential contact stress value extracted from each simulation and the corresponding effective bearing length need to be calculated independently.

[0114] Thus, this invention achieves unified, efficient, and precise reinforcement of all high-stress corners in the rectangular winding 1 system, comprehensively improving the mechanical stability and insulation reliability of the overall winding structure of the amorphous alloy transformer under short-circuit conditions.

[0115] For example, during the fabrication of the corner-targeted reinforcement structure, a high-precision mold is used to shape the corner-targeted reinforcement structure to ensure that the radius of curvature, size, and shape of the corner-targeted reinforcement structure match the corner of the rectangular winding 1. The surface of the corner-targeted reinforcement structure is precision polished and deeply cleaned with anhydrous isopropanol to remove surface impurities, ensuring that it is in close contact with the surface of the rectangular winding 1.

[0116] During installation, the prefabricated corner-targeting reinforcement structure is placed at the corner between the outside of the high-voltage winding and the inside of the low-voltage winding. High-strength insulating epoxy structural adhesive is applied to the installation interface to ensure that the corner-targeting reinforcement structure and the copper conductor surface of the rectangular winding 1 are tightly bonded without gaps. A strict insulation distance is reserved between the outside of the rectangular winding 1 and the iron core or the inner wall of the tank.

[0117] Step S4: Determine the structural parameters of the long-side targeted reinforcement structure 3 used to fit the long side based on the stress distribution characteristics of the long side.

[0118] Furthermore, the long-side targeted reinforcement structure 3 includes a support plate extending along the long side of the rectangular winding 1. The design of this support plate considers the significant stress concentration problem in the middle of the long side of the rectangular winding 1 under short-circuit conditions, especially since the outer long side of the high-voltage winding bears a greater radial electrodynamic force, exhibiting a clear tendency for outward bulging deformation. To effectively suppress this deformation, the specific design of the support plate is as follows:

[0119] The support plate extends parallel to its long side along its length, with both ends extending to the adjacent corner-targeting reinforcement structure 3, ensuring effective coverage of the entire high-stress area. The width of the support plate is the same as the axial height of the rectangular winding 1, covering the long side along its axial height to ensure complete axial coverage and effective force transmission. The thickness of the support plate is perpendicular to the long side surface and points away from the rectangular winding 1, providing sufficient bending stiffness and support capacity. The structural parameters of the long-side-targeting reinforcement structure 3 include the thickness of the support plate.

[0120] In step S4, based on the stress distribution characteristics at the long side of the rectangular winding 1, the structural parameters of the long side targeted reinforcement structure 3 used to fit the long side are determined, especially the thickness of the support plate, to ensure that it can reliably support the winding under short-circuit conditions and avoid irreversible deformation or damage.

[0121] Step S4 specifically includes the following sub-steps:

[0122] Step S41: Based on the stress distribution characteristics of the rectangular winding 1 at the long side, extract the maximum radial electrodynamic force of the rectangular winding 1 on the surface of the long side.

[0123] Based on the stress distribution cloud map at the long side of the rectangular winding 1 obtained in step S1, the maximum radial electromotive force p at the middle of the long side of the high-voltage rectangular winding 12 is extracted. max (Unit: Pa) This value represents the maximum load acting on a unit area of ​​the support plate and is a key input for subsequent calculations.

[0124] Step S42: Based on the maximum radial electrodynamic force and the width of the support plate, determine the equivalent radial load intensity of the long side acting on the long side targeted reinforcement structure 3 on the width.

[0125] The distributed pressure p acting on the area covered by the support plate max Based on the static equivalence principle, it can be simplified to a uniformly distributed line load q acting on the support plate. steel The calculation formula is as follows:

[0126] ;

[0127] in, It is the width of the support plate.

[0128] Step S43: Simplify the long-side targeted reinforcement structure 3 into a straight beam model with a span of simply supported at both ends. The straight beam model bears the uniformly distributed radial pressure on the long side corresponding to the equivalent radial load intensity on the long side.

