Method and system for evaluating structural strength of transformer for wind power, and medium

Abstract

The invention provides a method, medium and system for evaluating the structural strength of a transformer for wind power, which are applied to the field of transformers for wind power, and the method comprises the following steps: S1, determining the basic condition of the transformer structure; s2, acquiring corresponding material mechanical property parameters; s3, establishing a transformer structure model; s4, determining a calculation load of the structure according to design specification requirements; s5, performing strength calculation on the structural model of the transformer; s6, obtaining a structural strength analysis chart of the transformer; and S7, establishing an analysis logic process of the structural strength, and deciding whether redesign is needed or not and further design verification to complete the comprehensive evaluation of the structural strength. Through comparative analysis of calculation results of the structure under various loads and material mechanical properties of the structure and modal calculation result analysis, an analysis logic process of the structural strength is established, and a rapid judgment decision of the structural strength integrity is supported; multiple tests of physical prototypes are avoided, cost is reduced, and efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power transformers, and in particular to a method, medium and system for evaluating the structural strength of a wind power transformer. Background Art

[0002] Wind power generation converts wind energy into electrical energy, and wind power transformers are crucial distribution equipment within wind power systems. Wind power transformers require special consideration for their unique operating environments and demanding operating conditions. The core challenge lies in ensuring the transformer's structural integrity during long-term vibration, mechanical shock, and long-distance transportation, thereby ensuring reliable operation of the entire wind turbine.

[0003] Currently, the structural strength assessment of wind power transformers is mostly conducted by manufacturing physical prototypes and placing them on a vibration table for vibration and impact tests. Durability tests under vibration conditions require even longer tests, with some lasting over 24 hours. Each test is costly in terms of both financial, human, and time expenditures. Summary of the Invention

[0004] In order to overcome the above technical defects, the present invention provides a method, medium and system for evaluating the structural strength of a wind power transformer, which can solve the problem of how to evaluate the structural strength of a wind power transformer.

[0005] The present invention is implemented according to the following technical solutions: A first aspect of the present invention provides a method for evaluating the structural strength of a wind power transformer, comprising: S1: Determine basic conditions of the transformer structure, including structural materials; S2: According to the structural material of the transformer in S1, obtain the corresponding material mechanical performance parameters; S3: Based on the basic situation of the transformer in S1, a transformer structure model is established; S4: Determine the calculated loads of the structure according to the design specifications, which include transportation load, hoisting load, operation load and fatigue load; S5: Using finite element software, perform strength calculation on the transformer structure model according to the pre-processing of strength calculation defined in S2, S3 and S4; S6: Using the post-processing module of the finite element software, obtain the structural strength analysis diagram of the transformer and obtain the equivalent stress, maximum principal stress, strain, relative displacement, and natural frequency of the supporting components of the transformer mechanical system. Among them, in the calculation results of the load condition of S5, the equivalent stress is used to determine whether the structural material will yield due to the load; the combination of maximum principal stress and strain is used to determine whether plastic deformation and fracture failure occur in the area of ​​local stress concentration; relative displacement is used to check whether there is motion interference between components; and natural frequency is used to determine whether the structure resonates due to coincidence with the external excitation frequency. S7: Establish a logical analysis process for structural strength, make decisions on whether redesign is needed and the next step of design verification, and complete a comprehensive assessment of structural strength.

[0006] Compared with the existing technology, the structural strength evaluation method of the wind power transformer of the present application establishes a logical analysis process of structural strength by comparing the calculation results of the structure under various loads with the material mechanical properties of the structure, as well as analyzing the modal calculation results, to support the rapid evaluation and decision-making of the structural strength integrity; among them, the logical analysis process of structural strength continuously optimizes the model of the wind power transformer through three dimensions (structural yield strength, fatigue characteristics, and dynamic characteristics) to obtain the preferred option of the structural design scheme; avoids multiple rectification and testing of physical prototypes, which leads to high product R&D costs, low testing efficiency and long development cycles.

