A method and device for large floating wind turbine strong nonlinear simulation

Abstract

The application provides a large floating wind turbine strong nonlinear simulation method and device, wherein the method comprises the following steps: according to the model parameters of a target floating wind turbine, the target floating wind turbine is divided into multiple body structures to construct a multi-body model containing multiple degrees of freedom, and the whole machine load and motion transmission path are established; the aerodynamic load input of each body structure is calculated, and the nonlinear dynamic response of the blade is calculated according to the aerodynamic load input of each body structure; the nonlinear dynamic response of the blade is converted to the whole coordinate system and input into the multi-body dynamic model of the whole machine through the coordinate transformation relationship, the generalized active force and the generalized inertia force of each body structure in the target floating wind turbine are calculated, and the motion response of each body structure in the target floating wind turbine is obtained by simultaneous solution. Through the above scheme, the motion response of each body structure of the target floating wind turbine can be accurately determined, so that the running state of the floating wind turbine in the deep sea complex environment can be accurately evaluated.

Description

Technical Field

[0001] This application belongs to the field of integrated simulation technology for offshore wind power equipment, and in particular relates to a simulation method and device suitable for strong nonlinearity of large floating wind turbines. Background Technology

[0002] As offshore wind power development gradually extends to deeper waters, floating wind turbines are an important development direction. To increase unit installed capacity and reduce the cost per kilowatt-hour, wind turbines are rapidly becoming larger, with single-unit power reaching 20MW and blade lengths exceeding 100 meters. These ultra-long, flexible blades typically employ lightweight designs, resulting in reduced stiffness and a tendency for large deformations and rotations, leading to significant geometric nonlinear effects and placing higher demands on the accuracy of aeroelastic calculations.

[0003] Furthermore, the complex wind, wave, and current environment in the deep sea brings about stronger unsteady aerodynamic and hydrodynamic coupling effects. Offshore wind fields exhibit non-uniform turbulent characteristics, with significant evolution and interaction of wind turbine wakes; the wave environment includes not only regular and random waves but also extreme waves, inducing strong nonlinear motion and coupled responses in the platform. Existing aerodynamic models are often based on blade element-momentum theory, which struggles to capture unsteady inflow and wake effects; most commonly used structural dynamics models assume small deformations, failing to accurately describe the nonlinear aeroelastic characteristics of long, flexible blades; and in hydrodynamic analysis, frequency domain potential flow theory lacks accuracy under extreme sea conditions, making it difficult to simultaneously consider both engineering efficiency and a true reflection of nonlinear responses.

[0004] There is currently no effective solution for controlling multi-field coupling effects and improving the accuracy of motion response at various structural points of the target floating wind turbine. Summary of the Invention

[0005] The purpose of this application is to provide a simulation method and device for strong nonlinearity of large floating wind turbines, which can improve the accuracy of motion response at various structural parts of the target floating wind turbine.

[0006] This application provides a simulation method and apparatus for highly nonlinear simulation of large floating wind turbines, which is implemented as follows: A simulation method for highly nonlinear large-scale floating wind turbines, the method comprising: Obtain the model parameters of the target floating wind turbine, wherein the model parameters include at least one of the following: shape parameters and mass parameters; The target floating wind turbine is divided into multiple body structures according to the model parameters to construct a multibody model with multiple degrees of freedom, and to establish the overall load and motion transmission path. The multiple body structures include at least one of the following: blades, rotor, nacelle, main shaft, yaw bearing, tower, and floating platform. Based on the relative positional relationship of each structure in the target floating wind turbine, a local coordinate system is established for each structure, and the origin of the tower bottom is taken as the reference origin of the overall coordinate system. The coordinate transformation relationship of all structures of the whole machine from the local to the overall coordinate system is established. Calculate the aerodynamic load input for each body structure, and calculate the nonlinear dynamic response of the blade based on the aerodynamic load input for each body structure; By using the coordinate transformation relationship, the nonlinear dynamic response of the blades is transformed into the global coordinate system and input into the multibody dynamic model of the whole machine. The generalized active force and generalized inertial force of each body structure in the target floating wind turbine are calculated, and the motion response at each body structure of the target floating wind turbine is obtained by solving them simultaneously.

[0007] In one implementation, calculating the aerodynamic load inputs for each structural element includes: Obtain the wind condition parameters of the target floating wind turbine operating area; Establish a free vortex wake enhanced vortex lattice aerodynamic model for the blades; Based on the free vortex wake enhanced vortex lattice aerodynamic model of the blades and the wind condition parameters, the unsteady aerodynamic loads of the three blades of the wind turbine are calculated respectively. The unsteady aerodynamic load coordinates of the three blades are transformed to the wind turbine coordinate system and superimposed to obtain the aerodynamic load of the wind turbine. The aerodynamic load of the wind turbine is sequentially transformed onto the coordinates of each structural component, serving as the aerodynamic load input for each component.

[0008] In one embodiment, the nonlinear dynamic response of the blade is calculated based on the aerodynamic load input of each structural element, including: Obtain the structural parameters of the blade; Based on the nonlinear dynamic model of the long flexible blade and the structural parameters of the blade, the nonlinear control equations of the blade are constructed. Based on the aforementioned nonlinear control equations, and combined with the unsteady aerodynamic loads on the blades as well as the gravity and inertial force loads on the blades, the nonlinear dynamic response of the blades is obtained by iterative solution.

[0009] In one implementation, a free vortex wake-enhanced vortex lattice aerodynamic model of the blade is established, including: Based on the evolution and interaction of the blade attached vortex and wake vortex, the induced velocity generated by the vortex at the blade control point is calculated. ; The free-flowing air and the rigid body velocity of the target floating wind turbine in the global coordinate system are transformed to the blade coordinate system, and the free-flowing air velocity is used as the basis for this transformation. Wind turbine rigid body motion velocity and blade elastic deformation rate The total velocity at the control point is obtained: ; in, The total speed at the control point, For free-flow wind speed, The velocity of the rigid body of the wind turbine. The elastic deformation rate of the blade, For induced velocity, i represents the i-th control point of the vortex lattice on the blade lifting surface; Based on the impenetrable boundary assumption, the aerodynamic coefficient matrix of the influence of attached vortex and wake vortex on the induced velocity of the control point is determined. Based on the aerodynamic coefficient matrix, establish the velocity equation at the control point, and calculate the attached vortex intensity based on the velocity equation. ; Calculate the unsteady aerodynamic lift and unsteady aerodynamic drag of the blades using the following formulas: ; ; in, For unsteady aerodynamic lift of the blades, For unsteady aerodynamic drag of the blades, air density, For the airfoil chord, The aerodynamic lift coefficient includes viscosity. The aerodynamic drag coefficient includes viscosity. The length of the unit containing the airfoil. Based on the strength of the attached vortex The calculated unsteady induced drag is given by j, which represents the j-th wake vortex that detaches from the trailing edge of the blade.