[0129] The support plate is simplified to a span of L. coverA straight beam model simply supported at both ends, which bears the aforementioned uniformly distributed wire load q. steel According to the theory of mechanics of materials, under uniformly distributed load, the bending moment at the mid-span section of this type of simply supported beam is the largest. The formula for calculating its design bending moment M is:

[0130] ;

[0131] Step S44: Based on the stress characteristics of the straight beam model under uniformly distributed radial pressure along its long side, calculate the second maximum bending moment borne by the straight beam model at the mid-span section; based on the above design bending moment M, check the bending strength of the support plate. The section modulus S2 of the rectangular cross-section of the support plate is S2 = b*t. -pad2 2 / 6, where t -pad2 This refers to the thickness of the support plate. The bending stress σ of the steel plate should satisfy:

[0132] ;

[0133] The allowable bending stress of the material used for the support plate.

[0134] Step S45: Determine the thickness of the support plate based on the second maximum bending moment and the allowable bending stress of the material used in the support plate.

[0135] ;

[0136] Furthermore, the support plate is constructed of sinusoidal corrugated steel. It should be noted that the yield strength of Q235 steel is 235 MPa. Considering factors such as manufacturing process, long-term operational reliability, and corrosion allowance, the thickness of the support plate should not be less than 2.0 mm in practical engineering applications.

[0137] For example, the support plate is constructed of sinusoidal corrugated steel plate. The load-displacement comparison curves of corrugated structural steel plates and flat steel plates of the same thickness are shown below. Figure 4As shown in the curve, the bending stiffness and deformation resistance of corrugated steel plates are significantly higher than those of ordinary low-carbon steel plates of the same thickness. Therefore, corrugated steel plates have a stronger ability to suppress the radial deformation of windings under short-circuit impact than ordinary flat steel plates. Since the design and calculation methods of sinusoidal corrugated steel plates are relatively simple, and CECS 290:2011 "Technical Specification for Application of Corrugated Web Steel Structures" has clearly given the design specifications and calculation methods for sinusoidal corrugated structures, the corrugated steel plate of the support layer in this embodiment adopts a sinusoidal corrugated shape design. According to CECS 290:2011, the sinusoidal corrugated amplitude is selected as 20mm and the single wave length is 150mm. The sinusoidal corrugated steel sheet is manufactured using CNC machining equipment. The machining process is completed collaboratively by various components, including a CNC system, a transmission system, a forming roller system, a pressure control system, and a measurement and feedback system. The CNC system receives input design parameters such as wavelength, amplitude, steel sheet thickness, and length, and generates precise operating commands to control each part of the equipment to move with high precision along a specified trajectory. The transmission system drives the forming rollers and robotic arm via servo motors and reducers, ensuring precise and controllable forming of the steel sheet. The forming roller system precisely controls the wavelength and amplitude by adjusting the roller angle and pressure. The pressure control system monitors pressure changes and adjusts the stress on the steel sheet during forming, ensuring the shape and thickness meet requirements. The measurement and feedback system measures parameters such as wavelength, amplitude, and thickness in real time and feeds the data back to the CNC system, dynamically adjusting the machining process to ensure the corrugated steel sheet meets design specifications.

[0138] like Figure 5 As shown, during installation, to eliminate the risk of hard contact between the metal support and the conductor of the rectangular winding 1, a four-layer array of high-temperature resistant silicone rubber elastic buffer pads is placed between the corrugated steel plate and the surface of the high-voltage winding. During installation, the four-layer array of high-temperature resistant silicone rubber elastic buffer pads is pre-compressed to provide initial preload. The two ends of the corrugated steel plate are reliably connected to the rigid metal clamps at the winding ends via high-strength epoxy resin supports 5 and high-strength bolts, ensuring that the support layer can effectively transfer loads during short circuits without loosening or shifting.

[0139] As can be seen from the technical solution, the embodiments provided by the present invention have the following advantages:

[0140] (1) The present invention obtains the mechanical response of rectangular winding 1 under short-circuit conditions through magnetic field-solid mechanical field coupling simulation model. Compared with traditional two-dimensional model and single physical field model, it can more accurately identify the mechanical response of rectangular winding 1 at the corner and long side, providing a reliable basis for strengthening structural design and avoiding blind strengthening.