[0007] In one embodiment, in S1, the basic conditions of the transformer structure include the size of the mechanical system support components, the assembly relationship between the components, and the installation and fixation type of the transformer; wherein the mechanical system support components include an iron core, a coil, an insulating part, and a steel structure; and the installation and fixation type includes bolted connections and welded parts.

[0008] In one embodiment, in S2, the material mechanical performance parameters include elastic modulus, Poisson's ratio, yield strength, tensile strength, and material fatigue life curve.

[0009] In one embodiment, in S3, a corresponding modeling method and a boundary condition processing method of a simulated installation and fixing type are selected according to the basic conditions of the transformer structure to establish a transformer structure model.

[0010] In one embodiment, in S4, the calculated load is determined according to one of the following three situations: Case 1 is when there is actual test data. The transportation load and hoisting load are measured by installing a three-dimensional impact recorder at the designated monitoring point of the transformer to monitor the transportation and hoisting acceleration data as the input for the calculation load; For operating loads and fatigue loads, vibration acceleration sensors are placed at key locations where wind turbines connect to transformers in wind farms to collect acceleration time domain information, which is then converted to the frequency domain using fast Fourier transform to ultimately obtain the power density spectrum. Case 2 is when there is a design load but no test data. In preliminary design or less complex situations, a comprehensive load factor is used. To amplify the actual working load design value , and thus use the static strength method for approximate verification; according to the formula , and based on the recommended value of the load factor Determine the calculated load ;in, : Calculation load of the superposition of static additional force and dynamic additional force; : actual working load design value; Case 3 is to determine the transportation conditions and select the corresponding calculation load according to the relevant requirements of domestic and international wind turbine design specifications. The calculation load also includes the acceleration response spectrum (frequency-acceleration curve, time-acceleration curve) or power density spectrum (frequency-power density).

[0011] In one embodiment, the pre-processing of S5 includes importing the model, meshing to generate quadrilateral or hexahedral meshes, defining material properties, defining boundary conditions (fixed constraints) and load types (gravity, dynamic force, acceleration, etc.).

[0012] In one embodiment, after the pre-processing is completed in S5, a calculation method is selected according to the corresponding load condition, specifically including: S51: Transient calculation of transport loads using random vibration with power density spectrum or acceleration response spectrum; S52: The hoisting load is calculated by static superposition of gravity and hoisting inertia force; S53: Random vibration, harmonic response analysis, and response spectrum analysis of operating loads using power density spectrum; S54: Extreme loads are calculated using the sine beat frequency method; S55: Structural dynamic characteristics are calculated using modal calculations. Structural dynamic characteristics refer to the intrinsic properties of a structure in response to dynamic forces, including natural frequency, mode shape, and damping.

[0013] In one embodiment, the step S7 establishes a logical flow of analyzing the structural strength, specifically including: S71: Using the material mechanical properties parameters of the structure in S2, the various calculated loads determined in S4, and the structural strength analysis diagram obtained in S6 as key decision points, establish a structural strength analysis logic flow chart; and perform an assessment based on the structural strength analysis logic flow chart. S72: According to the wind turbine design requirements in the standard, select the corresponding load safety factor under different load conditions , material safety factor and failure safety factor ; S73: Evaluate the equivalent stress of structures , Equivalent stress: , in: The minimum yield strength specified for hot-rolled structural steel in EN10025-2 European standard; is the safety factor of failure; is the safety factor of the material; Yield safety reserve factor: , If the yield reserve safety factor , then turn to structural strength design verification; If the yield reserve safety factor , then turn to evaluate the local stress-strain and use the Neuber law factor; Neuber's Law: , in: is the maximum principal stress; is Young's modulus; If the Neuber law factor , then turn to structural strength design verification; If the Neuber law factor , then turn to redesign; S74: Evaluate damage to structures under combined loads, calculating damage based on maximum principal stress , damage:

[0014] in: is the number of cycles applied; is the fatigue life; is the material parameter; is the fatigue life and the critical fatigue combined stress range; is the slope of the SN curve; Fatigue reserve safety factor

[0015] in: The damage occurs in the critical stress range.

