A method, medium and system for evaluating structural strength of a transformer for wind power

Abstract

The application provides a kind of wind power transformer structural strength evaluation method, medium and system, apply in wind power transformer field, method includes: S1 determine the basic situation of transformer structure;S2 obtain corresponding material mechanics performance parameter;S3 establish transformer structure model;S4 according to design specification requirement, determine the calculation load of structure;S5 the strength calculation of transformer structure model;S6 obtain the structural strength analysis diagram of transformer;S7 establish the analysis logic flow of structural strength, decision whether to need redesign, and carry out next step design verification, complete the comprehensive evaluation of structural strength.Comparison and analysis are made by comparing the calculation results of structure under various loads with the material mechanics performance of structure, modal calculation result analysis, the analysis logic flow of structural strength is established, which supports the rapid judgment and decision of structural strength integrity;Avoid multiple tests of physical prototype, reduce cost and improve efficiency.

Description

Technical Field

[0001] This invention relates to the technical field of wind power transformers, and particularly to a method, medium, and system for evaluating the structural strength of wind power transformers. Background Technology

[0002] Wind power generation is a method of converting wind energy into electrical energy, and wind power transformers are important power distribution equipment in wind power generation systems. Special considerations must be given to the unique operating environment and stringent working conditions of wind power transformers. The core challenge lies in ensuring that the transformer maintains its structural integrity during long-term vibration, mechanical shock, and long-distance transportation, thereby guaranteeing the reliable operation of the entire wind turbine unit.

[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 vibration testing requires even longer testing times, with some tests lasting over 24 hours. Each test incurs significant costs in terms of finances, manpower, and time. Summary of the Invention

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

[0005] This invention is implemented according to the following technical solution:

[0006] A first aspect of the present invention provides a method for evaluating the structural strength of a wind power transformer, comprising:

[0007] S1: Determine the basic structural information of the transformer, including the structural materials;

[0008] S2: Based on the structural materials of the transformer in S1, obtain the corresponding material mechanical property parameters;

[0009] S3: Based on the basic information about the transformer in S1, establish a transformer structural model;

[0010] S4: Determine the calculated loads of the structure according to the design specifications. The calculated loads include transportation loads, hoisting loads, running loads, and fatigue loads.

[0011] S5: Using finite element software, based on the preprocessing defined in S2, S3 and S4 for strength calculation, the structural model of the transformer is subjected to strength calculation;

[0012] 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's mechanical system. Among them, in the calculation results of the load condition in 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 occurs in the local stress concentration area, leading to fracture failure; relative displacement is used to check whether there is motion interference between components; natural frequency is used to determine whether the structure resonates due to the coincidence of the excitation frequency with the external environment.

[0013] S7: Establish a logical process for analyzing structural strength, make decisions on whether redesign is needed and on further design verification, and complete a comprehensive assessment of structural strength.

[0014] Compared with existing technologies, the structural strength evaluation method for wind power transformers in this application establishes a logical flow for structural strength analysis by comparing and analyzing 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. This supports rapid judgment and decision-making on the integrity of structural strength. The logical flow for structural strength analysis 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 structural design scheme. This avoids the problems of high product development costs, low testing efficiency, and long development cycles caused by multiple modifications and tests of physical prototypes.

[0015] In one embodiment, in S1, the basic information about the transformer structure includes the dimensions of the mechanical system support components, the assembly relationship between the components, and the type of installation and fixing of the transformer; wherein, the mechanical system support components include the core, coils, insulating parts, and steel structural parts; and the type of installation and fixing includes bolted connections and welded parts.

[0016] In one embodiment, in S2, the material mechanical property parameters include elastic modulus, Poisson's ratio, yield strength, tensile strength, and material fatigue life curve.

[0017] In one embodiment, in S3, based on the basic characteristics of the transformer structure, an appropriate modeling method and a boundary condition handling method for simulating fixed installation types are selected to establish a transformer structure model.

[0018] In one embodiment, in S4, the calculated load is determined based on one of the following three conditions:

[0019] Case 1 involves having experimentally measured data. The transport load and hoisting load are calculated by installing a three-dimensional impact recorder at a designated monitoring point on the transformer to monitor the acceleration data of the transport and hoisting, which is then used as input for load calculation.

