Calculation method and system for equivalent fatigue strain of floating type wind power blade

Abstract

The invention discloses a calculation method and system for equivalent fatigue strain of a floating type wind power blade. The method comprises the steps that a blade finite element model is constructed; simulating a strain value of the floating blade under the action of a wind wave flow coupling load; determining the strain control quantity of each part of the blade by combining a blade full-size type test experiment and engineering practical experience; and evaluating and calculating the safety margin of the equivalent fatigue strain of each part of the blade. The system comprises a blade modeling module, a finite element simulation module, a data processing module, an evaluation module and a judgment module. According to the method, the strain safety coefficient of the floating type blade under the equivalent fatigue load within the operation life can be simply, conveniently and efficiently evaluated, the structure is safely rechecked in the early stage of design, and the blade failure problem caused by fatigue in the operation period of the blade is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind power generation, and in particular relates to a method and system for calculating equivalent fatigue strain of floating wind turbine blades. Background Art

[0002] The technological progress of floating wind turbines is the key to the future development of wind power in deep sea areas. As an important part of the entire unit, the blades must be carefully designed in terms of cost, operation and maintenance, safety risks, etc. Since the design life of the entire unit is 25 years, and the floating blades are always subjected to alternating loads under the coupling of wind, waves and currents, it is necessary to evaluate the fatigue strain of the blades to ensure that the blades will not fail during the operation cycle.

[0003] At present, there are many methods for evaluating fatigue strain of blades in the industry. At the same time, the strain internal control values ​​of various blade components are different for each OEM, there is no unified standard, and the development and progress of the blade industry is not utilized. Therefore, combining the blade type test, engineering practice experience and high requirements for the safety of floating units, a calculation method and system for equivalent fatigue strain of floating wind turbine blades with simple calculation, efficient evaluation and conservative results is developed. Summary of the invention

[0004] The present invention provides a calculation method and system for equivalent fatigue strain of floating wind turbine blades, the purpose of which is to improve the fatigue safety of floating wind turbine blades during their service life cycle and effectively reduce damage and failure accidents of blades caused by fatigue.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: A method for calculating equivalent fatigue strain of a floating wind turbine blade comprises: According to the design data of floating wind turbine blades, a blade finite element model is constructed; According to the constructed blade finite element model, the equivalent fatigue load data under the coupling of wind load, wave load and ice load is input to obtain the blade shell strain value under the corresponding boundary conditions; According to the obtained blade shell strain value, the maximum strain of the blade leading edge, trailing edge and main beam structure is extracted; Based on the maximum strains of the leading edge, trailing edge and main beam structure of the blade, combined with blade type testing and engineering practice experience, the safety margin of blade fatigue strain is evaluated; The fatigue safety of the blade is judged based on the assessed safety margin of the blade fatigue strain.

[0006] A further improvement of the present invention is that, according to the design data of the floating wind turbine blade, a blade finite element model is constructed, including: According to the design geometric information of the floating wind turbine blade, including blade length, blade section airfoil model, airfoil geometry data, airfoil chord length, twist angle and pre-bending information, the three-dimensional geometric shape of the blade is constructed; According to the three-dimensional geometric shape of the blade, combined with the blade structure ply design drawings, the blade ply information is input, including the material design of the corresponding position, and the corresponding material thickness is given to obtain the structural three-dimensional model of the blade; According to the structural three-dimensional model of the blade and the material test report, the reasonable mechanical performance parameters of the material used are input, including transverse tensile modulus, longitudinal tensile modulus, Poisson's ratio, in-plane shear modulus and out-of-plane shear modulus, to construct a finite element model of the blade; it is required that the parameters used in the model cannot be higher than the results of the test report.

