Fatigue analysis method for offshore floating type fan foundation, electronic equipment and medium

Abstract

The invention provides an offshore floating type fan foundation fatigue analysis method, electronic equipment and a medium, a stress superposition-based multi-load fatigue analysis method is established, and linear superposition is performed on a time sequence tower bottom load response, a time sequence mooring response and a time sequence wave response under the same working condition to obtain a stress time calendar curve under the corresponding working condition; carrying out rain flow counting on the stress time calendar curve, and combining an S-N curve to obtain the total fatigue damage of the working condition; and performing weighted calculation on the total fatigue damage of all working conditions in the target service time of the fan foundation to obtain full-working-condition fatigue damage. According to the method, the influence of each load is fully considered on the overall scale, different loads of the same working condition are matched, the method is suitable for various complex wind and wave coupling conditions, stress time sequences of different loads are superposed and subjected to fatigue treatment, the full-working-condition fatigue damage of the fan foundation under multiple load components is obtained, and the precision of fatigue damage analysis is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of offshore wind power, and in particular relates to a fatigue analysis method, electronic equipment and medium for an offshore floating wind turbine foundation. Background Art

[0002] As an innovative technology in the field of offshore wind power, floating wind power is showing a very broad development prospect. With the growing demand for clean energy and the urgent need to develop deep-sea wind energy resources, floating wind turbine foundations have become a key bridge connecting the rich wind energy in deep sea areas with the demand for land electricity with their unique advantages.

[0003] There are many complex coupling effects in the foundation structure of floating wind turbines, such as the interaction between blades, towers, buoys, anchor cables, etc., the coupling between rigid body motion and elastic deformation, and the coupling between aerodynamics, structure, and hydrodynamics. The fatigue strength check of floating wind turbine foundations needs to comprehensively consider these complex coupling effects to ensure safe and reliable operation within the design life.

[0004] Patent application CN11458015A discloses a method for analyzing local stress in the foundation of a floating wind turbine structure in the time domain. The method obtains the coupled motion state of the floating wind turbine structure by establishing a multi-body analysis model, and then realizes the calculation of the wave distribution load of the floating foundation by replaying the wave surface time history and motion state, combined with the solution of the time domain potential flow, and obtains the local time domain stress of the floating foundation by load mapping and solving the control equation; by performing probability statistical analysis and Fourier analysis on the time domain stress, combined with random signal reconstruction and derivation methods, the local stress batch random multiplication is realized, and then the local ultimate strength verification and local fatigue strength verification of the structure are completed by extreme value analysis method and fatigue damage analysis theory. It solves the local stress for motion response and fatigue strength analysis, but does not take into account the full working condition and multi-load fatigue analysis, and the accuracy of its local stress analysis is low. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies in the prior art and provide a method, electronic equipment and medium for fatigue analysis of an offshore floating wind turbine foundation, which considers the influence of various loads on an overall scale and improves the accuracy of fatigue analysis of the wind turbine foundation.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A fatigue analysis method for an offshore floating wind turbine foundation comprises the following steps:

[0008] According to the structure of the offshore floating wind turbine foundation, a finite element model of the offshore floating wind turbine foundation is constructed, wherein the structure of the offshore floating wind turbine foundation includes a diagonal brace, an upper connecting beam, a column, a lower connecting beam, a nacelle, a tower, and a mooring chain;

[0009] A unit force is applied to the rigid connection between the tower bottom and the column to obtain the unit force response of the tower bottom load. The tower bottom loads of different working conditions are multiplied by the unit force response of the tower bottom load to obtain the time series tower bottom load responses of different working conditions.

[0010] Apply unit force at the mooring chain connection to obtain the mooring unit force response, and multiply the mooring force under different working conditions by the mooring unit force response to obtain the time-series mooring response under different working conditions;

[0011] Based on the random wave spectrum, the Morrison equation is used to calculate the wave load on the wind turbine foundation, and the foundation motion response and hydrodynamic pressure distribution in each regular wave are obtained. Finite element analysis is performed on the wind turbine foundation under each hydrodynamic pressure condition to obtain the wave response under different conditions.