[0010] In one embodiment, obtaining the viscous aerodynamic lift coefficient and the viscous aerodynamic drag coefficient includes: Calculate the effective angle of attack of the airfoil using the following formula: ; ; in, For the effective angle of attack of the airfoil, It is the effect of wind turbine pitch control on angle of attack. For unsteady induced lift of the blades, The lift coefficient of the airfoil; By matching the effective angle of attack of the airfoil with the two-dimensional airfoil wind tunnel data through a lookup table, the viscous aerodynamic lift coefficient and the viscous aerodynamic drag coefficient are obtained.

[0011] In one embodiment, the nonlinear dynamic response of the blade is obtained iteratively by combining the nonlinear control equations with the unsteady aerodynamic loads of the blade and the gravity and inertial force loads of the blade, including: Based on the blade's structural parameters, the tangential stiffness matrix of the blade structure is established by deriving the second-order transverse and longitudinal displacement fields and Green strain: ; in, Here is the tangent stiffness matrix. For the linear stiffness component, This refers to the portion with large deformation stiffness. This is the centrifugal tempering part; Obtain the mass parameters of the blade, and determine the mass matrix and structural damping matrix of the blade based on the mass parameters; The external load is obtained by adding the aerodynamic load to the blade's gravity load and inertial force load. Based on the external load, tangent stiffness matrix, mass matrix, and structural damping matrix, the nonlinear governing equations for the blades describing large structural deformations are established: ; in, This represents the blade displacement acceleration. Indicates the blade displacement velocity. This represents the increment of blade displacement. For external loads, Here is the tangent stiffness matrix. For the quality matrix, Here is the structural damping matrix; The servo coordinate system is derived using the co-rotation coordinate method; Based on the servo coordinate system, establish the co-rotation transformation relationship between the internal element coordinate system and the global coordinate system of the blade to realize the description of the large rotation of the blade: ; in, This represents the moving coordinate system, which is the coordinate transformation matrix from the unit coordinate system to the global coordinate system. This represents the tangent stiffness matrix of the blade element; Within the framework of the modified Lagrange method, time-step integration is performed using the nonlinear Newmark-β method, and the nonlinear dynamic response of the blade is solved iteratively at each time step using the Newton-Raphson method.

[0012] In one embodiment, after calculating the aerodynamic load inputs for each structural element, the method further includes: Obtain wave parameters; Based on the higher-order spectral model and the wave parameters, the irregular incident waves acting on the floating platform are calculated. The nonlinear wave hydrodynamics of the floating platform under the wave-object interaction in the inner domain is calculated based on the time-domain fully nonlinear potential flow theory and the higher-order boundary element method.

[0013] In one implementation, based on a higher-order spectral model and the wave parameters, the irregular incident waves acting on the floating platform are calculated, including: The nonlinear free-surface boundary conditions are solved using the pseudospectral method to generate an incident wave field containing modulation instability: ; ; in, Vertical velocity, For convection terms, This is the static pressure recovery item. For dynamic pressure, It is a nonlinear coupling term. For the incident wave field; The incident wave field is reconstructed in three dimensions to obtain the horizontal velocity of the incident wave. and horizontal speed , ; ; in, The horizontal velocity of the incident wave, It is a horizontal position vector. For horizontal velocity, This is a two-dimensional inverse Fourier transform. The horizontal wavenumber vector, , To calculate the hyperbolic tangent, It is a three-dimensional velocity potential spectrum. For the incident wave velocity field; The incident wave velocity field is interpolated to the inner domain boundary to determine the influence of the nonlinear evolution of the outer domain wave field on the nonlinear hydrodynamics of the inner domain.

[0014] In one implementation, the nonlinear wave hydrodynamics of the floating platform under the wave-object interaction in the inner domain is calculated based on the time-domain fully nonlinear potential flow theory and the higher-order boundary element method, including: Establish the boundary integral equation: ; in, Let P be the velocity potential at the field point. The self-influence of the velocity potential at point P. For the Rankine Green's function, For the boundary velocity potential distribution, For boundary normal velocity perturbation, For boundary tangential velocity perturbation, Indicates the fixed angle factor. Indicates the field point. Represents velocity potential, Indicates the source point, Represents the Green's function. Represents the normal derivative along the boundary. Indicates the integral boundary where the source point is located; Discretize the boundary integral equation using the higher-order boundary element method; The scattering potential is calculated using the boundary integral equation. ; Through scattering potential Calculate the total velocity potential ; Through total velocity potential The acceleration potential is calculated. : ; in, For acceleration potential, The total velocity potential, This refers to the normal acceleration caused by the motion of the floating platform. This refers to the interaction between the motion of the floating platform and the fluid velocity gradient. For reference frame rotation correction, This represents the actual velocity of the fluid particles. For the translational acceleration of the floating platform, The rotational speed of the floating platform. The rotational acceleration of the floating platform, Let be the position vector of the floating platform surface. Let be the unit normal vector of the floating platform; Based on the acceleration potential, calculate the nonlinear wave hydrodynamics of the floating platform. : ; in, This represents the nonlinear wave hydrodynamics of a floating platform. air density, The unit normal vector representing the boundary of the integral. Indicates the integral boundary where the field point is located. This refers to the static pressure distribution caused by fluid gravity. The pressure term represents the conversion of fluid kinetic energy.

[0015] In one embodiment, after calculating the nonlinear wave hydrodynamics of the floating platform under the wave-object interaction in the inner domain based on the time-domain fully nonlinear potential flow theory and the higher-order boundary element method, the method further includes: Obtain the velocity and acceleration of the floating platform at the previous time step; The motion velocity and acceleration of the floating platform in the previous time step are transformed to the origin at the bottom of the tower through coordinate transformation, so as to calculate the motion response of each body structure of the target floating wind turbine under the motion of the floating platform according to the multibody dynamics equations of the current time step. The total load at the bottom of the tower, calculated at the current time step considering aerodynamic loads, inertial loads, gravity loads, and damping loads, is transformed to the platform reference point. The nonlinear wave hydrodynamics, viscous damping force, and mooring load of the floating platform are input into the platform's coupled motion equations to calculate the floating platform's motion response.