[0020] Operating load and fatigue load are obtained by placing vibration acceleration sensors at key locations where the wind turbine and transformer are connected in the wind farm to collect acceleration time-domain information, and then using fast Fourier transform to convert it to the frequency domain, finally obtaining the power density spectrum.

[0021] Case 2 involves situations where there is a design load but no experimental data. In preliminary designs or less complex applications, a comprehensive load factor is used. To amplify the design value of the actual working load Therefore, an approximate verification is performed using the static strength method; according to the formula And based on the recommended value of the load factor. Determine the calculation load ;in, : The calculated load is the superposition of static and dynamic additional forces; Actual working load design value;

[0022] Case 3 involves determining the corresponding calculation load based on the relevant requirements of domestic and international wind turbine design specifications, taking into account transportation conditions. The calculation load also includes acceleration response spectrum (frequency-acceleration curve, time-acceleration curve) or power density spectrum (frequency-power density).

[0023] In one embodiment, the preprocessing of S5 includes importing the model, generating a quadrilateral or hexahedral mesh, defining material properties, defining boundary conditions (fixed constraints), and defining load types (gravity, dynamic force, acceleration, etc.).

[0024] In one embodiment, after S5 completes the preprocessing, a calculation method is selected according to the corresponding load condition, specifically including:

[0025] S51: The transport load is calculated using the transient method of random vibration or acceleration response spectrum of power density spectrum;

[0026] S52: The lifting load is calculated by static superposition of gravity and lifting inertia force;

[0027] S53: The operating load is analyzed using random vibration, harmonic response, and response spectrum analysis based on power density spectrum.

[0028] S54: Extreme loads are calculated using the sinusoidal beat frequency method;

[0029] S55: The structural dynamic characteristics are calculated using modal analysis; whereby the structural dynamic characteristics refer to the inherent properties of the structure in response to dynamic forces, including natural frequencies, mode shapes, and damping.

[0030] In one embodiment, step S7 establishes the analysis logic flow for structural strength, specifically including:

[0031] S71: Using the material mechanical properties 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 flowchart; conduct an evaluation based on the structural strength analysis logic flowchart;

[0032] S72: Select the appropriate load safety factor under different load conditions according to the wind turbine generator design requirements in the standard. Material safety factor and failure safety factor ;

[0033] S73: Evaluate the equivalent stress of the structure ,

[0034] Equivalent stress: ,

[0035] in: The minimum yield strength specified for hot-rolled structural steel according to the European standard EN10025-2; The safety factor for failure; The safety factor of the material;

[0036] Yield safety reserve factor: ,

[0037] If the yield reserve safety factor Then, the focus shifts to structural strength design verification;

[0038] If the yield reserve safety factor Then, the evaluation shifts to assessing local stress-strain, using Neuberger's rule factor;

[0039] Neuber's Law: ,

[0040] in: This is the maximum principal stress; Young's modulus;

[0041] If Neuberger's rule factor Then, the focus shifts to structural strength design verification;

[0042] If Neuberger's rule factor Then it's time to redesign;

[0043] S74: Evaluate the damage to the structure under combined loads, and calculate the damage based on the maximum principal stress. ,

[0044] damage:

[0045] in: The number of cycles applied; For fatigue life; Material parameters; This refers to the range of fatigue life and critical combined fatigue stress. The slope of the SN curve;

[0046] Fatigue reserve safety factor

[0047] in: Damage generated within the critical stress range.

[0048] If fatigue reserve safety factor Then, the focus shifts to structural strength design verification;

[0049] If fatigue reserve safety factor Then it's time to redesign;

[0050] S75: Evaluate the first natural frequency of the structure, perform modal calculations using finite element software, and analyze to determine the dynamic characteristics of the structure;

[0051] If the first natural frequency in the modal calculation results is ≥5Hz, then the structural strength design verification for steering is required.

[0052] If the first natural frequency in the modal calculation results is less than 5Hz, then a redesign should be initiated.

[0053] A second aspect of the present invention provides a computer-readable storage medium storing program instructions that, when executed, perform the above-described method for evaluating the structural strength of a wind power transformer.

[0054] A 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 configured to call and execute instructions stored in a memory, thereby executing the aforementioned method for evaluating the structural strength of a wind power transformer.

[0055] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0056] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein:

[0057] Figure 1 This is a perspective view of the wind power transformer of the present invention;

[0058] Figure 2 This is a flowchart illustrating the method for evaluating the structural strength of wind power transformers according to the present invention.