[0012] The wave response is reconstructed into a time series wave response. The expression of the time series wave response is as follows:

[0013]

[0014] The time-series tower bottom load response, time-series mooring response, and time-series wave response of the same working condition are linearly superimposed to obtain the stress time history curve of the corresponding working condition; the rain flow count is performed on the stress time history curve, and the total fatigue damage of the working condition is obtained by combining it with the SN curve;

[0015] The total fatigue damage of all working conditions within the target service time of the wind turbine foundation is weighted and calculated to obtain the fatigue damage of all working conditions. The expression of fatigue damage of all working conditions is as follows:

[0016]

[0017] Among them, σ(t) is the time series wave response, k n is the wave number, ε n is the phase angle, H(ω n ) is the amplitude-response transfer function, ω n is the wave frequency, Δω is the frequency interval, S ζ (ω n ) is the wave response spectrum, is the standard cosine wave amplitude; D is the fatigue damage under all working conditions, D i is the total fatigue damage of the i-th working condition, m is the number of working conditions, T is the target service time of the wind turbine foundation, T i is the time of the i-th working condition.

[0018] The present invention establishes a multi-load fatigue analysis method based on stress superposition, which fully considers the influence of each load on the overall scale, matches different loads under the same working condition, is applicable to a variety of complex wind and wave coupling conditions, superimposes the stress time series of different loads and performs fatigue treatment, and obtains the full-condition fatigue damage of the wind turbine foundation under multiple load components, thereby improving the accuracy of fatigue damage analysis of the wind turbine foundation.

[0019] Furthermore, the tower bottom load unit force response includes F x 、F y 、F z 、M x 、M y 、M z Six-DOF unit force response, where F x 、F y 、F z are the unit forces in the X, Y, and XY directions applied to the rigid connection between the tower bottom and the column, respectively. x 、M y 、M z It is the unit moment in the X, Y and XY directions applied to the rigid connection between the tower base and the column.

[0020] Furthermore, the mooring unit force response includes different mooring chains F x _j, F y _j, F z _j three-degree-of-freedom unit force response, where F x _j, F y _j, F z _j are the unit forces in the X, Y, and XY directions applied at the j-th mooring chain connection.

[0021] Furthermore, the wave response includes wave responses in X, Y, and XY directions.

[0022] Based on the same inventive concept, the present invention also provides an electronic device, including:

[0023] one or more processors;

[0024] A memory having one or more programs stored thereon, which, when executed by the one or more processors, enables the one or more processors to implement the steps of the offshore floating wind turbine foundation fatigue analysis method.

[0025] Based on the same inventive concept, the present invention also provides a computer-readable storage medium storing a computer program, which implements the steps of a fatigue analysis method for an offshore floating wind turbine foundation when executed by a processor.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention establishes a multi-load fatigue analysis method based on stress superposition, which fully considers the influence of each load on the overall scale, matches different loads under the same working condition, is applicable to a variety of complex wind and wave coupling conditions, superimposes the stress time series of different loads and performs fatigue treatment, and outputs the total fatigue damage of the wind turbine foundation under multiple load components under all working conditions, thereby improving the accuracy of fatigue damage analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of a fatigue analysis method for an offshore floating wind turbine foundation according to the present invention;

[0029] Figure 2 It is a structural schematic diagram of the offshore floating wind turbine foundation of the present invention;

[0030] Figure 3 A schematic diagram of the generation of a finite element model of an offshore floating wind turbine foundation according to the present invention;

[0031] Figure 4 A finite element model of the offshore floating wind turbine foundation of the present invention;

[0032] Figure 5 A wet surface model of the offshore floating wind turbine foundation of the present invention;

[0033] Figure 6 Morrison model of the offshore floating wind turbine foundation of the present invention;

[0034] Figure 7 This is the fatigue condition of the bottom node of the floating wind turbine of the present invention.

[0035] In the figure: 1- wind turbine tower bottom load, 2- mooring force, 3- water pressure and inertia force, 4- cabin, 5- tower, 6- diagonal brace, 7- upper connecting beam, 8- column, 9- lower connecting beam. DETAILED DESCRIPTION

[0036] The present invention will be described in detail below in conjunction with the embodiments. It should be noted that the embodiments and features of the embodiments of the present invention can be combined with each other without conflict. For the convenience of description, if the words "upper", "lower", "left" and "right" appear in the following, they only indicate that the upper, lower, left and right directions are consistent with the drawings themselves, and do not limit the structure.