[0016] A simulation device for strong nonlinearity of large floating wind turbines, comprising: The acquisition module is used to acquire model parameters of the target floating wind turbine, wherein the model parameters include at least one of the following: shape parameters and mass parameters; The construction module is used to divide the target floating wind turbine into multiple body structures according to the model parameters, so as to construct a multibody model containing multiple degrees of freedom and establish the whole machine load and motion transmission path. The multiple body structures include at least one of the following: blades, wind turbine, nacelle, main shaft, yaw bearing, tower, and floating platform. A module is established to establish a local coordinate system for each structure based on the relative positional relationship of each structure in the target floating wind turbine, and to establish the coordinate transformation relationship of all structures of the whole machine from the local to the global coordinate system with the origin of the tower bottom as the reference origin of the global coordinate system. The first calculation module is used to calculate the aerodynamic load input of each body structure and to calculate the nonlinear dynamic response of the blade based on the aerodynamic load input of each body structure. The second calculation module is used to transform the nonlinear dynamic response of the blades to the global coordinate system through the coordinate transformation relationship and input it into the multibody dynamic model of the whole machine. It calculates the generalized active force and generalized inertial force of each body structure in the target floating wind turbine, and solves them simultaneously to obtain the motion response of each body structure of the target floating wind turbine.

[0017] A terminal device includes a processor and a memory for storing processor-executable instructions, wherein the processor implements the steps of the method described above when executing the instructions.

[0018] A computer-readable storage medium having a computer program / instructions stored thereon, which, when executed by a processor, implement the steps of the above-described method.

[0019] A computer program product includes a computer program / instructions that, when executed by a processor, implement the steps of the above-described method.

[0020] The proposed method for strong nonlinear simulation of large floating wind turbines divides the target floating wind turbine into multiple body structures based on its model parameters to construct a multibody model with multiple degrees of freedom, and establishes the overall load and motion transmission paths. Based on the relative positional relationships of each body structure, a local coordinate system is established for each body structure, with the origin at the tower base as the reference origin of the global coordinate system. A coordinate transformation relationship is established for all body structures from the local to the global coordinate system. The aerodynamic load input for each body structure is calculated, and the nonlinear dynamic response of the blades is calculated based on this input. Through the coordinate transformation relationship, the nonlinear dynamic response of the blades is transformed to the global coordinate system and input into the multibody dynamic model of the entire turbine. The generalized active force and generalized inertial force of each body structure in the target floating wind turbine are calculated, and then solved simultaneously to obtain the motion response at each body structure of the target floating wind turbine. The multibody dynamics model of the floating wind turbine established in this example can realize the bidirectional coupling and transmission of the aerodynamic and hydrodynamic responses of the floating wind turbine between the upper unit and the lower platform. By accurately calculating the generalized inertial force under multibody coupling through the motion velocity and acceleration of each body structure, it can effectively analyze the strong nonlinear effects under the combined action of the multibody dynamic coupling of the floating wind turbine itself and the external environment. Thus, it can accurately determine the motion response of each body structure of the target floating wind turbine, so as to accurately assess the operating status of the floating wind turbine in the complex environment of the deep sea. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart of one embodiment of the strong nonlinear simulation method for large floating wind turbines provided in this application; Figure 2 This invention relates to a flowchart of a strongly nonlinear simulation method for floating wind turbines. Figure 3 This is a flowchart of the simulation method for unsteady aerodynamic models of blades involved in this invention; Figure 4 This is a flowchart of the blade nonlinear dynamic model simulation method involved in this invention; Figure 5 This is a flowchart of the nonlinear hydrodynamic model simulation method for floating platforms involved in this invention; Figure 6 This is a hardware structure block diagram of an electronic device suitable for a strongly nonlinear simulation method for large floating wind turbines, as provided in this application. Figure 7 This is a schematic diagram of the module structure of one embodiment of the simulation device for strong nonlinearity of large floating wind turbines provided in this application. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0024] This paper proposes a strong nonlinear simulation method for large floating wind turbines. By constructing an integrated simulation model of the floating wind turbine, which integrates unsteady aerodynamics, time-domain fully nonlinear hydrodynamics, long flexible blade elasticity, multibody structure coupling, and servo control, the method fully considers the multibody dynamic coupling of the wind turbine itself and the strong nonlinear effects under the influence of the external environment. While meeting the requirements of engineering calculation efficiency, the method achieves high-precision simulation of the response characteristics of the floating wind turbine, ensuring the reliable design and safe operation of large floating wind turbines in deep-sea areas.

[0025] Figure 1 This is a flowchart illustrating one embodiment of a simulation method for highly nonlinear large-scale floating wind turbines provided in this application. While this application provides method operation steps or apparatus structures as shown in the following embodiments or accompanying drawings, more or fewer operation steps or module units may be included in the method or apparatus based on conventional or non-inventive effort. In steps or structures where there is no logically necessary causal relationship, the execution order of these steps or the module structure of the apparatus is not limited to the execution order or module structure described in the embodiments and accompanying drawings of this application. When the method or module structure is applied in actual devices or end products, it can be executed sequentially or in parallel according to the method or module structure shown in the embodiments or accompanying drawings (e.g., in a parallel processor or multi-threaded processing environment, or even a distributed processing environment).

[0026] Specifically, such as Figure 1 As shown, the above-mentioned simulation method for highly nonlinear large-scale floating wind turbines may include the following steps: Step 101: Obtain the model parameters of the target floating wind turbine, wherein the model parameters include at least one of the following: shape parameters and mass parameters; Among these, strong nonlinearity involves using a multibody dynamics model to describe large-scale motion, while simultaneously employing nonlinear beam theory to solve the nonlinear dynamics of wind turbine blades, free vortex wake-enhanced vortex lattice theory to solve the unsteady aerodynamics of wind turbines, and time-domain nonlinear hydrodynamic theory to solve the nonlinear hydrodynamics of floating platforms. This approach can effectively improve the simulation accuracy of large floating wind turbines while maintaining moderate efficiency. In practical implementation, for example, in floating wind turbine simulations, environmental parameters can be derived from hydrological and meteorological statistics of the target sea area, while model parameters can be derived from preliminary wind turbine structural data designed using professional CAD / CAE software based on the target sea area, turbine selection, platform type, and other relevant factors.

[0027] Step 102: Divide the target floating wind turbine into multiple body structures according to the model parameters to construct a multibody model with multiple degrees of freedom, and establish the whole machine load and motion transmission path. The multiple body structures include at least one of the following: blades, rotor, nacelle, main shaft, yaw bearing, tower, and floating platform. The division of the target floating wind turbine into multiple structural units can be based on the actual structure of the floating wind turbine.

[0028] Step 103: Based on the relative positional relationship of each structure in the target floating wind turbine, establish the local coordinate system of each structure, and take the origin of the tower bottom as the reference origin of the overall coordinate system to establish the coordinate transformation relationship of all structures of the whole machine from the local to the overall coordinate system. Step 104: Calculate the aerodynamic load input for each body structure, and calculate the nonlinear dynamic response of the blade based on the aerodynamic load input for each body structure; Step 105: Through the coordinate transformation relationship, the nonlinear dynamic response of the blade is transformed into the global coordinate system and input into the multibody dynamic model of the whole machine. The generalized active force and generalized inertial force of each body structure in the target floating wind turbine are calculated, and the motion response at each body structure of the target floating wind turbine is obtained by solving them simultaneously.