[0141] (2) On this basis, for the two typical weak parts of the corner and the long side, a corner-targeted reinforcement structure 3 matching the stress state of the corner and a long-side-targeted reinforcement structure 3 matching the stress state of the long side are set up respectively, and their respective structural parameters are determined. Compared with the technical means of overall reinforcement or single local reinforcement of the support structure in related technologies, the structural parameters of the local reinforcement structure are designed based on the stress distribution under short-circuit conditions, which can effectively disperse local stress and suppress deformation, make up for the unresolved defects of local stress concentration in the previous support structure, and reduce the material waste caused by the overall reinforcement method.

[0142] Example 2

[0143] like Figure 6 As shown, a second aspect embodiment of the present invention provides a rectangular winding assembly 100, which includes a rectangular winding 1, a corner-targeted reinforcement structure 3, and a long-side-targeted reinforcement structure 3. The rectangular winding assembly 100 is structurally designed based on the aforementioned local reinforcement method, aiming to achieve systematic and high-reliability reinforcement of the key weak areas of the rectangular winding 1 of the amorphous alloy transformer under short-circuit conditions.

[0144] The rectangular winding assembly 100 includes a rectangular winding 1, a corner-targeting reinforcement structure 3, and a long-side-targeting reinforcement structure 3. The rectangular winding 1 is a square ring structure, including a pair of long sides with a length greater than the short side and a pair of short sides. Adjacent long sides and short sides are connected by a rounded corner. A low-voltage rectangular winding 11 and a high-voltage rectangular winding 12 are arranged sequentially from the inside to the outside along the radial direction of the winding itself. Correspondingly, the corners include an inner corner on the low-voltage rectangular winding 11 and an outer corner on the high-voltage rectangular winding 12.

[0145] The corner-targeting reinforcement structure 3 is located at each corner (including inner and outer corners), and its overall shape is L-shaped, including a first straight segment, a transition curve segment, and a second straight segment connected in sequence. The first straight segment is attached to the outer surface of one long side of the rectangular winding 1, the second straight segment is attached to the outer surface of the adjacent short side, and the transition curve segment is precisely attached to the corner between the long and short sides. The width of the transition curve segment is equal to the axial height of the rectangular winding 1 to fully cover the corner in the axial direction; its arc length matches the actual arc length of the winding corner to ensure a gapless fit in the arc extension direction; its thickness direction is perpendicular to the corner surface and points away from the rectangular winding 1 to effectively resist local deformation caused by short-circuit electromagnetic force.

[0146] It should be noted that the thickness of the transition curve segment here is determined based on the method in Implementation 1, while the thickness of the first straight line segment and the second straight line segment are the same as the thickness of the transition curve segment.

[0147] The long-side targeted reinforcement structure 3 includes a support plate extending along the long side of the rectangular winding 1. The length direction of the support plate is parallel to the long side, and its two ends extend to the adjacent corner targeted reinforcement structure 3 to cover the high-stress area in the middle of the long side identified by the S1 simulation. The width of the support plate is equal to the axial height of the rectangular winding 1, thereby achieving full height coverage in the axial direction. Its thickness direction is perpendicular to the surface of the long side and away from the winding to provide sufficient bending stiffness and suppress radial bulging deformation in the middle of the long side under short-circuit conditions.

[0148] In this embodiment, the support plate of the long-side targeted reinforcement structure extends along the outer side of the long side of the rectangular winding, with its length direction parallel to the long side. Both ends of the support plate extend to two adjacent corner targeted reinforcement structures in the length direction, but do not directly contact or connect with the corner targeted reinforcement structures. Specifically, the ends of the support plate and the ends of the first or second straight segments of the corresponding corner targeted reinforcement structure near the long side are substantially aligned in axial projection, with a small physical gap between them. This gap is used to avoid localized stress concentration caused by differences in thermal expansion or manufacturing tolerances, while ensuring that each reinforcement structure independently bears the load within its design area without interfering with each other.