[0037] Example

[0038] like Figure 1The present embodiment provides a fatigue analysis method for an offshore floating wind turbine foundation, including a finite element model, a structural calculation combination module and a calculation execution module. The finite element model is quickly generated by reading the standard design value, and can be used for finite element calculation after further refining the structure. The structural calculation combination module calls the finite element program to calculate the unit force response of the wind turbine tower bottom load and the mooring force load, and calculates the wave response spectrum under short-term sea conditions. The calculation execution module serves as a control program to perform working condition management and uniformly call the structural calculation combination module to output sub-item fatigue damage, and perform damage superposition.

[0039] The finite element model establishes a mapping relationship between the main scale parameters and the structural layout. The structural calculation module assumes that the entire structure is a linear system, and the responses under the action of each fatigue load component acting on the wind turbine foundation can be linearly superimposed. The fatigue loads acting on the wind turbine foundation at a certain moment include dynamic water pressure caused by waves, radiation water pressure caused by movement, acceleration, static water pressure, loads transmitted by the wind turbine, mooring force and water pressure in the cabin. The responses of these loads are numerically simulated through a series of standard load conditions. The calculation execution module reconstructs the response time series of each condition based on the standard response, and finally superimposes the stress time series and performs fatigue post-processing to obtain the total fatigue damage of the wind turbine foundation under multiple load components.

[0040] According to Figure 2 The floating foundation and mooring system of the floating offshore wind turbine shown in the figure are used to establish a finite element model (such as Figure 4 ), including a nacelle 4, a tower 5, a diagonal brace 6, an upper connecting beam 7, a column 8, a lower connecting beam 9, and a mooring chain, whose shape parameters and internal plate, rib, beam type values ​​and span are explicit parameters. The fatigue analysis method involved in this embodiment considers the influence of tower bottom load 1, mooring force 2, water pressure and inertia force 3.

[0041] like Figure 3 This is a flow chart of finite element model generation. The design parameter table is designed based on the specification to obtain the size information of the plate, reinforcement and beam. The Python interface program reads the design values ​​of the design parameter table and covers them in the JavaScript program. The program is divided into two parts: geometry and structure, which are roughly classified into columns, lower connecting beams, diagonal braces, upper connecting beams and cabins. It takes about 20 seconds to generate the target structural model, and it takes 2 to 3 days to manually model to this depth. About 800 batch processing command lines are covered, which stipulate about 10,000 beam units and about 100 plate and shell units.

[0042] The finite element model provides a unified structural model for subsequent finite element calculations, which includes the main structure of the three-column floating wind turbine foundation, including the columns, nacelle, diagonal braces, lower connecting beams, and upper connecting beams, but does not include structural reinforcement structures and connection structures.

[0043] The finite element model is written in JavaScript, and the input design parameters are uniformly read from the standard design table through the Python control program. The control program searches for the corresponding plate, beam, and reinforcement positions and cross-section models, and makes unified modifications.

[0044] The model explicit parameters include the main scale parameters (including the position, size, angle and other information of the diagonal brace, upper connecting beam, lower connecting beam and column, which can describe the Figure 2 The model constraint relationship is reflected in the finite element model program. The main ribs and beams are calculated and arranged through the input explicit parameters and automatically generated. The output finite element model can be directly used for finite element calculation after supplementing the connection and strengthening structure, and provide input for the fatigue calculation execution module.

[0045] The structural calculation combined module includes three parts: wind turbine tower bottom load, water pressure and inertia force, and mooring force, which are converted by the following formula:

[0046]

[0047] in, is the structural inertia force, is the structural damping, C struc Δq is the structural restoring force, ΔF aero is the fan aerodynamic force, ΔF hydro is the hydrodynamic force, ΔF moor is the mooring force. The wind turbine tower bottom load part takes into account ΔF aero With ΔF hydro Impact on the fan, water pressure and inertia force are considered With ΔF hydro The effect on the wind turbine foundation, the mooring force part considers ΔF moor impact.