[0016] If the fatigue reserve safety factor , then turn to structural strength design verification; If the fatigue reserve safety factor If not, go to redesign; S75: Evaluate the first order natural frequency of the structure, and perform modal calculation by using finite element software, and analyze to determine the dynamic characteristics of the structure; If the first order natural frequency in the modal calculation result is greater than or equal to 5Hz, go to structural strength design verification; If the first order natural frequency in the modal calculation result is less than 5Hz, go to redesign.

[0017] The second aspect of the present application provides a computer readable storage medium, the computer readable storage medium has program instructions stored therein, the program instructions are used to execute the wind power transformer structural strength evaluation method described above when running.

[0018] The third aspect of the present application provides a wind power transformer structural strength evaluation system, the system comprises one or more processors, the one or more processors are used to call and run the instructions stored in the memory, so that the wind power transformer structural strength evaluation method described above is executed.

[0019] In order to better understand and implement, the present application is described in detail below in conjunction with the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0020] The specific embodiments of the present application are further described in detail below in conjunction with the drawings, wherein: Figure 1 It is a perspective view of the wind power transformer of the present application; Figure 2 It is a flowchart of the wind power transformer structural strength evaluation method of the present application; Figure 3 It is a material fatigue life curve of the present application; Figure 4 It is a transport load lateral axis power density spectrum of the present application; Figure 5 It is a transport load vertical axis power density spectrum of the present application. DETAILED DESCRIPTION

[0021] The preferred embodiments of the present application are described below in conjunction with the drawings, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0022] In order to better illustrate the present application, the present application is further described in detail below with reference to the drawings.

[0023] It should be clear that the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the embodiments of the present application.

[0024] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the embodiments of the present application. The singular forms "a," "the," and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0025] When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims. In the description of the present application, it should be understood that the terms "first", "second", "third", etc. are only used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence, nor can they be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0026] In this application, unless otherwise specified, "plurality" refers to two or more. "And / or" describes a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0027] Structural reference for wind power transformers (hereinafter referred to as transformers) Figure 1As shown, the transformer includes an iron core 1, an upper clamp 2, a pull plate 3, a winding 4, a spacer 5, a lower clamp 6 and a base 7, and the base 7 is installed on the connecting plate corresponding to the wind power nacelle. For wind power transformers, due to the environmental influences they are subject to, they will be subjected to periodic mechanical shocks, so their structural strength needs to be fully considered during design and production. The structural strength of the transformer is mainly assessed by the following parameters: structural strength under long-term loads (such as operating loads, fatigue loads), and structural strength under transient loads (such as transportation shocks, lifting loads), to ensure the long-term reliability of the transformer. The wind power transformer is installed in the nacelle, and the impact of continuous fatigue caused by the self-vibration of the head during operation needs to be considered. In addition, the fatigue damage caused by the maximum principal stress of the wind power transformer structure and the first-order natural frequency are precisely the key factors in the durability and avoidance of resonance in the design of wind turbines.

[0028] In order to solve the above problems, the first aspect of the present invention provides a method for evaluating the structural strength of a wind power transformer, such as Figure 2 As shown, it includes: S1: Determine the basic situation of the transformer structure; S2: According to the structural material of the transformer in S1, obtain the corresponding material mechanical performance parameters; S3: Based on the basic situation of the transformer in S1, a transformer structure model is established; S4: Determine the calculated loads of the structure according to the design specifications, which include transportation load, hoisting load, operation load and fatigue load; S5: Perform strength calculation on the transformer structural model using finite element software according to the pre-processing of strength calculation defined in S2, S3, and S4. The finite element software is ANSYS, a large-scale general-purpose finite element analysis (FEA) software developed by ANSYS Corporation of the United States. It is the fastest-growing computer-aided engineering (CAE) software in the world and can interface with most computer-aided design software to achieve data sharing and exchange, such as Creo, NASTRAN, Algor, I-DEAS, AutoCAD, etc.