[0149] In some examples, the length of the support plate can be 60% of the length of the longer side.

[0150] It should be noted that the thickness of the support plate here is determined based on one method, and the thickness of the support plate is the same in the length direction.

[0151] An epoxy structural adhesive layer is provided between the corner-targeted reinforcement structure 3 and the corresponding corner to achieve a high-strength, high-insulation bond between the two, ensuring effective load transfer and avoiding local electric field concentration.

[0152] The support plate is bolted to rigid metal clamps at the ends of the rectangular winding 1 at a preset torque T at both ends to ensure that the support structure does not loosen or shift during a short-circuit impact. The preset torque T is calculated using the following formula:

[0153]

[0154] Where k is the torque coefficient, which depends on the friction conditions of the threaded pair; f is the standard value of bolt preload; and d is the nominal diameter of the bolt. This torque control method ensures that the connection pair has a stable clamping force, balancing assembly reliability and structural safety.

[0155] In summary, the rectangular winding assembly 100 of this embodiment, by transforming the concept of partitioned targeted reinforcement based on multiphysics simulation into a specific structural integration scheme, achieves synergistic reinforcement of the corner and the middle of the long side, combining superior mechanical performance, reliable electrical insulation and engineering feasibility, and significantly improves the structural integrity and operational safety of the amorphous alloy transformer under short-circuit conditions.

[0156] For example, after the prefabrication of the corner-targeted reinforcement structure 3 and the long-side-targeted reinforcement structure 3 (i.e., the sinusoidal corrugated steel plate support layer) is completed, the assembly process of the rectangular winding 1, the corner-targeted reinforcement structure 3, and the long-side-targeted reinforcement structure 3 is as follows:

[0157] The corners of rectangular winding 1 and the middle of the long side of the high-voltage winding are pre-treated. Mechanical grinding is used to thoroughly remove the oxide layer, burrs, and other micro-defects from the conductor surface, ensuring the surface roughness Ra of the installation area is no greater than 6.3 μm. Subsequently, anhydrous isopropanol is used for deep cleaning of the treated area to completely remove oil, dust, and residual impurities, ensuring the bonding or fitting interface is clean and dry, providing a foundation for subsequent high-strength connections.

[0158] Based on the structural design drawings, a laser marking instrument was used to accurately mark the installation boundary of the corner-targeted reinforcement structure 3 at the winding corner. Simultaneously, the laying range of the sinusoidal corrugated steel plate support layer and the layout position of the four elastic buffer pads array were marked in the middle of the long side of the high voltage winding to ensure that the spatial positioning accuracy of each reinforcement component meets the design requirements.

[0159] A layer of highly insulating epoxy structural adhesive is uniformly coated on the contact surface between the corner-targeted reinforcement structure 3 and the winding corner; the corner-targeted reinforcement structure 3 is precisely aligned with the preset installation area along its curvature direction, and a controllable and uniform clamping force is applied and maintained until the adhesive is completely cured, thereby forming a high-strength, highly insulating rigid adhesive connection, ensuring that the corner-targeted reinforcement structure 3 and the winding are subjected to force together under short-circuit conditions without relative slippage.

[0160] In a designated area at the middle of the long side of the high-voltage winding, four elastic buffer pads made of high-temperature resistant silicone rubber are bonded at the designed spacing. The adhesive used has excellent thermal stability and electrical insulation properties. A special pressing device is used to apply constant pressure to the buffer pads to achieve an initial compression rate of 15% to provide a stable pre-tightening reaction force. After the adhesive has cured, a pre-fabricated sinusoidal corrugated steel plate is carefully attached to the surface of the buffer pad array, ensuring that its corrugation extension direction is strictly perpendicular to the winding axis to fully utilize its bending stiffness advantage and avoid stress eccentricity.