[0048] The wind turbine tower bottom load part is based on the finite element model. The unit force is applied to the rigid connection between the tower bottom and the column and mapped to the top of the column through the rigid connection at the tower bottom to obtain the unit force response of the tower bottom load. It can be realized through GeniE and Sestra. The unit force response of the tower bottom load includes F x 、F y 、F z 、M x 、M y 、M z Six degrees of freedom unit response, where F x 、F y 、F z is the unit force in three directions (X, Y, XY directions) applied at the bottom of the tower, M x 、M y 、M zis the unit moment in three directions applied at the bottom of the tower. The post-processing program linearly superimposes and calculates the time series tower bottom load response of different working conditions. After superimposing it on the total stress time series, the standard fatigue processing program combines the rain flow counting method and the SN curve to obtain fatigue damage based on this response.

[0049] The mooring force part is based on the finite element model. The unit force is applied at the mooring chain connection and mapped to the outer surface of the wind turbine foundation through the beam unit. The unit force response at the mooring chain connection is calculated. The unit forces of different mooring chains are numbered separately, such as (F x _1, F y _1, F z _1, F x _2. F y _2. F z _2......), where 1 and 2 represent different mooring chains. Based on the above response results, the post-processing program linearly superimposes and combines to obtain the time series mooring response of different working conditions. After superimposing it to the total stress time series, the standard fatigue processing program combines the rain flow counting method and the SN curve to obtain fatigue damage based on the response.

[0050] The water pressure and inertial force are calculated by applying wave spectrum loads. To avoid repeated consideration of the influence of the wind turbine, the mass of the tower and the nacelle are removed on the basis of the above finite element model. The inertial force of the wind turbine foundation is represented by the mass stiffness matrix obtained by integrated calculation (multi-body coupled motion analysis). The transfer function and wave response of the wind turbine foundation are obtained by random wave spectrum calculation: given that the wind turbine foundation is acted upon by a regular wave of a given amplitude and frequency, the wave load acting on the wind turbine foundation is calculated by linear approximation according to the hydrodynamic theory. Then, the finite element method is used to perform quasi-static analysis on the wind turbine foundation structure to obtain the stress and displacement responses (wave response) of the wind turbine foundation structure. The wave response amplitude and the wave amplitude ratio of the obtained hot spot are taken to obtain the value of the transfer function at that frequency. By taking a series of different frequencies and calculating according to the above method, the distribution law of the transfer function with respect to frequency can be obtained. This process can be achieved by Wadam, Sestra, etc.

[0051] Based on the wave response (σ in different directions) according to formula (1) and formula (2), x _R,σ y _R,σ xy _R,σ x _I,σ y _I,σ xy _I) Reconstruct the time series wave response, where σ x _R,σ y _R,σ xy _R is the real part of the principal stress component of the wave response in three directions, σ x _I,σ y _I,σxy _I is its imaginary part. After superimposing it to the total stress time series, the standard fatigue processing procedure obtains fatigue damage based on this response combined with the rain flow counting method and the SN curve.

[0052]

[0053]

[0054] Among them, σ(t) is the time series wave response, k n is the wave number, ε n is the phase angle, H(ω n ) is the amplitude-response transfer function, ω n is the wave frequency, Δω is the frequency interval, S ζ (ω n ) is the wave response spectrum, is the standard cosine wave amplitude.

[0055] The calculation execution module includes the working condition management file, stress combination program and standard fatigue processing program. The working condition management file includes the wind turbine tower bottom load Tower Force file, mooring force file, short-term sea state Sea State file and duration. The stress combination program manages the above working conditions in a unified manner, and can specify the SCF value and SN curve preset by the program, and then perform stress time series combination. The standard fatigue processing program reads the superimposed stress time series and performs rain flow counting, and then performs fatigue damage calculation based on the SN curve given by the above program.

[0056] The SN curve is a curve that uses the fatigue strength of a standard material specimen as the ordinate and the logarithm of the fatigue life lg N as the abscissa. It represents the relationship between the fatigue strength and fatigue life of a standard specimen under certain cycle characteristics. It is also called a stress-life curve.

[0057] The selection of SCF value (stress concentration factor) and SN curve can refer to the relevant provisions of the "Technical Guidelines for Fatigue Strength Assessment of Marine Engineering Structures". The reference curves for different floating body positions are different, so the reference values ​​are preset in the program and can be selected according to the actual situation (mainly whether there is seawater immersion).