[0029] S6: Using the post-processing module of the finite element software, obtain the structural strength analysis diagram of the transformer and obtain the equivalent stress, maximum principal stress, strain, relative displacement, and natural frequency of the supporting components of the transformer mechanical system. Among them, in the calculation results of the load condition of S5, the equivalent stress is used to determine whether the structural material will yield due to the load; the combination of maximum principal stress and strain is used to determine whether plastic deformation and fracture failure occur in the area of ​​local stress concentration; relative displacement is used to check whether there is motion interference between components; and natural frequency is used to determine whether the structure resonates due to coincidence with the external excitation frequency. S7: Establish the analysis logic flow of structural strength, make decisions on whether to redesign and proceed to the next step of design verification, and complete the comprehensive evaluation of structural strength.

[0030] Compared with the prior art, the evaluation method of the structural strength of the transformer for wind power disclosed in the application, by comparing and analyzing the calculation results of the structure under various loads with the material mechanics performance of the structure, and analyzing the modal calculation results, establishes the analysis logic flow of structural strength to support the rapid evaluation and decision-making of the structural strength integrity; wherein the analysis logic flow of structural strength continuously optimizes the model of the transformer for wind power through three dimensions (structural yield strength, fatigue characteristics, and dynamic characteristics) to obtain the preferred option of the structural design scheme; avoids multiple modifications and tests of the physical prototype, and solves the problems of high product development cost, low test efficiency, and long development cycle.

[0031] The specific implementation of the above steps is described in detail as follows: In this embodiment, in S1, the basic conditions of the transformer structure include the size of the mechanical system support components, the assembly relationship between the components, and the installation and fixing type of the transformer; wherein the mechanical system support components include the core, the coil, the insulation part, and the steel structure part; and the installation and fixing type includes the bolt connection and the welding position. The above S1 fully understands the basic conditions of the transformer structure, which lays a foundation for the smooth progress of the subsequent steps.

[0032] In this embodiment, in S2, the material mechanics performance parameters include the elastic modulus, the Poisson's ratio, the yield strength, the tensile strength, and the material fatigue life curve. Specifically, according to the Machinery Manual and the EN10025-2 European standard hot-rolled structural steel, the material mechanics performance parameters corresponding to the structural material of the transformer in S1 are consulted, such as the density, the elastic modulus, the Poisson's ratio, and the yield strength of the corresponding material and other parameters; in this embodiment, the key structural material of the transformer for wind power is Q355 structural steel, the elastic modulus is 210 GPa, the Poisson's ratio is 0.3, the yield strength is 355 MPa, and the tensile strength is 470 MPa. According to the EN-1993-1-9 European standard steel structure design, the fatigue life curve diagram is obtained as shown in Figure 3 For other materials, the above method can also be used to query the material mechanics performance parameters.

[0033] In this embodiment, in S3, according to the basic conditions of the transformer structure, the corresponding modeling method and the boundary condition processing method of the simulated installation and fixing type are selected to establish the transformer structure model. Specifically, entity elements can be used for modeling, the end surface of the transformer base and the cabin connecting plate is fixedly constrained, and the modeling software (such as Creo modeling software) is used to establish the transformer structure model corresponding to the transformer for wind power in S1, as shown in Figure 1 As shown, the transformer includes a core 1 in a square frame structure, an upper clamp 2 in a 250 slot steel structure, a pull plate 3 in an 8*120 flat steel structure, a winding 4 in a cylindrical structure, a cushion block 5 in a square block structure, a lower clamp 6 in a 320 slot steel structure, and a base 7 in a 25mm thick steel plate structure.

[0034] In this embodiment, in S4, the calculation load is determined according to one of the following three cases, Case 1 is the case of having test measured data, Transportation load and hoisting load: by installing a three-dimensional impact recorder at the designated monitoring point of the transformer, monitoring the transportation acceleration data and hoisting acceleration data, as input data for calculating the load.