[0029] The above multibody dynamics model is based on multibody dynamics theory. According to the 31 degrees of freedom of the multibody structure of the floating wind turbine (3 blades × 6, floating platform × 6, tower × 4, yaw × 1, low-speed axis × 1, high-speed axis × 1), the yaw velocity, yaw angular velocity and angular momentum of each body structure are solved separately. The generalized active force and generalized inertial force are derived in conjunction with the external load. The multibody motion control equations are then constructed to obtain the final multibody dynamics model.

[0030] Specifically, the aerodynamic load input for each structural element can be calculated as follows: S1: Obtain the wind condition parameters of the target floating wind turbine operating area; S2: Establish a free vortex wake enhanced vortex grid aerodynamic model for the blades; S3: Based on the free vortex wake enhanced vortex grid aerodynamic model of the blades and the wind condition parameters, calculate the unsteady aerodynamic loads of the three blades of the wind turbine respectively; S4: Transform the coordinates of the unsteady aerodynamic loads of the three blades to the wind turbine coordinate system and superimpose them to obtain the aerodynamic loads of the wind turbine. S5: The aerodynamic load of the wind turbine is sequentially transformed to the coordinates of each structural body, serving as the aerodynamic load input for each structural body.

[0031] Accordingly, calculating the nonlinear dynamic response of the blades based on the aerodynamic load inputs of each structural element can include: S1: Obtain the structural parameters of the blade; The blade structural parameters can be obtained from external CAE tools, such as ABQUS / VABS / BECAS. Specifically, after the blade design is completed, its structural parameters are input into this model and subsequent nonlinear dynamic analysis is carried out by designing the composite material layup of the blade in an external program.

[0032] S2: Based on the nonlinear dynamic model of the long flexible blade and the structural parameters of the blade, construct the nonlinear control equations of the blade; Blade nonlinearity refers to geometric nonlinearity. In this example, by considering the nonlinear displacement fields in the transverse and longitudinal directions and the plane Green strain, the linear Euler-Bernoulli beam model is extended into a nonlinear beam model, thereby constructing a nonlinear dynamic model of the blade to analyze the nonlinear dynamic characteristics such as the large deformation of the long flexible blade.

[0033] S3: Based on the aforementioned nonlinear control equations, and combined with the unsteady aerodynamic loads on the blades and the gravity and inertial force loads on the blades, the nonlinear dynamic response of the blades is obtained by iterative solution.

[0034] Specifically, based on the aforementioned nonlinear control equations, and combining the unsteady aerodynamic loads on the blades with the gravity and inertial force loads on the blades, the nonlinear dynamic response of the blades is obtained through iterative solution, which may include: S3-1: Based on the blade's structural parameters, the tangential stiffness matrix of the blade structure is established by deriving the second-order transverse and longitudinal displacement fields and Green strain. : ; in, Here is the tangent stiffness matrix. For the linear stiffness component, This refers to the portion with large deformation stiffness. This is the centrifugal tempering part; S3-2: Obtain the mass parameters of the blade, and determine the mass matrix and structural damping matrix of the blade based on the mass parameters of the blade; S3-3: The external load is obtained by adding the aerodynamic load to the blade's gravity load and inertial force load; S3-4: Based on the external load, tangent stiffness matrix, mass matrix, and structural damping matrix, establish the nonlinear governing equations for the blade to describe large structural deformations: ; in, This represents the blade displacement acceleration. Indicates the blade displacement velocity. This represents the increment of blade displacement. For external loads, Here is the tangent stiffness matrix. For the quality matrix, Here is the structural damping matrix; S3-5: Deriving the follower coordinate system using the co-rotation coordinate method; S3-6: Establish the co-rotation transformation relationship between the internal element coordinate system and the global coordinate system of the blade based on the follower coordinate system to realize the description of the large rotation of the blade: ; in, This represents the moving coordinate system, which is the coordinate transformation matrix from the unit coordinate system to the global coordinate system. This represents the tangent stiffness matrix of the blade element; S3-7: Within the framework of the modified Lagrange method, time-step integration is performed using the nonlinear Newmark-β method, and the nonlinear dynamic response of the blade is solved iteratively at each time step using the Newton-Raphson method.

[0035] That is, by locally coupling the nonlinear model of the current blade, the calculation accuracy of the blade response is improved. The blade response changes the blade node position, thereby changing the aerodynamic calculation. The aerodynamic force is then input into the multibody dynamics model, which indirectly affects the overall analysis of the wind turbine.

[0036] In practical implementation, the free vortex wake-enhanced vortex lattice aerodynamic model of the blade can be established as follows: S1: Calculate the induced velocity generated by the vortex at the blade control point based on the evolution and interaction of the blade attached vortex and wake vortex. ; S2: Transform the free-flowing air and the rigid body motion velocity of the target floating wind turbine in the global coordinate system to the blade coordinate system, and use the free-flowing air velocity... Wind turbine rigid body motion velocity and blade elastic deformation rate The total velocity at the control point is obtained: ; in, The total speed at the control point, For free-flow wind speed, The velocity of the rigid body of the wind turbine. The elastic deformation rate of the blade, For induced velocity; S3: Based on the impenetrable boundary assumption, determine the aerodynamic coefficient matrix of the influence of attached vortex and wake vortex on the induced velocity of the control point; S4: Establish the velocity equation at the control point based on the aerodynamic coefficient matrix, and calculate the attached vortex intensity based on the velocity equation. ; S5: Calculate the unsteady aerodynamic lift and unsteady aerodynamic drag of the blades using the following formulas: ; ; in, For unsteady aerodynamic lift of the blades, For unsteady aerodynamic drag of the blades, air density, For the airfoil chord, The aerodynamic lift coefficient includes viscosity. The aerodynamic drag coefficient includes viscosity. The length of the unit containing the airfoil. Based on the strength of the attached vortex The calculated unsteady induced drag is given by i, which represents the i-th control point or i-th structure or i-th aerodynamic unit of the blade lifting surface vortex grid, and j, which represents the j-th wake vortex or j-th wake vortex unit that detaches from the trailing edge of the blade.

[0037] Since the three blades have different initial installation orientations, the total velocity of the blade control points varies at different times. According to the above formula, the different lift / drag of the three blades is calculated at each time. The results of the three blades are superimposed to obtain the unsteady aerodynamic load (i.e. lift and drag) of the wind turbine.

[0038] The free vortex wake lattice model can consider the dynamic evolution of the wind turbine wake and its impact on the aerodynamic load of the wind turbine. Furthermore, the vortex lattice method can more precisely describe the evolution of attached vortices on the blade surface, making it more suitable for analyzing non-uniform flow and highly unsteady wind conditions. Meanwhile, traditional free vortex wake models, based on potential flow theory, cannot account for viscous effects. In this example, by consulting two-dimensional airfoil wind tunnel data, viscous effects can be incorporated.