[0058] Table 1 is the partial mooring force file at time 0s under a certain working condition, which contains the partial forces of a total of 7 mooring chains in three directions, with a calculation time of 600s and a time interval of 0.05s.

[0059] Table 2 is a Sea State file of some short-term sea conditions under the same working conditions. The 8 components with the lowest frequency under this sea condition record the information of frequency, direction, wave height (amplitude), and phase of different components. This embodiment uses JONSWAP spectrum (random wave spectrum) for description.

[0060] Table 3 is the Tower Force file of some tower bottom loads under the same working condition. The tower bottom loads from 0s to 0.15s under this working condition record its components in six degrees of freedom, with a calculation time of 600s and a calculation interval of 0.05s, which is consistent with the mooring force input file.

[0061] Table 1 Mooring force input file

[0062]

[0063]

[0064] Table 2 Short-term sea state input file

[0065] Frequency(HZ) Amplitude(m) Direction(rad) Phase(rad) 0.033333 2.89E-69 6.42281 0.344218 0.034667 2.84E-59 6.42281 -0.66384 0.036 4.91E-51 6.42281 -3.10189 0.037333 3.38E-44 6.42281 -3.02155 0.038667 1.75E-38 6.42281 -0.05345 0.04 1.12E-33 6.42281 -2.43666 0.041333 1.29E-29 6.42281 0.83085 0.042667 3.64E-26 6.42281 -2.17618

[0066] Table 3 Tower bottom load input file

[0067] Time Tower Fx Tower Fy Tower Fz Tower Mx Tower My Tower Mz (s) (kN) (kN) (kN) (kNm) (kNm) (kNm) 0.000 344.201 -18.888 -18970.950 3079.432 25300.270 -297.197 0.050 336.644 -14.454 -18971.400 2783.557 25157.470 -275.658 0.100 333.689 -10.655 -18972.270 2527.563 25238.780 -264.861 0.150 336.879 -11.292 -18973.050 2417.673 25625.550 -253.463

[0068] Based on the calculation combination module, the calculation combination of the tower bottom load unit force response, mooring unit force response and wave response is completed, and the response reconstruction of the input file is completed. The main work of this process is to construct the transfer function between the external load of the wind turbine foundation and the unit force response and wave response. The following takes a certain grid as an example to illustrate the calculation combination process of this method.

[0069] Since the tower bottom load is a direct result of the integrated calculation, the mass of the tower and the nacelle does not need to be considered when calculating its unit standard response, thus ensuring that the inertia of the wind turbine is not calculated repeatedly. Figure 4 For the structural finite element model used for tower bottom load calculation, its boundary conditions must be consistent with the overall model, and a unit force is applied to the rigid link at the bottom of the tower to calculate the response. The direct result of the calculation is the tower bottom load response (Towerstress file). Table 4 below takes a certain grid as an example and lists the tower bottom load response at the grid.

[0070] Table 4 Partial tower bottom load response (Pa)

[0071] <![CDATA[Tower bottom load response σ x > <![CDATA[Bottom tower load response σ y > <![CDATA[Tower bottom load response σ xy > Tower Fx 1132400 -18245.9 25024.1 Tower Fy -2145620 35993.2 6521.95 Tower Fz 51486.4 344.875 -782.817 Tower Mx 49332.8 -561.242 -2427.34 Tower My 28312.8 -456.795 517.306 Tower Mz -6353.02 600.254 -20804.6

[0072] The mooring force and wave spectrum response are calculated by load mapping. Figure 4 The wet surface model is Figure 5Morrison model is used to calculate the wave loads acting on the wet surface unit and Morrison unit according to the three-dimensional potential flow theory and Morrison equation, and the basic motion response and hydrodynamic pressure distribution in each regular wave are obtained. Then, the calculated wave loads are transferred to the finite element model of the wind turbine foundation structure, and the structural finite element analysis is performed on each hydrodynamic load condition to obtain the calculated stress of the node structure. The finite element model adopts Figure 4 In the calculation, the mass matrix of the wind turbine foundation needs to be replaced by the result of integrated calculation to reflect the influence of inertial force in the motion of the floating body. The direct results of the calculation are mooring response (Mooringstress file), static response (staticstress file) and wave response (wavestress_dir file).