[0007] A further improvement of the present invention is that, based on the constructed blade finite element model, equivalent fatigue load data under the coupling of wind load, wave load and ice load is input to obtain the blade shell strain value under the corresponding boundary conditions, including: According to the design load data of the blade, the Markov fatigue load matrix at each cross section of the floating wind turbine blade is obtained; According to formula (1), the Markov load matrix is ​​converted into an equivalent fatigue load with a slope of SN curve m=10, where the load in the swing direction is converted to 2 million times and the load in the swing direction is converted to 1 million times;

[0008] in represents the blade element design load, represents the number of blade design runs, represents the equivalent load, represents the equivalent number, represents the slope of the stress-strain curve; Using the conversion relationship between torque and concentrated force, the equivalent fatigue torque load of each section is converted into the form of section concentrated force; According to the blade finite element model, the processed equivalent fatigue load is applied at the main beam position in the form of concentrated force data at the cross-section position along the blade length; Finite element simulation software is used to simulate the stress characteristics of the blade under equivalent fatigue load conditions and obtain the strain value of the blade shell.

[0009] A further improvement of the present invention is to evaluate the safety margin of blade fatigue strain based on the obtained maximum strain of the leading edge, trailing edge and main beam structure of the blade, combined with blade type testing and engineering practice experience, including: According to the fatigue test results in the flapping and swinging directions of the blade, combined with engineering practice experience, the maximum safe strain value of each part of the blade is determined; under 2 million equivalent fatigue loads in the swinging direction, the strain value at the leading edge does not exceed 2800, and the strain value at the trailing edge does not exceed 2500; under 1 million equivalent fatigue loads in the flapping direction, the strain value of the glass plate main beam does not exceed 2000, and the strain value of the carbon fiber main beam does not exceed 1800; According to the maximum strain of the leading edge, trailing edge and main beam structure of the blade obtained by simulation, combined with the maximum strain control value of each part, the safety margin of blade fatigue strain is evaluated, as shown in formula (2): .

[0010] A further improvement of the present invention is that the fatigue safety of the blade is judged according to the safety margin of the fatigue strain of the blade evaluated, including: When the calculated fatigue strain safety margin is greater than or equal to 1, the blade fatigue safety meets the requirements; when the fatigue strain safety margin is less than 1, the blade fatigue safety does not meet the requirements.

[0011] A floating wind turbine blade equivalent fatigue strain calculation system, comprising: The blade modeling module builds the blade finite element model based on the design data of the floating wind turbine blade; The finite element simulation module inputs the equivalent fatigue load data under the coupling of wind load, wave load and ice load according to the constructed blade finite element model, and obtains the blade shell strain value under the corresponding boundary conditions; The data processing module extracts the maximum strain of the leading edge, trailing edge and main beam structure of the blade according to the obtained blade shell strain value; The evaluation module evaluates the safety margin of blade fatigue strain based on the maximum strain of the leading edge, trailing edge and main beam structure of the blade, combined with blade type testing and engineering practice experience; The judgment module judges the fatigue safety of the blade according to the safety margin of the assessed fatigue strain of the blade.

[0012] A further improvement of the present invention is that, in the blade modeling module, a blade finite element model is constructed according to the design data of the floating wind turbine blade, including: According to the design geometric information of the floating wind turbine blade, including blade length, blade section airfoil model, airfoil geometry data, airfoil chord length, twist angle and pre-bending information, the three-dimensional geometric shape of the blade is constructed; According to the three-dimensional geometric shape of the blade, combined with the blade structure ply design drawings, the blade ply information is input, including the material design of the corresponding position, and the corresponding material thickness is given to obtain the structural three-dimensional model of the blade; According to the structural three-dimensional model of the blade and the material test report, the reasonable mechanical performance parameters of the material used are input, including transverse tensile modulus, longitudinal tensile modulus, Poisson's ratio, in-plane shear modulus and out-of-plane shear modulus, to construct a finite element model of the blade; it is required that the parameters used in the model cannot be higher than the results of the test report.