[0035] Running load and fatigue load: by arranging vibration acceleration sensors at the key positions of the wind turbine and the transformer connection in the wind farm, collecting acceleration time domain information, and using fast Fourier transform to convert it to the frequency domain, the power density spectrum is finally obtained.

[0036] Specifically, the output of the three-dimensional impact recorder and the vibration acceleration sensor is the acceleration-time curve. Among them, the horizontal axis of the curve is time (s), and the vertical axis is acceleration (g or m / s 2 ).

[0037] The pre-processing method of the above raw data includes removing the mean value to eliminate the influence of gravity and other static acceleration, and using a window function (Hanning window) to reduce the frequency spectrum leakage caused by signal stages.

[0038] After preprocessing the data, the recorded “time-acceleration” is directly converted into “frequency-acceleration” curve by using fast Fourier transform.

[0039] Table 1: “Frequency-acceleration” curve characteristic parameter table converted from the output of the three-dimensional impact recorder and the vibration acceleration sensor

[0040] Based on the power density spectrum The conversion formula converts the acceleration response spectrum into the power density spectrum.

[0041]

[0042] Wherein: is the frequency (Hz); is the damping ratio (usually 0.05, i.e. 5%). Acceleration amplitude (m / s2) for corresponding frequency According to the above formula, the following table 2 is converted: Table 2 Power density spectrum

[0043] Case 2 is the case of having design load but no experimental data, in the preliminary design or not too complex occasion, using a comprehensive load coefficient To amplify the actual working load design value , so as to use static strength method to approximate check; according to the formula , and according to the recommended value of load coefficient To determine the calculation load ; wherein : the calculation load of the superposition of static additional force and dynamic additional force; : the actual working load design value; Specifically, according to the recommended value of load coefficient selected from Machinery Manual , such as Transport load: =1.6; hoisting load: =1.2~1.5; running load: =1.0~1.1; fatigue load: =1.0~1.1.

[0044] Assuming that the actual working load design value is obtained by mechanical analysis: Transport load design value: ; Hoisting load design value: ; Running load design value: ; Fatigue load design value: , (positive sign indicates tension, so that the part is tensioned); , (negative sign indicates pressure, so that the part is pressed).

[0045] According to the above formula, we get: Transport calculation load:

[0046] Hoisting calculation load: , (take the middle value ) Running calculation load: , (take the middle value ) Fatigue calculation load: , (take the middle value ) , (take the middle value ) It should be noted that the calculation load mentioned above According to its specific load conditions (Transport calculation load), (Calculation load for hoisting), (Run calculation load), (Fatigue calculation load); similarly, the recommended value of the load factor and actual working load design value So too.

[0047] Case 3 is to obtain the calculated load according to the relevant requirements of domestic and foreign wind turbine design specifications. The calculated load also includes the acceleration response spectrum and power density spectrum. According to the standard GJB150.16, the transportation condition is determined to be road transportation using a two-wheel trailer. The lateral axis power density spectrum is obtained from the standard as follows: Figure 4 As shown, the vertical axis power density spectrum is as follows Figure 5 shown.

[0048] Among them, GJB 150.16 "Vibration Test for Environmental Test Methods of Military Equipment" is used to evaluate the vibration resistance of equipment in its expected transportation and use environment, and is issued by the Commission of Science, Technology and Industry for National Defense.

[0049] In this embodiment, the pre-processing of S5 includes importing the model, meshing to generate quadrilateral or hexahedral meshes, defining material properties, defining boundary conditions (fixed constraints) and load types (gravity, dynamic force, acceleration, etc.).

[0050] In this embodiment, after the pre-processing is completed in S5, a calculation method is selected according to the corresponding load condition, specifically including: S51: Transient calculation of transport loads using random vibration with power density spectrum or acceleration response spectrum; S52: The hoisting load is calculated by static superposition of gravity and hoisting inertia force; S53: Random vibration, harmonic response analysis, and response spectrum analysis of operating loads using power density spectrum; S54: Extreme loads are calculated using the sine beat frequency method; S55: Modal calculations are used to calculate the structural dynamic characteristics. These characteristics refer to the inherent properties of a structure's response to dynamic forces. These characteristics include natural frequencies, mode shapes, and damping. Modal calculations are used to extract these natural frequencies and mode shapes.