[0073] The wet surface model only expresses the outer surface of the underwater part of the wind turbine foundation, and the Morrison model simplifies the wind turbine foundation structure into a beam. The wet surface model and the Morrison model include part of the structure of the finite element model.

[0074] Morrison equation: The wave force at each water depth is calculated using the wave particle velocity, acceleration and column diameter as parameters, and then the pile column wave force is obtained by integrating along the column length.

[0075] Some examples of mooring response (Mooringstress file) are shown in Table 5. This file records the mooring response of a grid under unit force, including the results of a total of 7 mooring chains in three degrees of freedom.

[0076] Table 5 Partial mooring response (Pa)

[0077]

[0078]

[0079] Some examples of staticstress files are shown in Table 6. This file records Figure 4 The finite element model shown shows the stress conditions when it is in equilibrium in still water. Under this condition, only the effects of gravity and water pressure are considered.

[0080] Table 6 Static partial response (Pa)

[0081] <![CDATA[Static response σ x > <![CDATA[Static response σ y > <![CDATA[Static response σ xy > Stress -4119110 -6591580 -1380860

[0082] Some examples of wave responses (wavestress_dir files) are shown in Table 7, which records Figure 4The partial wave response of the finite element model shown in the figure at certain specific frequencies, unit wave heights, and specific directions is different from the concentrated load. The wave response and the load have different phase differences, so the wave response file needs to record this information. The real and imaginary parts of the stress components in the three directions are given in Table 7. The specific frequencies are determined by measured values. In this example, wave components with a total probability of occurrence greater than 90% are selected to cover the calculation of fatigue conditions.

[0083] Table 7 Wave response (Pa)

[0084]

[0085] Based on the above wave response data, the above formulas (1) and (2) can be used to construct σ in different directions: x , σ y , σ xy The wave response stress time series is divided into two steps. The first step is to obtain the amplitude of the wave with a specific frequency through the sea state spectrum. In this example, the initial frequency is set to 0.0333333HZ and the frequency interval is 1 / 750HZ.

[0086] In the second step, the stresses in each direction in Table 7 need to be combined and reconstructed into time series signals, and the stress response adopts the standard cosine wave form.

[0087] For the data types in Table 7, the wave response σ x , σ y , σ xy The timing is combined separately. When combining, first for each frequency in Table 2, interpolate the data in Table 7. In this example, Lagrange interpolation, Newton interpolation or Hermite interpolation is used. The response data in Table 7 is actually the transfer function of amplitude-response, thereby obtaining the amplitude-response transfer function H(ω) corresponding to the unit wave height of the frequency in Table 2 n ), an Solving formula (1), we can get n The phase angle can be obtained from the data in Table 7, thereby obtaining the time series wave response σ(t).

[0088] Solve the wave response σ at the initial frequency x The corresponding phase angle ε n Take as an example, the transfer function obtained after interpolation is processed as follows:

[0089]

[0090] In the formula, re_H(ω n ) is the wave response σ x The real part of the transfer function, im_H(ω n ) is the wave response σx The imaginary part of the transfer function.

[0091] The operating condition calculation is performed based on the reconstructed time-series tower bottom load response, time-series mooring response, and time-series wave response.

[0092] The calculation program performs calculation combinations for different working conditions at each time step to obtain a complete stress-time history curve for the corresponding working condition. Then, the total fatigue damage under the working condition is obtained based on the rain flow count and SN curve statistics. The fatigue damage under all working conditions is calculated by weighted calculation based on the proportion of the target service life of the wind turbine foundation. The fatigue damage under all working conditions is calculated as shown in formula (4):

[0093]

[0094] In the formula, D and D i are the fatigue damage of all working conditions and the total fatigue damage of a certain working condition, m is the total number of working conditions, T and T i They are the basic target service time of the wind turbine and the service time under certain working conditions respectively.

[0095] Take a certain grid as an example. The SN curve of this grid adopts the E curve in air, the stress concentration factor SCF is 1.6, and the plate thickness is 30mm. For each grid that needs to be counted, this setting needs to be automatically generated by the post-processing program. Figure 6 The fatigue condition of the bottom node of the floating wind turbine. This method uses the frequency domain transfer function to reconstruct the time domain signal, which greatly reduces the calculation time.