[0059] Figure 3 This is a fatigue life curve of the material in this invention;

[0060] Figure 4 This is the power density spectrum of the transport load transverse axis of the present invention;

[0061] Figure 5 This is the power density spectrum of the transport load vertical axis of the present invention. Detailed Implementation

[0062] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0063] To better illustrate the present invention, the invention will now be described in further detail with reference to the accompanying drawings.

[0064] It should be understood that the described embodiments are merely some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of the embodiments of this application.

[0065] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0066] In the following description, when referring 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 this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0067] Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0068] Structural reference for wind power transformers (hereinafter referred to as transformers) Figure 1 As shown, the transformer includes a core 1, an upper clamp 2, a tie plate 3, windings 4, pads 5, a lower clamp 6, and a base 7. The base 7 is installed on the corresponding connection plate of the wind turbine nacelle. For wind turbine transformers, due to environmental influences, they are subject to periodic mechanical shocks, requiring careful consideration of structural strength during design and manufacturing. The structural strength of the transformer is mainly assessed by the following parameters: structural strength under long-term loads (e.g., operating loads, fatigue loads) and structural strength under instantaneous loads (e.g., transportation impacts, lifting loads), ensuring the long-term reliability of the transformer. Since the wind turbine transformer is installed inside the nacelle, the continuous fatigue caused by the vibration of the turbine head during operation must be carefully considered. Furthermore, the fatigue damage caused by the maximum principal stress and the first natural frequency of the wind turbine structure are precisely the key durability and resonance avoidance factors in wind turbine design.

[0069] To address the aforementioned problems, a 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:

[0070] S1: Determine the basic structural details of the transformer;

[0071] S2: Based on the structural materials of the transformer in S1, obtain the corresponding material mechanical property parameters;

[0072] S3: Based on the basic information about the transformer in S1, establish a transformer structural model;

[0073] S4: Determine the calculated loads of the structure according to the design specifications. The calculated loads include transportation loads, hoisting loads, running loads, and fatigue loads.

[0074] S5: Using finite element software, based on the preprocessing defined in S2, S3, and S4, strength calculations are performed on the structural model of the transformer. The finite element software used is ANSYS, a large-scale general-purpose finite element analysis (FEA) software developed by ANSYS Inc. in 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.

[0075] 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's mechanical system. Among them, in the calculation results of the load condition in 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 occurs in the local stress concentration area, leading to fracture failure; relative displacement is used to check whether there is motion interference between components; natural frequency is used to determine whether the structure resonates due to the coincidence of the excitation frequency with the external environment.

[0076] S7: Establish a logical process for analyzing structural strength, make decisions on whether redesign is needed and on further design verification, and complete a comprehensive assessment of structural strength.

[0077] Compared with existing technologies, the structural strength evaluation method for wind power transformers in this application establishes a logical flow for structural strength analysis by comparing and analyzing 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. This supports rapid judgment and decision-making on the integrity of structural strength. The logical flow for structural strength analysis 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 structural design scheme. This avoids the problems of high product development costs, low testing efficiency, and long development cycles caused by multiple modifications and tests of physical prototypes.

[0078] The specific implementation methods of the above steps are described in detail below:

[0079] In this embodiment, in S1, the basic information about the transformer structure includes the dimensions of the mechanical system support components, the assembly relationships between the parts, and the type of installation and fixing of the transformer. The mechanical system support components include the core, coils, insulation components, and steel structural components. The type of installation and fixing includes bolted connections and welded joints. A thorough understanding of the basic information about the transformer structure through S1 lays the foundation for the smooth progress of subsequent steps.

[0080] In this embodiment, in S2, the material mechanical property parameters include elastic modulus, Poisson's ratio, yield strength, tensile strength, and material fatigue life curve. Specifically, according to the mechanical handbook and the EN10025-2 European standard for hot-rolled structural steel, the material mechanical property parameters corresponding to the transformer structural material in S1 are consulted, such as the density, elastic modulus, Poisson's ratio, and yield strength of the corresponding material. In this embodiment, the key structural material of the wind power transformer is Q355 structural steel, with an elastic modulus of 210 GPa, a Poisson's ratio of 0.3, a yield strength of 355 MPa, and a tensile strength of 470 MPa. According to the EN-1993-1-9 European standard for steel structural component design, the fatigue life curve is obtained as follows: Figure 3 As shown. For other materials, the same method can be used to look up their material mechanical properties.