[0051] In this embodiment, the step S6 obtains a structural strength analysis diagram of the transformer, and obtains equivalent stress, maximum principal stress, strain, relative displacement, and natural frequency results of supporting components of the transformer mechanical system, as shown in Table 3.

[0052] Table 3 Stress calculation results under load conditions

[0053] Table 4 Modal calculation results

[0054] In this embodiment, the S7 establishes a logical flow of structural strength analysis, specifically including: S71: Using the material mechanical properties parameters of the structure in S2, the various calculated loads determined in S4, and the structural strength analysis diagram obtained in S6 as key decision points, establish a structural strength analysis logic flow chart; and perform an evaluation based on the structural strength analysis logic flow chart. S72: According to the relevant provisions of the wind turbine design requirements in the foreign standard IEC61400-1 and the domestic standard GB18451.1, select the corresponding load safety factor under different load conditions , material safety factor and failure safety factor ; For example, in this embodiment, the load condition is selected to select various safety factors of the transport load.

[0055] Table 5 Safety factors for various load conditions

[0056] S73: Evaluate the equivalent stress of structures , which mainly evaluates the paradigm equivalent stress of materials; Equivalent stress: , in: The minimum yield strength specified for hot-rolled structural steel in EN10025-2 European standard; is the safety factor of failure; is the safety factor of the material; Yield safety reserve factor: , If the yield reserve safety factor , then turn to structural strength design verification; If the yield reserve safety factor , we turn to evaluating local stress-strain and use the Neuber law factor.

[0057] Neuber's Law: It should be noted that Neuber's law is often used to calculate the damage degree and fatigue life of materials under different working conditions, especially under complex stress states, such as compression, torsion and other non-axisymmetric stress states.

[0058] in: is the maximum principal stress; is Young's modulus.

[0059] If the Neuber law factor , then turn to structural strength design verification; If the Neuber law factor , then turn to redesign; According to the above formula and the material mechanical properties parameters of S2, if we want to , then the corresponding equivalent stress of the material should not exceed 322MPa. In addition, if the local stress of the structure exceeds the yield stress of the material, the Neuber law should be used for verification. If the product passes, the process moves on to structural strength design verification. Otherwise, the product fails and requires redesign. The Young's modulus of the transformer's key structural material is 210 GPa. According to the above formula, for the product to pass, the corresponding maximum principal stress should not exceed 823 MPa.

[0060] S74: Evaluate damage to structures under combined loads, calculating damage based on maximum principal stress . Mainly evaluate the load conditions of transportation, lifting and operation; damage:

[0061] in: is the number of cycles applied; is the fatigue life; is the material parameter; is the fatigue life and the critical combined fatigue stress range; is the slope of the SN curve.

[0062] Fatigue reserve safety factor

[0063] in: The damage occurs in the critical stress range.

[0064] If the fatigue reserve safety factor , then turn to structural strength design verification; If the fatigue reserve safety factor In this embodiment, according to the above formula and the mechanical properties parameters of S2 material, if we want to For structural steel, Figure 3As shown in EN-1993-1-9 European Standard for Design of Steel Structures, Life and Fatigue Critical Combined Stress Range , the corresponding fatigue stress should not exceed 93.5MPa.

[0065] Table 6 Failure criteria for load conditions

[0066] S75: Evaluate the first-order natural frequency of the structure and perform modal calculations using finite element software to analyze and determine the dynamic characteristics of the structure; If the first-order natural frequency in the modal calculation results is ≥5Hz, then proceed to structural strength design verification; If the first-order natural frequency in the modal calculation results is less than 5Hz, then redesign.

[0067] It should be noted that the analysis should include a sufficient number of modes to obtain a combined modal mass participation of more than 90% of the structural mass, that is, the total modal mass participation in the horizontal and vertical directions is at least 90% of the actual mass, so that the results of the modal calculation are of reference value.