[0096] Another embodiment of the present invention provides an electronic device, including:

[0097] one or more processors;

[0098] A memory stores one or more programs, and when the one or more programs are executed by one or more processors, the one or more processors implement the steps of the offshore floating wind turbine foundation fatigue analysis method.

[0099] In some implementations, the memory may be a high-speed random access memory (RAM), and may also include a non-volatile memory, such as at least one disk memory.

[0100] In some other implementations, the processor may be a central processing unit (CPU), a digital signal processor (DSP), or other general-purpose processors of various types, which are not limited herein.

[0101] Another embodiment of the present invention provides a computer-readable storage medium storing a computer program, which implements the steps of a method for fatigue analysis of an offshore floating wind turbine foundation when the computer program is executed by a processor.

[0102] The contents explained in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

Claims

1. A fatigue analysis method for an offshore floating wind turbine foundation, characterized in that: The process includes: According to the structure of the offshore floating wind turbine foundation, a finite element model of the offshore floating wind turbine foundation is constructed, wherein the structure of the offshore floating wind turbine foundation includes a diagonal brace, an upper connecting beam, a column, a lower connecting beam, a nacelle, a tower, and a mooring chain; A unit force is applied to the rigid connection between the tower bottom and the column to obtain the unit force response of the tower bottom load. The tower bottom loads of different working conditions are multiplied by the unit force response of the tower bottom load to obtain the time series tower bottom load responses of different working conditions. Apply unit force at the mooring chain connection to obtain the mooring unit force response, and multiply the mooring force under different working conditions by the mooring unit force response to obtain the time-series mooring response under different working conditions; Based on the random wave spectrum, the Morrison equation is used to calculate the wave load on the wind turbine foundation, and the foundation motion response and hydrodynamic pressure distribution in each regular wave are obtained. The finite element analysis of the wind turbine foundation is carried out under various hydrodynamic pressure conditions to obtain the wave response under different conditions. The wave response is reconstructed into a time series wave response. The expression of the time series wave response is as follows: The time-series tower bottom load response, time-series mooring response, and time-series wave response of the same working condition are linearly superimposed to obtain the stress time history curve of the corresponding working condition; the rain flow count is performed on the stress time history curve, and the total fatigue damage of the working condition is obtained by combining it with the SN curve; The total fatigue damage of all working conditions within the target service time of the wind turbine foundation is weighted and calculated to obtain the fatigue damage of all working conditions. The expression of fatigue damage of all working conditions is as follows: Among them, σ(t) is the time series wave response, k n is the wave number, ε n is the phase angle, H(ω n ) is the amplitude-response transfer function, ω n is the wave frequency, Δω is the frequency interval, S ζ (ω n ) is the wave response spectrum, is the standard cosine wave amplitude; D is the fatigue damage under all working conditions, D i is the total fatigue damage of the i-th working condition, m is the number of working conditions, T is the target service time of the wind turbine foundation, T i is the time of the i-th working condition.

2. The offshore floating wind turbine foundation fatigue analysis method according to claim 1 is characterized in that: The tower bottom load unit force response includes F x 、F y 、F z 、M x 、M y 、M z Six-DOF unit force response, where F x 、F y 、F z are the unit forces in the X, Y, and XY directions applied to the rigid connection between the tower bottom and the column, respectively. x 、M y 、M z It is the unit moment in the X, Y and XY directions applied to the rigid connection between the tower base and the column.

3. The offshore floating wind turbine foundation fatigue analysis method according to claim 1, characterized in that: The mooring unit force response includes the F x _j, F y _j, F z _j three-degree-of-freedom unit force response, where F x _j, F y _j, F z _j are the unit forces in the X, Y, and XY directions applied at the j-th mooring chain connection.

4. The offshore floating wind turbine foundation fatigue analysis method according to claim 1, characterized in that: The wave response includes wave responses in X, Y, and XY directions.

5. An electronic device, characterized in that: include: one or more processors; A memory having one or more programs stored thereon, which, when the one or more programs are executed by the one or more processors, enables the one or more processors to implement the steps of the method according to any one of claims 1 to 4.

6. A computer-readable storage medium, characterized in that: The computer program is stored therein, and when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

Images