[0039] In practice, the viscous aerodynamic lift coefficient and viscous drag coefficient can be obtained as follows: The effective angle of attack of the airfoil can be calculated using the following formula: ; in, For the effective angle of attack of the airfoil, It is the effect of wind turbine pitch control on angle of attack. For unsteady induced lift of the blades, The airfoil lift coefficient is determined by the effective angle of attack of the airfoil. Then, the two-dimensional airfoil wind tunnel data is matched by a lookup table to obtain the viscous aerodynamic lift coefficient and the viscous aerodynamic drag coefficient.

[0040] In practical implementation, after calculating the aerodynamic load input of each structure, it may also include: obtaining wave parameters; calculating irregular incident waves acting on the floating platform based on the higher-order spectral model and the wave parameters; and calculating the nonlinear wave hydrodynamics of the floating platform under the interaction of wave and object in the inner domain based on the time-domain fully nonlinear potential flow theory and the higher-order boundary element method.

[0041] The wave parameters mentioned above can be obtained from the hydrological and meteorological data of the target sea area. Time-domain fully nonlinear hydrodynamics refers to updating the position of the object surface and the free water surface at each moment to realize the real-time tracking of fluid particles on the free water surface in order to solve the arbitrary motion of the object under the action of wave hydrodynamics.

[0042] Specifically, based on the higher-order spectral model and the wave parameters, calculating the irregular incident waves acting on the floating platform can include: S1: Solve the nonlinear free surface boundary conditions using the pseudospectral method to generate an incident wave field containing modulation instability: ; in, Vertical velocity, For convection terms, This is the static pressure recovery item. For dynamic pressure, It is a nonlinear coupling term. For the incident wave field; S2: Perform three-dimensional reconstruction of the incident wave field to obtain the incident wave horizontal velocity and horizontal velocity. ; in, The horizontal velocity of the incident wave, It is a horizontal position vector. For horizontal velocity, This is a two-dimensional inverse Fourier transform. The horizontal wavenumber vector, , To calculate the hyperbolic tangent, It is a three-dimensional velocity potential spectrum. For the incident wave velocity field; S3: Interpolate the incident wave velocity field to the inner domain boundary to determine the influence of the nonlinear evolution of the outer domain wave field on the nonlinear hydrodynamics of the inner domain.

[0043] Specifically, the nonlinear wave hydrodynamics of the floating platform under the wave-object interaction in the inner domain, calculated based on the time-domain fully nonlinear potential flow theory and the higher-order boundary element method, can include: S1: Establish the boundary integral equation: ; in, Let P be the velocity potential at the field point. The self-influence of the velocity potential at point P. For the Rankine Green's function, For the boundary velocity potential distribution, For boundary normal velocity perturbation, For boundary tangential velocity perturbation, Indicates the fixed angle factor. Indicates the field point. Represents velocity potential, Indicates the source point, Represents the Green's function. Represents the normal derivative along the boundary. Indicates the integral boundary where the source point is located; S2: Discretize the boundary integral equation using the higher-order boundary element method; S3: Calculate the scattering potential using the boundary integral equation. ; S4: Through scattering potential Calculate the total velocity potential ; S5: Through the total velocity potential The acceleration potential is calculated. : ; in, For acceleration potential, The total velocity potential, This refers to the normal acceleration caused by the motion of the floating platform. This refers to the interaction between the motion of the floating platform and the fluid velocity gradient. For reference frame rotation correction, This represents the actual velocity of the fluid particles. For the translational acceleration of the floating platform, The rotational speed of the floating platform. The rotational acceleration of the floating platform, Let be the position vector of the floating platform surface. Let be the unit normal vector of the floating platform; S6: Based on the aforementioned acceleration potential Calculate the nonlinear wave hydrodynamics of the floating platform. : ; in, This represents the nonlinear wave hydrodynamics of a floating platform. air density, The unit normal vector representing the boundary of the integral. Indicates the integral boundary where the field point is located. This refers to the static pressure distribution caused by fluid gravity. The pressure term represents the conversion of fluid kinetic energy.

[0044] In implementation, after calculating the nonlinear wave hydrodynamics of the floating platform under the wave-object interaction in the inner domain based on the time-domain fully nonlinear potential flow theory and the higher-order boundary element method, the following steps may be included: obtaining the motion velocity and acceleration of the floating platform in the previous time step; transforming the motion velocity and acceleration of the floating platform in the previous time step to the origin at the bottom of the tower through coordinate transformation, so as to calculate the motion response of each body structure of the target floating wind turbine under the motion of the floating platform according to the multibody dynamics equations of the current time step; transforming the total load at the bottom of the tower, which considers aerodynamic loads, inertial loads, gravity loads and damping loads, to the platform reference point through coordinate transformation; and inputting the nonlinear wave hydrodynamics, viscous damping force and mooring load of the floating platform into the platform coupled motion equations to calculate the motion response of the floating platform.

[0045] The above method will be described below with reference to a specific embodiment. However, it should be noted that this specific embodiment is only for better illustration of this application and does not constitute an improper limitation of this application.

[0046] This example presents an integrated simulation method that considers the multi-field coupling effects of aerodynamics, hydrodynamics, structural dynamics, and servo control, and captures strong nonlinear characteristics. While ensuring computational efficiency, this method can improve the simulation accuracy of the operating state of floating wind turbines in complex wind and wave environments in deep seas, thus providing reliable support for the safe design and operation of large floating wind turbines.

[0047] This example presents a highly nonlinear simulation method suitable for large floating wind turbines: taking a horizontal-axis floating wind turbine as the object, a multi-body coupled framework for the entire machine is established. Based on the multibody dynamics method, the floating wind turbine is sequentially divided into multiple body structures: blades, rotor, nacelle, main shaft, yaw bearing, tower, and floating platform, establishing a multibody model with 31 degrees of freedom. Simultaneously, with the center point of the tower base as the origin of the global coordinate system, local coordinate systems for each body structure are defined. Then, the coordinate transformation relationship from each local coordinate system to the global coordinate system is established. Next, the yaw velocity, yaw angular velocity, and angular momentum of each body structure in the global coordinate system are calculated. Subsequently, the generalized active forces and generalized inertial forces of each body structure are calculated, and finally, the multibody dynamics equations of the floating wind turbine are superimposed to establish the multibody dynamics equations.