[0081] In this embodiment, in S3, based on the basic characteristics of the transformer structure, an appropriate modeling method and boundary condition handling method for simulating installation and fixing are selected to establish a transformer structure model. Specifically, solid elements can be used for modeling, with fixed constraints applied to the end faces of the transformer base and the nacelle connection plate. Modeling software (such as Creo) is used to establish a transformer structure model corresponding to the wind power transformer in S1, such as... Figure 1 As shown, the transformer includes an iron core 1, which adopts a square frame structure; an upper clamping member 2, which adopts a 250-gauge channel steel structure; a tie plate 3, which adopts an 8*120 flat steel structure; a winding 4, which adopts a cylindrical structure; a pad 5, which adopts a square block structure; a lower clamping member 6, which adopts a 320-gauge channel steel structure; and a base 7, which adopts a 25mm thick steel plate structure. The base 7 is installed on the corresponding connecting plate of the wind turbine nacelle.

[0082] In this embodiment, in S4, the calculated load is determined based on one of the following three conditions:

[0083] Scenario 1 is when experimental measurement data is available.

[0084] Transportation load and hoisting load: By installing three-dimensional impact recorders at designated monitoring points on the transformer, transportation acceleration data and hoisting acceleration data are monitored and used as input data for load calculation.

[0085] Operating load and fatigue load: Vibration acceleration sensors are placed at key locations connecting the wind turbine and transformer in the wind farm to collect acceleration time-domain information, which is then converted to the frequency domain using fast Fourier transform to obtain the power density spectrum.

[0086] Specifically, the raw data output by the 3D impact recorder and vibration acceleration sensor is a curve showing the change in acceleration over time. The horizontal axis of this curve represents time (s), and the vertical axis represents acceleration (g or m / s²).2 ).

[0087] The preprocessing of the raw data includes removing the mean to eliminate the effects of static accelerations such as gravity, and using a window function (Hanning window) to reduce spectral leakage caused by signal stages.

[0088] The preprocessed data is then transformed directly into a frequency-acceleration curve using the Fast Fourier Transform.

[0089] Table 1. Characteristic parameters of the "frequency-acceleration" curve converted from the raw data output by the 3D impact recorder and vibration acceleration sensor.

[0090]

[0091] Based on power density spectrum The conversion formula transforms the acceleration response spectrum into a power density spectrum.

[0092]

[0093] in:

[0094] Frequency (Hz);

[0095] The damping ratio is typically taken as 0.05, or 5%.

[0096] This represents the acceleration amplitude (m / s²) at the corresponding frequency.

[0097] The above formulas are converted as shown in Table 2 below:

[0098] Table 2 Power Density Spectrum

[0099]

[0100] Case 2 involves situations where there is a design load but no experimental data. In preliminary designs or less complex applications, a comprehensive load factor is used. To amplify the design value of the actual working load Therefore, an approximate verification is performed using the static strength method; according to the formula And based on the recommended value of the load factor. Determine the calculation load ;in, : The calculated load is the superposition of static and dynamic additional forces; Actual working load design value;

[0101] Specifically, the recommended value for the load factor should be selected based on the mechanical handbook. ,like

[0102] Transport load: =1.6; Lifting load: =1.2~1.5; Operating load: =1.0~1.1; Fatigue load: =1.0~1.1.

[0103] Assuming that the design value of the actual working load is obtained through mechanical analysis:

[0104] Design values ​​for transport load: ;

[0105] Design value of lifting load: ;

[0106] Operating load design values: ;

[0107] Fatigue load design values: (The plus sign indicates tension, causing the part to be under tension);

[0108] (The negative sign indicates pressure, which puts pressure on the part).

[0109] Based on the above formula, we can derive:

[0110] Transportation calculation load:

[0111] Calculated load for hoisting: (take the middle value) )

[0112] Run the calculation load: (take the middle value) )

[0113] Fatigue calculation load: (take the middle value) )

[0114] (take the middle value) )

[0115] It should be noted that the computational load mentioned above... It will be based on its specific load conditions. (Transportation calculation load) (Lifting calculation load) (Running calculation load) The load is represented in the manner of (fatigue calculation load); similarly, the recommended value of the load factor... and actual working load design value That is also true.