[0013] A further improvement of the present invention is that, in the finite element simulation module, according to the constructed blade finite element model, equivalent fatigue load data under the coupling of wind load, wave load and ice load is input to obtain the blade shell strain value under the corresponding boundary conditions, including: According to the design load data of the blade, the Markov fatigue load matrix at each cross section of the floating wind turbine blade is obtained; According to formula (1), the Markov load matrix is ​​converted into an equivalent fatigue load with a slope of SN curve m=10, where the load in the swing direction is converted to 2 million times and the load in the swing direction is converted to 1 million times;

[0014] in represents the blade element design load, represents the number of blade design runs, represents the equivalent load, represents the equivalent number, represents the slope of the stress-strain curve; Using the conversion relationship between torque and concentrated force, the equivalent fatigue torque load of each section is converted into the form of section concentrated force; According to the blade finite element model, the processed equivalent fatigue load is applied at the main beam position in the form of concentrated force data at the cross-section position along the blade length; Finite element simulation software is used to simulate the stress characteristics of the blade under equivalent fatigue load conditions and obtain the strain value of the blade shell.

[0015] A further improvement of the present invention is that, in the evaluation module, based on the obtained maximum strain of the leading edge, trailing edge and main beam structure of the blade, combined with blade type testing and engineering practice experience, the safety margin of blade fatigue strain is evaluated, including: According to the fatigue test results in the flapping and swinging directions of the blade, combined with engineering practice experience, the maximum safe strain value of each part of the blade is determined; under 2 million equivalent fatigue loads in the swinging direction, the strain value at the leading edge does not exceed 2800, and the strain value at the trailing edge does not exceed 2500; under 1 million equivalent fatigue loads in the flapping direction, the strain value of the glass plate main beam does not exceed 2000, and the strain value of the carbon fiber main beam does not exceed 1800; According to the maximum strain of the leading edge, trailing edge and main beam structure of the blade obtained by simulation, combined with the maximum strain control value of each part, the safety margin of blade fatigue strain is evaluated, as shown in formula (2): .

[0016] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a method for calculating equivalent fatigue strain of a floating wind turbine blade.

[0017] Compared with the prior art, the present invention has at least the following beneficial technical effects: The present invention provides a method and system for calculating equivalent fatigue strain of floating wind turbine blades. Aiming at the alternating loads borne by floating wind turbine blades under the coupling of wind, wave and current, combined with full-scale type testing of blades and engineering practice experience, a method and system for calculating equivalent fatigue strain of floating wind turbine blades has been developed. It has the advantages of simple calculation method, efficient evaluation, and relatively conservative results. At the same time, it gives the strain control value of each part of the blade under the corresponding equivalent fatigue number, provides guidance for the later blade at the fatigue strain value control level, and effectively ensures the fatigue structural safety of floating wind turbine blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 Schematic diagram of the Markov matrix for the design load of floating wind turbine blades; Figure 2 Schematic diagram of the input concentrated force load data of each cross section of the floating wind turbine blade; Figure 3 Schematic diagram of the evaluation system for equivalent fatigue strain of floating wind turbine blades. DETAILED DESCRIPTION

[0020] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0021] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0022] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0023] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0024] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0025] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0026] Example 1 The present invention provides a method for calculating equivalent fatigue strain of a floating wind turbine blade, comprising: According to the design data of floating wind turbine blades, a blade finite element model is constructed; According to the constructed blade finite element model, the equivalent fatigue load data under the coupling of wind load, wave load and ice load is input to obtain the blade shell strain value under the corresponding boundary conditions; According to the obtained blade shell strain value, the maximum strain of the blade leading edge, trailing edge and main beam structure is extracted; Based on the maximum strains of the leading edge, trailing edge and main beam structure of the blade, combined with blade type testing and engineering practice experience, the safety margin of blade fatigue strain is evaluated; The fatigue safety of the blade is judged based on the assessed safety margin of the blade fatigue strain.