[0048] 1) Establishing a dynamic model for long, flexible blades can include: Based on the second-order Euler-Bernoulli beam and the corotational coordinate method, the tangential stiffness matrix of the blade is obtained by deriving the second-order transverse and longitudinal displacement fields, Green strain, and corotational coordinate transformation. And combined with the mass matrix of the blade Structural damping matrix and external loads Establish nonlinear control equations for blades that can describe large structural deformation and rotation. Furthermore, within the framework of the modified Lagrange method, time-step integration is performed using the nonlinear Newmark-β method, and the nonlinear dynamic response of the long flexible blade is obtained by iterative solution using the Newton-Raphson method at each time step. ; 2) Establish a free vortex wake-enhanced vortex grid unsteady aerodynamic model for wind turbine blades: The blade surface is discretized into a lifting surface vortex lattice. An attached vortex is placed at each vortex lattice control point, and detaches from the trailing edge as a wake vortex as the blade rotates. The induced velocities of the two types of vortices at the vortex lattice control points are calculated based on the Biot-Savart theorem, while simultaneously considering the free inflow velocity, the blade rigid body motion velocity, and the elastic deformation velocity. The total velocity at the control point is obtained by summing these values. Based on the impenetrable boundary assumption, the aerodynamic coefficient matrix of the influence of attached vortices and wake vortices on the induced velocity of the control point is derived. Establish the velocity equation at the control point. Solve for the strength of attached vortices Then, based on the strength of the attached vortex... Calculation of unsteady induced lift of blades using Joukowski extended theory and induced resistance And based on induced aerodynamic lift Calculate the effective angle of attack Then, the aerodynamic lift and drag coefficients (considering viscosity) are obtained by looking up the effective angle of attack table (two-dimensional wind tunnel airfoil data), and the unsteady aerodynamic lift is calculated. and viscous components of aerodynamic drag This will induce aerodynamic drag. With viscous aerodynamic drag Adding them together gives the complete aerodynamic drag. In this process, the blade wake motion can be updated based on the fourth-order Runge-Kutta method.

[0049] 3) Establish a nonlinear hydrodynamic model for the floating platform: The wave field around the floating platform is divided into an outer domain and an inner domain. The outer domain describes the nonlinear wave evolution based on a higher-order spectral method. This is achieved by employing a pseudospectral method to calculate the nonlinear free surface conditions, generating incident waves containing modulation instability. The numerical solution of the incident wave is transferred to the inner domain using three-dimensional reconstruction and interpolation. The inner domain describes the nonlinear hydrodynamics under wave-object interaction based on the time-domain fully nonlinear potential flow theory. By using a Rankine source as the Green's function, the boundary integral equation is derived using Green's second theorem and discretized using the higher-order boundary element method. Then, the total velocity potential is calculated by incident-scatter separation. Incident potential Directly input the higher-order spectral numerical solution, scattering potential The boundary integral equations were solved and the instantaneous free surface was updated using the hybrid Euler-Lagrange method. Finally, the nonlinear hydrodynamics were indirectly calculated using the virtual function method. In this process, the fourth-order Runge-Kutta method can be used for time stepping, and the spring mesh method can be used to ensure the stability of the free surface mesh.

[0050] Among them, the virtual function method introduces virtual variables and obtains nonlinear hydrodynamics by solving the boundary integral equation containing virtual functions. This method avoids directly solving the time derivative of the velocity potential.

[0051] In practical implementation, the coordinate transformation relationship between the overall coordinate system and the blade coordinate system of the floating wind turbine can be used to transform the previous time step. The rigid body motion and elastic deformation of the floating wind turbine (initially zero) are transformed into the local coordinate system of the blades, and then the current blade node positions are updated. Alternatively, based on the coordinate transformation relationship between the global coordinate system and the blade coordinate system of the floating wind turbine, the coordinates from the previous time step can be used to update the coordinates. The free-flowing air, rigid body velocity, and elastic deformation velocity defined in the global coordinate system are transformed to the local coordinate system of the blade. Furthermore, the free-flowing air, rigid body velocity, and elastic deformation velocity at the blade nodes in the local coordinate system can be interpolated to the vortex grid control points and input into the wind turbine blade free vortex wake-enhanced vortex grid unsteady aerodynamic model. Combined with vortex-induced velocities, the current time step is calculated. Unsteady aerodynamic loads in the blade coordinate system are interpolated back to the blade nodes.

[0052] In one implementation, the blade stiffness and mass matrices can be derived using the blade structural parameters based on a long flexible blade dynamics model, establishing the nonlinear control equations for the long flexible blade. Since the current aerodynamic load, in addition to its own unsteady effects, already includes the blade's rigid body motion and elastic deformation, the unsteady aerodynamic loads at the current blade nodes can be directly input to the corresponding nodes of the long flexible blade dynamics model to account for aeroelastic coupling effects. Then, the gravity and inertial loads at each blade node are calculated and superimposed with the unsteady aerodynamic forces as the external load inputs to the blade's nonlinear control equations; subsequently, the current time step is iteratively solved. The nonlinear motion and elastic deformation of the blade in the local coordinate system are analyzed and output in the global coordinate system through inverse coordinate transformation; the current time step is then displayed. The unsteady aerodynamic loads of the three blades are respectively superimposed on the hub coordinate system to obtain the aerodynamic loads of the wind turbine. Then, based on the coordinate transformation relationship of the entire floating wind turbine, the aerodynamic loads of the wind turbine are sequentially transformed onto various structural bodies such as the nacelle and yaw axis. Finally, based on the multibody dynamics equations of the floating wind turbine, the generalized active forces and generalized inertial forces of each structural body are derived to solve for the current moment. The output is the motion response of each structure.

[0053] In implementation, wave surface parameter files can be pre-calculated using the shape and mass parameters of the floating wind turbine platform. Then, wave hydrodynamics at the platform reference point are calculated based on the nonlinear hydrodynamic model of the floating platform, and the second-order viscous damping force of the platform is calculated using the viscous damping coefficient obtained from platform pool tests or CFD simulations. Next, the mooring load of the floating platform is calculated using the mooring model. Subsequently, the wind turbine aerodynamic load and the platform mooring load are transferred to the platform reference point through coordinate transformation.

[0054] Furthermore, the unsteady aerodynamic forces of the wind turbine, the nonlinear wave hydrodynamic forces of the platform, the second-order damping forces of the platform, and the mooring loads of the platform are superimposed to obtain the total external load, which is then input into the coupled motion equations of the floating platform. The current time step is obtained by solving the equations using the fourth-order Runge-Kutta method. The acceleration, velocity, and displacement of the floating platform are output; the current time step is then calculated using the coordinate transformation relationship between the floating platform reference point and the mooring module. The acceleration, velocity, and displacement of the floating platform are transferred to the mooring model as the state input for the mooring load calculation in the next time step; the coordinate transformation relationship between the floating platform reference point and the origin of the wind turbine tower is used to transform the current time step... The acceleration, velocity, and displacement of the floating platform are converted to the origin at the bottom of the floating wind turbine tower, and then the motion response of the floating platform is input into the multibody dynamics equation of the whole machine to couple to the calculation of the dynamic response of the whole machine in the next time step; further, the above coupling calculation process is repeated until the calculation time ends.