[0068] Table 7 Criteria for modal calculation results

[0069] Based on the structural strength analysis diagram of S6, the strength analysis diagrams of all load conditions (transportation, hoisting, and operation) are obtained, as well as the material mechanical performance parameters of S2. Combined with the strength analysis logic process of S7, decisions are made on whether redesign is needed and the next step of design verification, completing a comprehensive assessment of structural strength.

[0070] Based on the established logical flow for structural strength analysis, this embodiment calculates the maximum stress value and first-order natural frequency of the wind power transformer structure under transport load conditions. The analysis results show that the stress values ​​under the yield failure criterion, local stress failure criterion, and fatigue failure criterion, as well as the first-order natural frequency of the modal, are all lower than the corresponding criterion requirements. In summary, the structural strength meets the relevant regulations and can proceed to the next step of design verification. At this point, the key decision-making for the structural strength assessment of the wind power transformer has been completed.

[0071] A second aspect of the present invention provides a computer-readable storage medium having program instructions stored therein. When the program instructions are executed, the program instructions are used to execute the above-mentioned method for evaluating the structural strength of a wind power transformer.

[0072] The third aspect of the present invention provides a system for evaluating the structural strength of a wind power transformer, the system comprising one or more processors, the one or more processors being used to call and run instructions stored in a memory from the memory so that the above-mentioned method for evaluating the structural strength of a wind power transformer is executed.

[0073] Based on the disclosure and teachings of the above description, those skilled in the art may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and modifications and variations of the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although certain specific terms are used in this description, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A method for evaluating the structural strength of a wind power transformer, characterized in that: include: S1: Determine basic conditions of the transformer structure, including structural materials; S2: According to the structural material of the transformer in S1, obtain the corresponding material mechanical performance parameters; S3: Based on the basic situation of the transformer in S1, a transformer structure model is established; S4: Determine the calculated loads of the structure according to the design specifications, which include transportation load, hoisting load, operation load and fatigue load; S5: Using finite element software, perform strength calculation on the transformer structure model according to the pre-processing of strength calculation defined in S2, S3 and S4; S6: Using the post-processing module of the finite element software, obtain the structural strength analysis diagram of the transformer and obtain the equivalent stress, maximum principal stress, strain, relative displacement, and natural frequency of the supporting components of the transformer mechanical system. Among them, in the calculation results of the load condition of S5, the equivalent stress is used to determine whether the structural material will yield due to the load; the combination of maximum principal stress and strain is used to determine whether plastic deformation and fracture failure occur in the area of ​​local stress concentration; relative displacement is used to check whether there is motion interference between components; and natural frequency is used to determine whether the structure resonates due to coincidence with the external excitation frequency. S7: Establish a logical analysis process for structural strength, make decisions on whether redesign is needed and the next step of design verification, and complete a comprehensive assessment of structural strength.

2. The method for evaluating the structural strength of a wind power transformer according to claim 1, wherein: In S1, the basic information of the transformer structure also includes the size of the mechanical system support components, the assembly relationship between the components, and the installation and fixation type of the transformer; wherein the mechanical system support components include the iron core, coils, insulation parts and steel structures; the installation and fixation type includes bolt connection and welding parts.

3. The method for evaluating the structural strength of a wind power transformer according to claim 1, wherein: In S2, the material mechanical performance parameters include elastic modulus, Poisson's ratio, yield strength, tensile strength and material fatigue life curve.

4. The method for evaluating the structural strength of a wind power transformer according to claim 1, wherein: In S3, according to the basic situation of the transformer structure, the corresponding modeling method and the boundary condition processing method of the simulated installation and fixation type are selected to establish the transformer structure model.