[0027] In this embodiment, according to the design data of the floating wind turbine blade, a blade finite element model is constructed, including: According to the design geometric information of the floating wind turbine blade, including blade length, blade section airfoil model, airfoil geometry data, airfoil chord length, twist angle and pre-bending information, the three-dimensional geometric shape of the blade is constructed; According to the three-dimensional geometric shape of the blade, combined with the blade structure layer design drawings, the blade layer information is input, including the material design of the corresponding position, such as fiber cloth, core material, pultruded sheet and structural adhesive, and the corresponding material thickness is given to obtain the structural three-dimensional model of the blade; According to the structural three-dimensional model of the blade and the material test report, the reasonable mechanical performance parameters of the material used are input, including transverse tensile modulus, longitudinal tensile modulus, Poisson's ratio, in-plane shear modulus and out-of-plane shear modulus, to construct a finite element model of the blade; it is required that the parameters used in the model cannot be higher than the results of the test report.

[0028] In this embodiment, according to the constructed blade finite element model, the equivalent fatigue load data under the coupling of wind load, wave load and ice load is input to obtain the blade shell strain value under the corresponding boundary conditions, including: According to the design load data of the blade, the Markov fatigue load matrix at each cross section of the floating wind turbine blade is obtained; According to formula (1), the Markov load matrix is ​​converted into an equivalent fatigue load with a slope of SN curve m=10, where the load in the swing direction is converted to 2 million times and the load in the swing direction is converted to 1 million times;

[0029] in represents the blade element design load, represents the number of blade design runs, represents the equivalent load, represents the equivalent number, represents the slope of the stress-strain curve; Using the conversion relationship between torque and concentrated force, the equivalent fatigue torque load of each section is converted into the form of section concentrated force; According to the blade finite element model, the processed equivalent fatigue load is applied at the main beam position in the form of concentrated force data at the cross-section position along the blade length; Finite element simulation software is used to simulate the stress characteristics of the blade under equivalent fatigue load conditions and obtain the strain value of the blade shell.

[0030] In this embodiment, based on the maximum strains of the leading edge, trailing edge and main beam structure of the blade obtained, combined with blade type testing and engineering practice experience, the safety margin of blade fatigue strain is evaluated, including: According to the fatigue test results in the flapping and swinging directions of the blade, combined with engineering practice experience, the maximum safe strain value of each part of the blade is determined; under 2 million equivalent fatigue loads in the swinging direction, the strain value at the leading edge does not exceed 2800, and the strain value at the trailing edge does not exceed 2500; under 1 million equivalent fatigue loads in the flapping direction, the strain value of the glass plate main beam does not exceed 2000, and the strain value of the carbon fiber main beam does not exceed 1800; According to the maximum strain of the leading edge, trailing edge and main beam structure of the blade obtained by simulation, combined with the maximum strain control value of each part, the safety margin of blade fatigue strain is evaluated, as shown in formula (2): .

[0031] In this embodiment, judging the fatigue safety of the blade according to the evaluated safety margin of blade fatigue strain includes: When the calculated fatigue strain safety margin is greater than or equal to 1, the blade fatigue safety meets the requirements; when the fatigue strain safety margin is less than 1, the blade fatigue safety does not meet the requirements.

[0032] Example 2 The present invention provides a method for calculating equivalent fatigue strain of a floating wind turbine blade, comprising: Step 1: Input the geometric information of the floating wind turbine blade, including blade length, airfoil model of each section of the blade, airfoil geometry data, airfoil chord length, twist angle and pre-bend, and use 3D modeling software to construct the blade geometry diagram; Step 2: According to the structural layer design drawings of floating wind turbine blades, perform structural layering on the geometric shape drawings obtained in step 1, including glass fiber cloth (uniaxial cloth, biaxial cloth and triaxial cloth), glass fiber pultruded board, core material (Balsa, PVC) and structural adhesive. It is necessary to lay them on the corresponding positions of the blades according to the design information of the drawings to ensure the accuracy of the start and end positions, chord-wise positioning, span-wise positioning, quantity and material thickness data of each material, and strive to be basically consistent with the manufactured blades; Step 3: According to the material parameters of floating wind turbine blades, combined with the mechanical properties test reports of each material, determine the reasonable performance parameters and input them into the model obtained in step 2, including the transverse tensile modulus. , longitudinal tensile modulus , in-plane shear modulus , out-of-plane shear modulus and , and the Poisson coupling coefficient , construct the blade finite element model, where Table 1 shows the name of the material used for the blade and the corresponding mechanical performance parameters; Table 1 Mechanical properties of blade materials