[0161] The sinusoidal corrugated steel plate is securely connected at both ends along its length to the rigid metal clamps at the ends of the rectangular winding 1 via pre-installed epoxy resin brackets 5 using high-strength bolts with a performance grade of not less than 8.8. During tightening, a calibrated torque wrench must be used to apply the preset torque strictly according to the bolt specifications and design requirements. This torque control measure ensures that the connection pair has sufficient clamping force and anti-loosening capability, maintaining structural integrity under short-circuit impact loads.

[0162] Through the aforementioned precision assembly process, this invention achieves high-precision and high-reliability integration of the corner-targeted reinforcement structure 3 and the long-side-targeted reinforcement structure 3 on the rectangular winding 1, effectively avoiding risks such as hard contact, local stress concentration, and loose connections, and providing structural protection for the safe and stable operation of amorphous alloy transformers under harsh short-circuit conditions. Assembly accuracy verification and functional determination;

[0163] After the overall assembly of the composite support structure is completed, precision checks and appropriate adjustments need to be made to its key stress-bearing components to ensure that the local reinforcement structure can fully exert its targeted reinforcement effect on the windings. Specifically:

[0164] Use measuring equipment to check the alignment accuracy and fitting gap between the corner-targeting reinforcement structure 3 and the corner. If the positional deviation between the two is large or there is a significant gap, the stress dispersion effect of the corner-targeting reinforcement structure 3 on the corner of the rectangular winding 1 will be greatly reduced, and readjustment is required.

[0165] Check whether the coverage area and corrugation shape of the sinusoidal corrugated steel plate meet the design requirements. If the coverage area of ​​the steel plate is insufficient, it will not be able to effectively suppress the bulging deformation in the middle of the long axis of the winding; if the corrugation shape of the steel plate is poor, it will affect its bending stiffness and load transfer efficiency.

[0166] Use a calibrated torque wrench to check the tightening torque of all bolts. Insufficient torque may cause the support structure to become unstable under short-circuit impacts, while excessive torque may damage components.

[0167] Example 3

[0168] like Figure 9 As shown, a third aspect embodiment of the present invention provides a method for verifying the effectiveness of a local reinforcement structure. Further, applied to the rectangular winding assembly 100 of a second aspect embodiment of the present invention, this verification method aims to quantitatively evaluate the mechanical response of the corner-targeted reinforcement structure 3 and the long-side-targeted reinforcement structure 3 under real working conditions through actual short-circuit impact tests, thereby scientifically determining whether its design is effective. The method comprises the following steps:

[0169] Obtain the first parameter characterizing the structural characteristics of the corner-targeted reinforcement structure 3 under actual short-circuit conditions, and the second parameter characterizing the structural characteristics of the long-side-targeted reinforcement structure 3 under actual short-circuit conditions;

[0170] The first parameter is compared with the first preset threshold. If the first parameter does not exceed the first preset threshold, the corner-targeted reinforcement structure 3 is determined to be effective.

[0171] The second parameter is compared with the second preset threshold. If the second parameter does not exceed the second preset threshold, the long-side targeted enhancement structure 3 is determined to be effective.

[0172] The first parameter is the stress value measured at the transition curve segment of the corner-targeted reinforcement structure 3 under short-circuit conditions; the first preset threshold is the allowable stress of the material used in the corner-targeted reinforcement structure 3 divided by the safety factor; the second parameter includes the stress value measured by the support plate under actual short-circuit conditions, and the radial displacement value of the middle of the long side of the rectangular winding 1; the second preset threshold includes: the allowable stress of the material used in the support plate divided by the safety factor, and the maximum radial displacement of the long side of the rectangular winding 1 under short-circuit conditions determined by the magnetic field-solid mechanics field coupling simulation model.

[0173] like Figures 6-9 As shown, specifically, firstly, in a professional transformer short-circuit test station conforming to the national standard GB / T 1094.5–2008 "Power Transformers Part 5: Short-Circuit Withstand Capacity", a standard short-circuit impact test was conducted on an amorphous alloy transformer prototype equipped with a composite support structure. Before the test, high-precision sensing devices were arranged at key measuring points: piezoelectric strain sensors were installed at the geometric center of the outer surface of the corner-targeted reinforcement structure 3 (denoted as measuring point P1) and the geometric center of the outer surface of the long-side targeted reinforcement structure 3 (denoted as measuring point P2), respectively. At the same time, a laser displacement sensor with an accuracy of 0.01 mm was installed at the corresponding position in the middle of the long axis of the high-voltage winding (denoted as measuring point P3) to monitor radial dynamic deformation in real time.