[0055] In the example above, the nonlinear dynamic model of the blade was derived based on the nonlinear Euler-Bernoulli beam and the co-rotation coordinate method. It can take into account nonlinear deformation behaviors such as large deformation and large rotation in the blade motion response, has medium accuracy and high computational efficiency, and is suitable for efficient nonlinear dynamic response analysis of long and flexible wind turbine blades.

[0056] Specifically, this example provides a simulation method for highly nonlinear large-scale floating wind turbines, which may include the following steps: Step 1: Obtain the model parameters such as shape and mass of the target floating wind turbine. Based on the multibody dynamics method, divide the floating wind turbine into multiple body structures such as blades, rotor, nacelle, main shaft, yaw bearing, tower, and floating platform. Construct a multibody model with 31 degrees of freedom and establish the load and motion transmission path of the whole machine. Step 2: Based on the relative positional relationship of each structure of the floating wind turbine, establish the local coordinate system of each structure, and take the origin of the tower bottom as the reference origin (O) of the overall coordinate system to establish the coordinate transformation relationship of all structures of the whole machine from the local to the overall coordinate system; Step 3: Calculate the partial velocities of each structure in the global coordinate system. angular velocity and angular momentum Then, calculate the generalized active forces of each structure. and generalized inertial force Then, the multibody dynamics equations of the floating wind turbine are established by superimposing these equations: .

[0057] Step 4: By solving the above multibody dynamics equations, the motion response of each part of the target floating wind turbine structure is obtained.

[0058] Solving the above multibody dynamics equations yields the motion response at each structural point of the target floating wind turbine, as follows: Figure 2As shown, a coupled multibody dynamics model of a floating wind turbine is included. This model is associated with a coupling transfer module to obtain the nonlinear hydrodynamic loads and motion responses of the corrosion platform, as well as the mooring loads. This coupled multibody dynamics model can include: main shaft response, rotor response, yaw response, tower response, startup load, elastic deformation of long flexible blades, airfoil startup performance correction, inflow wind model, and servo system. Based on this, solving the above multibody dynamics equations yields the motion responses at various structural points of the target floating wind turbine, which may include: S1: Based on the wind conditions in the environment, the blade airfoil, and the state parameters such as the wind turbine's motion response and elastic deformation, calculate the unsteady aerodynamic load on the blade using the free vortex wake-enhanced aerodynamic model.

[0059] Specifically, it can be like Figure 3 As shown, a blade lifting surface model is constructed, the aerodynamic state information of the blade at the previous moment is obtained, the positions of the blade airfoil and wake vortex grid at the current moment are calculated, the intensity of the blade's attached vortex and wake vortex at the current moment is calculated, and then the inflow velocity at the blade vortex grid control point at the current moment is obtained. Further correction iterations are then performed. Specifically, the correction iterations may include: calculating the unsteady induced aerodynamic forces of the blade based on the Joukowski extended theory, calculating the effective angle of attack of the blade under unsteady conditions, obtaining the lift and drag coefficients (considering viscosity) from a table based on the effective angle of attack, and other unsteady engineering correction models; calculating the blade's induced aerodynamic drag and induced aerodynamic torque, and then calculating the blade's aerodynamic lift, aerodynamic drag, and aerodynamic torque considering viscosity to complete the correction iterations. Finally, it is determined whether it is the final time; if not, the process proceeds according to the time step, and the aerodynamic state information of the blade at the previous moment is obtained.

[0060] In implementation, based on environmental wind conditions, blade airfoil, and state parameters such as wind turbine motion response and elastic deformation, the calculation of unsteady aerodynamic loads on the blades using the free vortex wake-enhanced aerodynamic model can include: S.1.1: Consider the evolution and mutual influence of the blade attached vortex (at the control point of the lifting surface vortex grid) and the wake vortex (detached from the trailing edge of the blade), and calculate the induced velocity of the vortex on the blade control point during this process. ; S.1.2: Transform the free-flowing air and the rigid body motion velocity of the floating fan in the global coordinate system to the blade coordinate system, by combining the free-flowing air velocity... Wind turbine rigid body motion velocity and blade elastic deformation rate The total velocity at the control point can be obtained using the following formula: ; S.1.3: Based on the impenetrable boundary assumption, derive the aerodynamic coefficient matrix of the influence of attached vortices and wake vortices on the induced velocity of the control point. Establish the velocity equation at the control point: ; Then, solve for the attached vortex strength. .

[0061] S.1.4: Calculation of blade-induced aerodynamic lift based on extended theory and induced aerodynamic drag ; S.1.5: Calculate the airfoil lift coefficient based on the following formula. and the effective angle of attack of the airfoil : ; ; in, The effect of wind turbine pitch control on angle of attack.

[0062] S.1.6: Through effective angle of attack Find two-dimensional airfoil wind tunnel data to obtain the viscous aerodynamic lift coefficient. and aerodynamic drag coefficient Then, calculate the unsteady aerodynamic lift of the blades according to the following formula. Unsteady aerodynamic drag : ; ; in, air density, For the airfoil chord, , Based on effective angle of attack The lift and drag coefficients, including those containing viscous material, were obtained from a table. This is the length of the unit containing the airfoil.

[0063] S.1.7: Update the blade wake motion based on the fourth-order Runge-Kutta method.

[0064] S2: Based on the structural and mass parameters of the wind turbine blades, and using the nonlinear dynamic model of the long flexible blade, combined with the unsteady aerodynamic load calculated in S1, the nonlinear dynamic response of the blades is iteratively solved.

[0065] Specifically, such as Figure 4As shown, the nonlinear dynamic model of the blade can include: obtaining the blade structure and mass parameters, calculating the external loads on the blade (including gravity loads / inertial loads / aerodynamic loads), calculating the blade tangential stiffness matrix, mass matrix, and damping matrix, establishing nonlinear control equations, solving the blade response using nonlinear Newmark-β, then judging convergence based on the residual unbalanced force. If convergence is achieved, it is determined whether it is the final time. If it is not the final time, the time step is advanced, and the calculation of the external loads on the blade (including gravity loads / inertial loads / aerodynamic loads) is performed. If convergence is not achieved, the blade nodal positions are iteratively updated, co-rotation coordinate transformation is performed, and then the blade tangential stiffness matrix, mass matrix, and damping matrix are calculated.

[0066] Based on this, according to the structural and mass parameters of the wind turbine blades, and using the nonlinear dynamic model of long flexible blades, combined with the unsteady aerodynamic loads calculated by S1, the iterative solution of the nonlinear dynamic response of the blades can include the following steps: S.2.1: Obtain the blade structural parameters, and establish the tangential stiffness matrix of the blade structure by deriving the second-order transverse and longitudinal displacement fields and Green strain. : ; in, For the linear stiffness component, This refers to the portion with large deformation stiffness. This is the centrifugal tempering part.