[0033] Step 4: According to the design load data of the floating wind turbine blade, extract the Markov load matrix at the first section in the swing direction, i.e. the blade position 0m. Some data are as follows: Figure 1 As shown, the first row represents the load amplitude, the first column represents the load mean, and the data in the table represent the number of occurrences; Step 5: Use formula (1) to convert the data of the Markov load matrix at the first section into the equivalent fatigue load value when the SN curve (stress-life) slope is m=10 and the number of times is 2 million;

[0034] in Indicates the first row The magnitude of the column, represents the total number of amplitudes, represents the slope of the stress-life curve, Indicates the life of floating wind turbine blades, 100 million times. represents the equivalent load value, Indicates the equivalent number of cycles, which is 2 million times; Step 6: Repeat steps 4 and 5 to obtain the equivalent fatigue load data at each cross section of the floating wind turbine blade, and convert the bending moment load into the form of concentrated force load. Considering the impact of the real environment on the test, multiply the concentrated force load data of each cross section by the test reduction factor 1.3285. The final concentrated force data of each cross section is as follows: Figure 2 As shown; Step 7: Input the blade cross-section concentrated force load data obtained in step 6 into the main beam position of the blade finite element model in step 3, and use finite element simulation software to simulate the force characteristics of the blade under the equivalent fatigue load condition in the swing direction; Step 8: According to step 7, the force characteristics of the blade under the equivalent fatigue load condition in the swing direction are simulated to obtain the strain values ​​of all positions of the blade shell; Step 9: Extract the maximum absolute values ​​of strain at the leading edge and trailing edge of the floating wind turbine blade, which are 2388 and 2148 respectively; Step 10: Based on the blade type test and engineering practice experience, the maximum strain control value of each part of the blade is determined, with the leading edge at 2500 and the trailing edge at 2200. The safety margin of blade fatigue strain is evaluated using the above formula (2). The result is:

[0035]

[0036] Step 11: The fatigue strain safety margin values ​​of the leading edge and trailing edge of the blade obtained in step 10 are both greater than 1, indicating that the fatigue strain of the blade meets the requirements; Example 3 like Figure 2 As shown, the present invention provides a floating wind turbine blade equivalent fatigue strain calculation system, comprising: The blade modeling module builds the blade finite element model based on the design data of the floating wind turbine blade; The finite element simulation module inputs the equivalent fatigue load data under the coupling of wind load, wave load and ice load according to the constructed blade finite element model, and obtains the blade shell strain value under the corresponding boundary conditions; The data processing module extracts the maximum strain of the leading edge, trailing edge and main beam structure of the blade according to the obtained blade shell strain value; The evaluation module evaluates the safety margin of blade fatigue strain based on the maximum strain of the leading edge, trailing edge and main beam structure of the blade, combined with blade type testing and engineering practice experience; The judgment module judges the fatigue safety of the blade according to the safety margin of the assessed fatigue strain of the blade.

[0037] Example 4 The present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for calculating the equivalent fatigue strain of a floating wind turbine blade are implemented.

[0038] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0039] The present application is described with reference to the flowcharts and / or block diagrams of the methods, systems and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of the processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A system that specifies the functions of a box or multiple boxes.