[0116] Scenario 3 involves obtaining the calculated loads based on relevant requirements of domestic and international wind turbine design specifications. These calculated loads include the acceleration response spectrum and power density spectrum. According to standard GJB150.16, the transportation conditions are determined to be road transport using a two-wheeled trailer. The transverse 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 As shown.

[0117] Among them, GJB 150.16 "Environmental Test Methods for Military Equipment - Vibration Test" is used to evaluate the vibration resistance of equipment in its intended transportation and use environment, and is issued by the Commission of Science, Technology and Industry for National Defense.

[0118] In this embodiment, the preprocessing of S5 includes importing the model, generating quadrilateral or hexahedral meshes, defining material properties, defining boundary conditions (fixed constraints) and load types (gravity, dynamic force, acceleration, etc.).

[0119] In this embodiment, after S5 completes the preprocessing, a calculation method is selected according to the corresponding load condition, specifically including:

[0120] S51: The transport load is calculated using the transient method of random vibration or acceleration response spectrum of power density spectrum;

[0121] S52: The lifting load is calculated by static superposition of gravity and lifting inertia force;

[0122] S53: The operating load is analyzed using random vibration, harmonic response, and response spectrum analysis based on power density spectrum.

[0123] S54: Extreme loads are calculated using the sinusoidal beat frequency method;

[0124] S55: The structural dynamic characteristics are calculated using modal analysis; whereby structural dynamic characteristics refer to the intrinsic properties of a structure in response to dynamic forces, including natural frequencies, mode shapes, and damping. The purpose of modal analysis is to extract these natural frequencies and mode shapes.

[0125] In this embodiment, step S6 obtains the structural strength analysis diagram of the transformer and obtains the equivalent stress, maximum principal stress, strain, relative displacement and natural frequency results of the supporting components of the transformer mechanical system, as shown in Table 3.

[0126] Table 3 Stress calculation results under load conditions

[0127]

[0128] Table 4 Modal calculation results

[0129]

[0130] In this embodiment, step S7 establishes the analysis logic flow for structural strength, specifically including:

[0131] S71: Using the material mechanical properties 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 flowchart; perform evaluation based on the structural strength analysis logic flowchart;

[0132] S72: In accordance with the relevant provisions of international standard IEC61400-1 and domestic standard GB18451.1 regarding the design requirements of wind turbine generator sets, 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 based on the various safety factors of the transport load.

[0133] Table 5 Safety Factors for Various Load Conditions

[0134]

[0135] S73: Evaluate the equivalent stress of the structure The main assessment focuses on the paradigm equivalence stress of materials.

[0136] Equivalent stress: ,

[0137] in: The minimum yield strength specified for hot-rolled structural steel according to the European standard EN10025-2; The safety factor for failure; The safety factor of the material;

[0138] Yield safety reserve factor: ,

[0139] If the yield reserve safety factor Then, the focus shifts to structural strength design verification;

[0140] If the yield reserve safety factor Then, the evaluation shifts to assessing local stress-strain, using the Neuberger rule factor.

[0141] Neuber's Law: It should be noted that Neuber's rule is often used to calculate the degree of damage and fatigue life of materials under different working conditions, especially under complex stress states, such as non-axisymmetric stress states such as compression and torsion.

[0142] in: This is the maximum principal stress; It is Young's modulus.

[0143] If Neuberger's rule factor Then, the focus shifts to structural strength design verification;

[0144] If Neuberger's rule factor Then it's time to redesign;

[0145] Based on the above formula and the material mechanical property parameters of S2, if we want to make If the equivalent stress of the material exceeds 322 MPa, then the equivalent stress should not exceed 322 MPa. Furthermore, if the local stress of the structure exceeds the yield stress of the material, the Neuberger rule should be used for verification. When the product structure... If the product passes the initial test, the process moves to structural strength design verification; otherwise, the product fails and requires redesign. The Young's modulus of the key structural material for the transformer is 210 GPa. According to the above formula, for the product to pass the test, the maximum principal stress corresponding to the material should not exceed 823 MPa.

[0146] S74: Evaluate the damage to the structure under combined loads, and calculate the damage based on the maximum principal stress. The main assessment focuses on the load conditions during transportation, hoisting, and operation.

[0147] damage:

[0148] in: The number of cycles applied; For fatigue life; Material parameters; denoted as fatigue life and the range of critical combined fatigue stress; denoted as the slope of the SN curve.