[0174] During the short-circuit impact, the above sensors simultaneously collect the following parameters:

[0175] The actual stress value borne by the corner-targeted reinforcement structure 3 (Measured by sensor at P1);

[0176] The actual stress value borne by the long-side targeted reinforcement structure 3 (Measured by the sensor at P2);

[0177] The maximum radial dynamic displacement δ at the middle of the long axis of the high voltage winding (measured by the sensor at P3).

[0178] Then, the first parameter obtained (i.e. ) is compared with the first preset threshold, if If the value does not exceed this threshold, the corner-targeted reinforcement structure 3 is deemed effective.

[0179] At the same time, the second parameter (including δ) are compared with the corresponding second preset thresholds respectively. If neither of them exceeds their respective thresholds, the long-side targeted enhancement structure 3 is determined to be effective.

[0180] This verification method achieves closed-loop verification of the functional performance of locally reinforced structures through a three-step logic of "actual measurement - criterion - judgment", ensuring that they have the expected load-bearing capacity and deformation suppression effect under real short-circuit conditions.

[0181] The first preset threshold is defined as the allowable bending stress [σ] of the material used in the corner-targeted reinforcement structure 3 (i.e., glass fiber reinforced epoxy resin composite material). pad Divide by the safety factor K S ,Right now:

[0182] First preset threshold = ;

[0183] Among them, [σ pad K was obtained through material mechanical property testing. S This is the engineering safety factor, which is usually taken as 1.5.

[0184] The second parameter includes two items:

[0185] (1) The stress value measured at measuring point P2 of the support plate (i.e., sinusoidal corrugated steel plate) under actual short-circuit conditions. ;

[0186] (2) The radial displacement value δ of the middle of the long side of the rectangular winding 1 at the measuring point P3.

[0187] Correspondingly, the second preset threshold also includes two items:

[0188] (1) The yield strength [σy] of the material used for the support plate (Q235 steel) is 235MPa divided by the same safety factor KS, i.e. ;

[0189] (2) The maximum radial displacement of the long side of the rectangular winding 1 under short-circuit conditions, predicted by the magnetic field-solid mechanics field coupling simulation model established in step S1. .

[0190] The validity criteria are as follows:

[0191] If both conditions are met , , ;

[0192] The locally reinforced structural design is considered to have passed the effectiveness verification. This verification system not only considers the strength safety margin of the reinforced components themselves, but also introduces a displacement benchmark based on multiphysics simulation, realizing a comprehensive evaluation mechanism integrating "material strength, structural stiffness, and simulation prediction", which significantly improves the scientificity and reliability of the verification results.

[0193] It should be emphasized that the present invention has the following advantages:

[0194] (1) By constructing a three-dimensional magnetic-structure coupling simulation model of an amorphous alloy transformer, this invention can more accurately identify the stress concentration characteristics at the corner of the rectangular winding 1 and the middle of the long axis compared with the traditional two-dimensional model and single physical field model, providing a reliable basis for strengthening structural design and avoiding blind strengthening.

[0195] (2) This invention abandons the traditional approach of overall reinforcement or single local strengthening of the support structure, and innovatively proposes a "zone-targeted" strengthening strategy. At the weak corner of the rectangular winding 1, an L-shaped glass fiber reinforced epoxy resin composite pad matching the corner curvature is used; in the weak area at the center of the long axis, a sinusoidal corrugated steel plate support layer with better bending strength is used. The composite structure of these two components achieves precise strengthening of the high-stress area of ​​the winding. This not only compensates for the unresolved defect of local stress concentration in previous support structures, but also avoids the material waste caused by the overall reinforcement method, achieving precise and efficient strengthening of the short-circuit resistance of the rectangular winding 1.