[0040] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0041] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0042] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0043] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for calculating equivalent fatigue strain of floating wind turbine blades, characterized in that: include: According to the design data of floating wind turbine blades, a blade finite element model is constructed; According to the constructed blade finite element model, the equivalent fatigue load data under the coupling of wind load, wave load and ice load is input to obtain the blade shell strain value under the corresponding boundary conditions; According to the obtained blade shell strain value, the maximum strain of the blade leading edge, trailing edge and main beam structure is extracted; Based on the maximum strains of the leading edge, trailing edge and main beam structure of the blade, combined with blade type testing and engineering practice experience, the safety margin of blade fatigue strain is evaluated; The fatigue safety of the blade is judged based on the assessed safety margin of the blade fatigue strain.

2. The method for calculating equivalent fatigue strain of a floating wind turbine blade according to claim 1, characterized in that: According to the design data of floating wind turbine blades, a blade finite element model is constructed, including: According to the design geometric information of the floating wind turbine blade, including blade length, blade section airfoil model, airfoil geometry data, airfoil chord length, twist angle and pre-bending information, the three-dimensional geometric shape of the blade is constructed; According to the three-dimensional geometric shape of the blade, combined with the blade structure ply design drawings, the blade ply information is input, including the material design of the corresponding position, and the corresponding material thickness is given to obtain the structural three-dimensional model of the blade; According to the structural three-dimensional model of the blade and the material test report, the reasonable mechanical performance parameters of the material used are input, including transverse tensile modulus, longitudinal tensile modulus, Poisson's ratio, in-plane shear modulus and out-of-plane shear modulus, to construct a finite element model of the blade; it is required that the parameters used in the model cannot be higher than the results of the test report.

3. The method for calculating equivalent fatigue strain of a floating wind turbine blade according to claim 1, characterized in that: According to the constructed blade finite element model, the equivalent fatigue load data under the coupling of wind load, wave load and ice load is input to obtain the blade shell strain value under the corresponding boundary conditions, including: According to the design load data of the blade, the Markov fatigue load matrix at each cross section of the floating wind turbine blade is obtained; According to formula (1), the Markov load matrix is ​​converted into an equivalent fatigue load with a slope of SN curve m=10, where the load in the swing direction is converted to 2 million times and the load in the swing direction is converted to 1 million times; in represents the blade element design load, represents the number of blade design runs, represents the equivalent load, represents the equivalent number, represents the slope of the stress-strain curve; Using the conversion relationship between torque and concentrated force, the equivalent fatigue torque load of each section is converted into the form of section concentrated force; According to the blade finite element model, the processed equivalent fatigue load is applied at the main beam position in the form of concentrated force data at the cross-section position along the blade length; Finite element simulation software is used to simulate the stress characteristics of the blade under equivalent fatigue load conditions and obtain the strain value of the blade shell.

4. The method for calculating equivalent fatigue strain of a floating wind turbine blade according to claim 1, characterized in that: Based on the maximum strain of the leading edge, trailing edge and main beam structure of the blade, combined with blade type testing and engineering practice experience, the safety margin of blade fatigue strain is evaluated, including: According to the fatigue test results in the flapping and swinging directions of the blade, combined with engineering practice experience, the maximum safe strain value of each part of the blade is determined; under 2 million equivalent fatigue loads in the swinging direction, the strain value at the leading edge does not exceed 2800, and the strain value at the trailing edge does not exceed 2500; under 1 million equivalent fatigue loads in the flapping direction, the strain value of the glass plate main beam does not exceed 2000, and the strain value of the carbon fiber main beam does not exceed 1800; According to the maximum strain of the leading edge, trailing edge and main beam structure of the blade obtained by simulation, combined with the maximum strain control value of each part, the safety margin of blade fatigue strain is evaluated, as shown in formula (2): 。 5. A method for calculating equivalent fatigue strain of floating wind turbine blades according to claim 1, characterized in that: The fatigue safety of the blade is judged based on the safety margin of the assessed blade fatigue strain, including: When the calculated fatigue strain safety margin is greater than or equal to 1, the blade fatigue safety meets the requirements; when the fatigue strain safety margin is less than 1, the blade fatigue safety does not meet the requirements.