[0149] Fatigue reserve safety factor

[0150] in: Damage generated within the critical stress range.

[0151] If fatigue reserve safety factor Then, the focus shifts to structural strength design verification;

[0152] If fatigue reserve safety factor Therefore, a redesign is necessary. In this embodiment, based on the above formula and the mechanical property parameters of material S2, if it is to make... For structural steel, such as Figure 3 As shown, EN-1993-1-9 European standard specifies the design, life, and critical combined stress range for steel structural members. The corresponding fatigue stress should not exceed 93.5 MPa.

[0153] Table 6 Failure Criteria for Load Conditions

[0154]

[0155] S75: Evaluate the first natural frequency of the structure, perform modal calculations using finite element software, and analyze to determine the dynamic characteristics of the structure;

[0156] If the first natural frequency in the modal calculation results is ≥5Hz, then the structural strength design verification for steering is required.

[0157] If the first natural frequency in the modal calculation results is less than 5Hz, then a redesign should be initiated.

[0158] It should be noted that the analysis should include a sufficient number of modes to obtain more than 90% of the combined modal mass of the structure. That is, the total modal mass participation in the horizontal and vertical directions should be at least 90% of the actual mass. Only then will the results of the modal calculation be reliable.

[0159] Table 7 Criteria for Modal Calculation Results

[0160]

[0161] Based on the structural strength analysis diagram of S6, strength analysis diagrams for all load conditions (transportation, hoisting, and operation) are obtained, along with the material mechanical property parameters of S2. Combining the strength analysis logic flow of S7, decisions are made on whether redesign is needed and on further design verification, thus completing a comprehensive assessment of structural strength.

[0162] Based on the established structural strength analysis logic, this embodiment calculates the maximum stress value and the first natural frequency of the wind power transformer structure under transportation 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 natural frequency of the modes, are all lower than the corresponding criterion requirements. In summary, the structural strength meets the relevant regulatory requirements and can proceed to the next design verification stage. This completes the key decision for assessing the structural strength of the wind power transformer.

[0163] A second aspect of the present invention provides a computer-readable storage medium storing program instructions that, when executed, perform the above-described method for evaluating the structural strength of a wind power transformer.

[0164] A 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 configured to call and execute instructions stored in a memory, thereby executing the aforementioned method for evaluating the structural strength of a wind power transformer.

[0165] Based on the disclosure and teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. A method of evaluating structural strength of a transformer for wind power, characterized by, Comprise: S1: determine the basic situation of transformer structure, the basic situation includes structure material; S2: according to the structure material of transformer in S1, the corresponding material mechanical property parameter is obtained; S3: according to the basic situation of transformer in S1, the transformer structure model is established; S4: according to the design specification requirement, the calculation load of structure is determined, the calculation load includes transportation load, hoisting load, operation load and fatigue load; In S4, the calculation load is determined according to one of the following three conditions, Case 1 is that there is test measured data, the transportation load and the hoisting load are monitored through the installation of three-dimensional impact recorder at the specified monitoring point of transformer, the transportation and hoisting acceleration data are monitored as the input of calculation load; the operation load and the fatigue load are collected through the arrangement of vibration acceleration sensor at the key position of wind turbine and transformer connection in wind farm, the time domain information is converted to frequency domain by using fast Fourier transform, and finally the power density spectrum is obtained; Case 2 is the case of having design load but no measured data, in the preliminary design or less complex occasions, using a comprehensive load coefficient to amplify the actual working load design value , so as to use static strength method for approximate checking; 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;​ Case 3 is that according to the relevant requirements of domestic and foreign wind turbine design specification, the corresponding calculation load is selected according to the transportation condition, the calculation load also includes acceleration response spectrum and power density spectrum; S5: using finite element software, according to the pretreatment of strength calculation defined by S2, S3 and S4, the strength calculation of transformer structure model is carried out; S6: using the post-processing module of finite element software, the structure strength analysis diagram of transformer is obtained, the equivalent stress, maximum principal stress, strain, relative displacement and natural frequency of mechanical system supporting components of transformer are obtained; wherein, in the calculation result of load working condition of S5, the equivalent stress is used to judge whether the structure material will yield and fail due to load; the combination of maximum principal stress and strain is used to judge whether the local stress concentration area will occur plastic deformation and lead to fracture damage; the relative displacement is used to check whether there is movement interference between components; the natural frequency is used to judge whether the structure will resonate due to the coincidence with the excitation frequency of external environment; S7: establish the analysis logic flow of structure strength, make decision on whether to redesign and carry out next step design verification, and complete the comprehensive evaluation of structure strength.