[0196] (3) The composite support structure of the present invention is a proprietary design that is highly adapted to the special mechanical properties of the rectangular winding 1. In this structural design, the curvature of the L-shaped pad matches the winding angle, avoiding the stress concentration risk caused by right-angle support and effectively dispersing the angle stress. The corrugated structure of the sinusoidal corrugated steel plate can effectively absorb and disperse impact energy through elastic deformation, and has better bending strength than ordinary steel plates of equal thickness. The high compatibility of the support structure with the rectangular winding 1 in terms of geometry and mechanical properties significantly improves its reliability under short-circuit impact and can effectively reduce the risk of deformation of the rectangular winding 1 under short-circuit conditions.

[0197] Other configurations and operations of the rectangular winding 1 according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here. In the description of the present invention, "first feature" and "second feature" may include one or more of the features. The up-down direction, left-right direction, and front-back direction are defined as shown in the figures.

[0198] In the description of this invention, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features not in direct contact but through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature.

[0199] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0200] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for designing a locally reinforced rectangular winding structure, wherein the rectangular winding includes a pair of long sides and a pair of short sides, adjacent long sides and short sides are connected by a corner, and the length of the long side is greater than the length of the short side, characterized in that, It includes the following steps: Step S1: Obtain the mechanical response of the rectangular winding under short-circuit conditions using a magnetic field-solid mechanics field coupling simulation model; Step S2: Based on the mechanical response, obtain the stress distribution characteristics of the rectangular winding at the corner and on the long side; Step S3: Determine the structural parameters of the corner-targeting reinforcement structure used to fit the corner based on the stress distribution characteristics of the corner; Step S4: Determine the structural parameters of the long-side targeted reinforcement structure used to fit the long side based on the stress distribution characteristics of the long side.

2. The rectangular winding local reinforcement structure design method according to claim 1, characterized in that, The corner-targeting reinforcement structure includes a first straight segment, a transition curve segment, and a second straight segment connected in sequence. The first straight segment and the second straight segment are used to fit the adjacent long side and short side of the rectangular winding, respectively. The transition curve segment is used to fit the corner of the rectangular winding between the adjacent long side and short side. The width of the transition curve segment is equal to the axial height of the rectangular winding to cover the corner at the axial height of the rectangular winding, and the arc length of the transition curve segment matches the arc length of the corner to cover the corner in the arc extension direction of the corner. The thickness direction of the transition curve segment is perpendicular to the corner surface and points away from the rectangular winding. In step S3, the structural parameters of the corner-targeted reinforcement structure include the thickness of the transition curve segment.

3. The rectangular winding local reinforcement structure design method according to claim 2, characterized in that, Step S3 specifically includes the following sub-steps: Step S31: Based on the stress distribution characteristics of the rectangular winding at the corner, extract the maximum tangential contact stress value of the surface of the rectangular winding at the corner; Step S32: Based on the maximum tangential contact stress value and the effective bearing length of the rectangular winding in the radial direction at the corner, determine the equivalent radial load intensity of the corner-targeted reinforcement structure per unit axial height; Step S33: Simplify the transition curve segment of the corner-targeted reinforcement structure into a circular arc beam model with fixed supports at both ends. The radius of curvature of the circular arc beam model is the same as that of the transition curve segment, and it bears the uniformly distributed radial pressure at the corner corresponding to the equivalent radial load intensity at the corner. Step S34: Based on the stress characteristics of the circular arc beam model under uniformly distributed radial pressure at the rotation angle, calculate the first maximum bending moment borne by the circular arc beam model at the constrained end; Step S35: Based on the first maximum bending moment and the allowable bending stress of the material used in the corner-targeted reinforcement structure, calculate the thickness of the transition curve segment in the radial direction.

4. The rectangular winding local reinforcement structure design method according to claim 2, characterized in that, The corner-targeted reinforcement structure is constructed from glass fiber reinforced epoxy resin composite material.