6. A floating wind turbine blade equivalent fatigue strain calculation system, characterized in that: include: The blade modeling module builds the blade finite element model based on the design data of the floating wind turbine blade; The finite element simulation module inputs the equivalent fatigue load data under the coupling of wind load, wave load and ice load according to the constructed blade finite element model, and obtains the blade shell strain value under the corresponding boundary conditions; The data processing module extracts the maximum strain of the leading edge, trailing edge and main beam structure of the blade according to the obtained blade shell strain value; The evaluation module evaluates the safety margin of blade fatigue strain based on the maximum strain of the leading edge, trailing edge and main beam structure of the blade, combined with blade type testing and engineering practice experience; The judgment module judges the fatigue safety of the blade according to the safety margin of the assessed fatigue strain of the blade.

7. A floating wind turbine blade equivalent fatigue strain calculation system according to claim 6, characterized in that: In the blade modeling module, a blade finite element model is constructed based on the design data of the floating wind turbine blade, including: According to the design geometric information of the floating wind turbine blade, including blade length, blade section airfoil model, airfoil geometry data, airfoil chord length, twist angle and pre-bending information, the three-dimensional geometric shape of the blade is constructed; According to the three-dimensional geometric shape of the blade, combined with the blade structure ply design drawings, the blade ply information is input, including the material design of the corresponding position, and the corresponding material thickness is given to obtain the structural three-dimensional model of the blade; According to the structural three-dimensional model of the blade and the material test report, the reasonable mechanical performance parameters of the material used are input, including transverse tensile modulus, longitudinal tensile modulus, Poisson's ratio, in-plane shear modulus and out-of-plane shear modulus, to construct a finite element model of the blade; it is required that the parameters used in the model cannot be higher than the results of the test report.

8. The floating wind turbine blade equivalent fatigue strain calculation system according to claim 6, characterized in that: In the finite element simulation module, according to the constructed blade finite element model, the equivalent fatigue load data under the coupling of wind load, wave load and ice load is input to obtain the blade shell strain value under the corresponding boundary conditions, including: According to the design load data of the blade, the Markov fatigue load matrix at each cross section of the floating wind turbine blade is obtained; According to formula (1), the Markov load matrix is ​​converted into an equivalent fatigue load with a slope of SN curve m=10, where the load in the swing direction is converted to 2 million times and the load in the swing direction is converted to 1 million times; in represents the blade element design load, represents the number of blade design runs, represents the equivalent load, represents the equivalent number, represents the slope of the stress-strain curve; Using the conversion relationship between torque and concentrated force, the equivalent fatigue torque load of each section is converted into the form of section concentrated force; According to the blade finite element model, the processed equivalent fatigue load is applied at the main beam position in the form of concentrated force data at the cross-section position along the blade length; Finite element simulation software is used to simulate the stress characteristics of the blade under equivalent fatigue load conditions and obtain the strain value of the blade shell.

9. A floating wind turbine blade equivalent fatigue strain calculation system according to claim 6, characterized in that: In the evaluation module, the safety margin of blade fatigue strain is evaluated based on the maximum strain of the leading edge, trailing edge and main beam structure of the blade, combined with blade type testing and engineering practice experience, including: According to the fatigue test results in the flapping and swinging directions of the blade, combined with engineering practice experience, the maximum safe strain value of each part of the blade is determined; under 2 million equivalent fatigue loads in the swinging direction, the strain value at the leading edge does not exceed 2800, and the strain value at the trailing edge does not exceed 2500; under 1 million equivalent fatigue loads in the flapping direction, the strain value of the glass plate main beam does not exceed 2000, and the strain value of the carbon fiber main beam does not exceed 1800; According to the maximum strain of the leading edge, trailing edge and main beam structure of the blade obtained by simulation, combined with the maximum strain control value of each part, the safety margin of blade fatigue strain is evaluated, as shown in formula (2): 。 10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the computer program implements the steps of a method for calculating equivalent fatigue strain of a floating wind turbine blade according to any one of claims 1 to 5.

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