2. The evaluation method of transformer structure strength for wind power according to claim 1, wherein: in S1, the basic situation of transformer structure further includes the size of mechanical system supporting components, the assembly relationship between components, and the installation and fixing type of transformer; wherein, the mechanical system supporting components include core, coil, insulation and steel structure; the installation and fixing type includes bolt connection and welding position.

3. The evaluation method of transformer structure strength for wind power according to claim 1, wherein: in S2, the material mechanical property parameter includes elastic modulus, Poisson's ratio, yield strength, tensile strength and material fatigue life curve.

4. The evaluation method of transformer structure strength for wind power according to claim 1, wherein: in S3, according to the basic situation of transformer structure, the corresponding modeling method and the boundary condition processing method of simulating installation and fixing type are selected to establish the transformer structure model. ​ ​ ​ 5. The method of claim 1, wherein: the pre-processing of S5 includes importing a model, generating quadrilateral or hexahedral meshes through meshing, defining material properties, defining boundary conditions and load types.

6. The method of evaluating the structural strength of a transformer for a wind power plant according to claim 1, characterized in that, After the pre-processing of S5 is completed, a calculation method is selected according to a corresponding load condition, and the calculation method specifically includes: S51: a random vibration or a transient calculation of an acceleration response spectrum is used for a transportation load; S52: a static calculation of a gravitational force and a hoisting inertia force is used for a hoisting load; S53: a random vibration, a harmonic response analysis or a response spectrum analysis is used for an operation load; S54: a sinusoidal beat frequency method is used for an extreme load; S55: a modal calculation is used for a structural dynamic characteristic; wherein the structural dynamic characteristic refers to an inherent property of a structure in response to a dynamic force, and the structural dynamic characteristic includes a natural frequency, a mode shape and damping.

7. The method of evaluating the structural strength of a transformer for a wind power plant according to claim 1, characterized in that, S7: an analysis logic flow of structural strength is established, and specifically includes: S71: material mechanical performance parameters of the structure in S2, various types of calculation loads determined in S4 and structural strength analysis diagrams obtained in S6 are taken as key decision points to establish a structural strength analysis logic flow chart; and the structural strength is evaluated according to the structural strength analysis logic flow chart; S72: select corresponding load safety factors under different load conditions according to the wind turbine design requirements in the standard , material safety factor and failure safety factor ; S73: evaluating the equivalent stress of the structure , Equivalent stress: , wherein: is the minimum yield strength specified for the EN 10025-2 European norm hot rolled structural steel; is the safety factor for failure; is the safety factor for the material; Yield safety margin coefficient: , If the yield reserve safety factor then the steering structure strength design is verified; If the yield reserve safety factor then the local stress-strain is evaluated and the Neuber rule factor is applied; Neuber's rule: , wherein: is the maximum principal stress; is the Young's modulus; If the Neuber rule factor then turn to structural strength design verification; If the Neuber rule factor then turn to redesign; S74: Assess damage to the structure under the combined load, calculate damage from the maximum principal stress , Injury: wherein: is the number of cycles applied; is the fatigue life; is the material parameter; is the fatigue life and the fatigue critical combined stress range; is the slope of the S-N curve; Fatigue reserve safety factor wherein: damage generated for the critical stress range; If fatigue reserve safety factor then turn to structural strength design verification; If the fatigue reserve safety factor then turn to redesign; S75: a first-order natural frequency of the structure is evaluated, a modal calculation is performed by using a finite element software, and the dynamic characteristic of the structure is analyzed and determined; if the first-order natural frequency in the modal calculation result is greater than or equal to 5 Hz, the structural strength design verification is performed; if the first-order natural frequency in the modal calculation result is less than 5 Hz, the structure is redesigned.

8. A computer readable storage medium, wherein: the computer readable storage medium stores program instructions, and the program instructions are used to execute the method of evaluating the structural strength of the wind power transformer according to any one of claims 1-7 when running.

9. A system for evaluating structural strength of a transformer for wind power, characterized by one or more processors are used to call and run instructions stored in a memory, so that the method of evaluating the structural strength of the wind power transformer according to any one of claims 1-7 is executed.

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