5. The rectangular winding local reinforcement structure design method according to claim 1, characterized in that, The long-side targeted reinforcement structure includes a support plate extending along the long side of the rectangular winding; The length direction of the support plate is parallel to the long side, and both ends of the support plate in the length direction extend to the adjacent corner-targeting reinforcement structure. The width of the support plate is the same as the axial height of the rectangular winding to cover the long side in the axial height of the rectangular winding. The thickness direction of the support plate is perpendicular to the surface of the long side and points away from the rectangular winding. In step S4, the structural parameters of the long-side targeted reinforcement structure include the thickness of the support plate.

6. The rectangular winding local reinforcement structure design method according to claim 5, characterized in that, Step S4 specifically includes the following sub-steps: Step S41: Based on the stress distribution characteristics of the rectangular winding at the long side, extract the maximum radial electrodynamic force of the rectangular winding on the surface of the long side; Step S42: Based on the maximum radial electrodynamic force and the width of the support plate, determine the equivalent radial load intensity of the long side acting on the long side targeted reinforcement structure. Step S43: Simplify the long-side targeted reinforcement structure into a straight beam model with a span of simply supported at both ends. The straight beam model bears the uniformly distributed radial pressure on the long side corresponding to the equivalent radial load intensity on the long side. Step S44: Based on the stress characteristics of the straight beam model under uniformly distributed radial pressure along its long side, calculate the second maximum bending moment borne by the straight beam model at the mid-span section. Step S45: Determine the thickness of the support plate based on the second maximum bending moment and the allowable bending stress of the material used in the support plate.

7. The rectangular winding local reinforcement structure design method according to claim 6, characterized in that, The support plate is constructed of sinusoidal corrugated steel.

8. A rectangular winding assembly, characterized in that, include: A rectangular winding includes a pair of long sides and a pair of short sides, with adjacent long and short sides connected by a corner, and the length of the long side is greater than the length of the short side; The corner-targeting reinforcement structure includes a first straight segment, a transition curve segment, and a second straight segment connected in sequence. The first straight segment and the second straight segment are respectively used to fit the adjacent long side and short side of the rectangular winding, and the transition curve segment is used to fit the corner of the rectangular winding between the adjacent long side and short side. The long-side targeted reinforcement structure includes a support plate extending along the long side of the rectangular winding, with both ends of the support plate extending to the adjacent corner targeted reinforcement structure. An epoxy adhesive layer is provided between the corner-targeted reinforcement structure and the corner. The two ends of the support plate in the length direction are fixed to the rigid metal clamps on the rectangular winding by bolts with a preset torque T. The formula for calculating the preset torque T is: ； in, The torque coefficient, This refers to the standard value of bolt preload. This refers to the nominal diameter of the bolt.

9. A method for verifying the effectiveness of a locally reinforced structure, characterized in that, The rectangular winding assembly applied in claim 8 comprises the following steps: Obtain the first parameter characterizing the structural characteristics of the corner-targeted reinforcement structure under actual short-circuit conditions, and the second parameter characterizing the structural characteristics of the long-side-targeted reinforcement structure under actual short-circuit conditions; The first parameter is compared with the first preset threshold. If the first parameter does not exceed the first preset threshold, the corner-targeted reinforcement structure is determined to be effective. The second parameter is compared with the second preset threshold. If the second parameter does not exceed the second preset threshold, the long-side targeted reinforcement structure is determined to be effective.

10. The method for verifying the effectiveness of the locally reinforced structure according to claim 9, characterized in that, The first parameter is the stress value measured at the transition curve segment of the corner-targeted reinforcement structure under short-circuit conditions; The first preset threshold is the allowable stress of the material used in the corner-targeted reinforcement structure divided by the safety factor; The second parameter includes the stress value measured by the support plate under actual short-circuit conditions, and the radial displacement value of the middle of the long side of the rectangular winding. The second preset threshold includes: the allowable stress of the material used in the support plate divided by the safety factor, and the maximum radial displacement of the long side of the rectangular winding under short-circuit conditions determined by the magnetic field-solid mechanics field coupling simulation model.

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