5. The method for evaluating the structural strength of a wind power transformer according to claim 1, wherein: In S4, the calculated load is determined according to one of the following three cases, Case 1 is when there is actual test data. For transport and hoisting loads, three-dimensional impact recorders are installed at designated monitoring points on the transformer to monitor transport and hoisting acceleration data, which serve as input for load calculation. For operational and fatigue loads, vibration acceleration sensors are placed at key locations connecting the wind turbine and transformer in the wind farm to collect acceleration time domain information. Fast Fourier transform is used to convert this information into the frequency domain, ultimately yielding a power density spectrum. Case 2 is when there is a design load but no test data. In preliminary design or less complex situations, a comprehensive load factor is used. To amplify the actual working load design value , and thus use the static strength method for approximate verification; according to the formula , and based on the recommended value of the load factor Determine the calculated load ;in, : Calculation load of the superposition of static additional force and dynamic additional force; : actual working load design value; Case 3 is to determine the transportation conditions and select the corresponding calculation load according to the relevant requirements of domestic and foreign wind turbine design specifications. The calculation load also includes the acceleration response spectrum and power density spectrum.

6. The method for evaluating the structural strength of a wind power transformer according to claim 1, wherein: The S5 pre-processing includes importing the model, meshing to generate quadrilateral or hexahedral meshes, defining material properties, and defining boundary conditions and load types.

7. The method for evaluating the structural strength of a wind power transformer according to claim 1, wherein: After the pre-processing is completed in S5, a calculation method is selected according to the corresponding load condition, specifically including: S51: Transient calculation of transport loads using random vibration with power density spectrum or acceleration response spectrum; S52: The hoisting load is calculated by static superposition of gravity and hoisting inertia force; S53: Random vibration, harmonic response analysis, and response spectrum analysis of operating loads using power density spectrum; S54: Extreme loads are calculated using the sine beat frequency method; S55: Structural dynamic characteristics are calculated using modal calculations. Structural dynamic characteristics refer to the intrinsic properties of a structure in response to dynamic forces, including natural frequency, mode shape, and damping.

8. The method for evaluating the structural strength of a wind power transformer according to claim 1, wherein: The S7 establishes a logical flow of structural strength analysis, specifically including: S71: Using the material mechanical properties parameters of the structure in S2, the various calculated loads determined in S4, and the structural strength analysis diagram obtained in S6 as key decision points, establish a structural strength analysis logic flow chart; and perform an assessment based on the structural strength analysis logic flow chart. S72: According to the wind turbine design requirements in the standard, select the corresponding load safety factor under different load conditions , material safety factor and failure safety factor ; S73: Evaluate the equivalent stress of structures , Equivalent stress: , in: The minimum yield strength specified for hot-rolled structural steel in EN10025-2 European standard; is the safety factor of failure; is the safety factor of the material; Yield safety reserve factor: , If the yield reserve safety factor , then turn to structural strength design verification; If the yield reserve safety factor , then turn to evaluate the local stress-strain and use the Neuber law factor; Neuber's Law: , in: is the maximum principal stress; is Young's modulus; If the Neuber law factor , then turn to structural strength design verification; If the Neuber law factor , then turn to redesign; S74: Evaluate damage to structures under combined loads, calculating damage based on maximum principal stress , damage: in: is the number of cycles applied; is fatigue life; is the material parameter; is the fatigue life and the critical fatigue combined stress range; is the slope of the SN curve; Fatigue reserve safety factor in: Damage caused by critical stress range; If the fatigue reserve safety factor , then turn to structural strength design verification; If the fatigue reserve safety factor , then turn to redesign; S75: Evaluate the first-order natural frequency of the structure and perform modal calculations using finite element software to analyze and determine the dynamic characteristics of the structure; If the first-order natural frequency in the modal calculation results is ≥5Hz, then proceed to structural strength design verification; If the first-order natural frequency in the modal calculation results is less than 5Hz, then redesign.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores program instructions, and when the program instructions are executed, they are used to execute the method for evaluating the structural strength of a wind power transformer according to any one of claims 1 to 8.

10. A system for evaluating the structural strength of a wind power transformer, characterized in that: The system comprises one or more processors, wherein the one or more processors are used to call and run instructions stored in a memory, so that the method for evaluating the structural strength of a wind power transformer according to any one of claims 1 to 8 is executed.

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