[0067] S.2.2: Obtain blade mass parameters and derive the blade mass matrix. and structural damping matrix Establish the nonlinear governing equations for the blades to describe large structural deformations: ; Among them, external load It can be obtained by adding the calculated aerodynamic load to the blade's gravity load and inertial force load; S.2.3: Deriving the follower coordinate system using the co-rotation coordinate method The following co-rotation transformation relationship between the internal unit coordinate system and the global coordinate system of the blade is established to realize the description of the large rotation of the blade: ; S.2.4: Within the framework of the modified Lagrange method, time-step integration is performed using the nonlinear Newmark-β method, and the nonlinear dynamic response of the blade is solved iteratively at each time step using the Newton-Raphson method.

[0068] That is, by locally coupling the current nonlinear model of the blade, the analysis accuracy of the blade can be improved. The blade response will change the nodal position of the blade, thereby changing the aerodynamic calculation. The aerodynamic force will be input into the multibody dynamics model, thus indirectly affecting the overall analysis of the wind turbine.

[0069] S3: Based on the wave environment parameters of the target sea area, describe the nonlinear wave evolution in the outer domain of the wave field using a higher-order spectral method.

[0070] like Figure 5 As shown, HOS can include: solving the incident wave field in the outer domain using the pseudospectral method, then reconstructing the incident wave field in three dimensions, and then matching the boundary difference of the inner domain.

[0071] Based on this, and according to the wave environment parameters of the target sea area, describing the nonlinear wave evolution in the outer domain of the wave field using higher-order spectral methods can include the following steps: S.3.1: Solve for the nonlinear free surface boundary conditions to generate an incident wave field containing modulation instability. : ; ; in, It is the horizontal position vector; the first equation is the kinematic condition (describing the wavefront evolution), which has... It is the vertical velocity. The first equation is the convection term; the second equation is the dynamic condition (describing energy transfer), which has... It is a static pressure recovery item. It is a dynamic pressure term. It is a nonlinear coupling term.

[0072] S.3.2: For the incident wave field Perform three-dimensional reconstruction to obtain the horizontal velocity of the incident wave. and horizontal speed : ; ; in, This represents the two-dimensional inverse Fourier transform. For the horizontal wavenumber vector ( ), This indicates the calculation of the hyperbolic tangent. This represents a three-dimensional velocity potential spectrum.

[0073] S.3.3: The incident wave velocity field Interpolate to the inner domain boundary to account for the influence of the nonlinear evolution of the outer domain wave field on the nonlinear hydrodynamics of the inner domain.

[0074] S4: Based on the wave environment parameters of the target sea area, calculate the nonlinear hydrodynamics and platform motion response of the floating platform under wave-object interaction in the inner domain using the time-domain fully nonlinear potential flow theory and the higher-order boundary element method.

[0075] like Figure 5 As shown, the time-domain fully nonlinear hydrodynamic model can include: obtaining the floating platform's mass and shape parameters from the external platform network, then deriving the boundary integral frustum using Rankine sources, solving the integral frustum by discretization using higher-order boundary element methods, solving the total velocity potential by incident scattering separation, calculating the acceleration potential using virtual functions, calculating the platform's nonlinear hydrodynamics, then calculating the platform's total input load by using mooring / tower bottom loads and solving the coupled motion equations, determining whether it is the final time, if it is, the end, if not, then based on the time step, calculating the hybrid Eulerian-Lagrange update of the free surface mesh, and then switching to higher-order boundary element discretization to solve the integral equations.

[0076] Based on this, and according to the wave environment parameters of the target sea area, the calculation of the nonlinear hydrodynamics and platform motion response of the floating platform under wave-object interaction in the inner domain, based on the time-domain fully nonlinear potential flow theory and the higher-order boundary element method, can include the following steps: S.4.1: By using the Rankine source as the Green's function and deriving the following boundary integral equation using Green's second theorem, the boundary integral equation is discretized using the higher-order boundary element method: ; in, It is the velocity potential at point P. The self-influence of the velocity potential at point P. It is the Rankine Green's function. For the boundary velocity potential distribution, For boundary normal velocity perturbation, This represents the boundary tangential velocity perturbation.

[0077] S.4.2: Employing incident scattering separation technology Solve for the total velocity potential ; Among them, incident potential The scattering potential is obtained by directly reading the numerical solution calculated from the higher-order spectrum in S3. The instantaneous free surface is obtained by solving the boundary integral equation and updated using the hybrid Euler-Lagrange method. ,in, The velocity of the fluid unit. This represents the actual velocity of the fluid particles.

[0078] S.4.3: Calculated total velocity potential The acceleration potential can be indirectly calculated using the following formula. : ; in, This represents the normal acceleration caused by the platform's motion. This represents the interaction between the platform motion and the fluid velocity gradient. Indicates reference frame rotation correction, For the translational acceleration of the floating platform, The rotational speed of the floating platform. The rotational acceleration of the floating platform, Let be the position vector of the floating platform surface. Let be the unit normal vector of the floating platform; S.4.4: Acceleration potential based on indirect calculation Calculate the nonlinear wave hydrodynamic F of the floating platform wave : ; in, It is the pressure term of fluid kinetic energy conversion. It is the static pressure distribution caused by the gravity of the fluid.

[0079] S.4.5: Mooring Load Based on Mooring Model Calculation Platform The second-order viscous damping force of the platform is calculated using the viscous damping coefficient obtained from platform tank tests or CFD simulations. And through coordinate transformation, they are unified to the platform reference point; S.4.6: The total load on the platform is obtained by superimposing the nonlinear wave hydrodynamics, wind turbine tower base load, platform mooring load, and viscous damping load, and then inputting the coupled motion equations of the platform to solve for the rigid body motion response of the platform: ; S5: In calculating the overall dynamic response of the floating wind turbine at each moment, the motion and load responses calculated in the previous time step are used to update the input state of the floating wind turbine analysis and calculation in the current time step, so as to realize the bidirectional coupling and transmission of aerodynamic and hydrodynamic responses between the upper unit and the lower platform of the floating wind turbine.

[0080] Specifically, it can include: S.5.1: When calculating the total velocity at the blade vortex control point in step S.1.2, for the free inflow velocity... and rigid body motion velocity First, the blade position nodes are updated using the elastic deformation calculated by the blade nonlinear dynamics model at the previous moment (initial moment is 0) and the wind turbine rigid body motion calculated by the whole machine multibody dynamics model. Then, the free inflow wind speed and wind turbine rigid body motion speed in the environment are accurately converted to the blade nodes through the coordinate system, and the subsequent calculation of S1 is completed. S.5.2: When calculating the overall response of a floating wind turbine based on a multibody model, the previous moment (initial moment is 0) is first input, and the platform's rigid body acceleration, velocity, and displacement are calculated by the platform's coupled motion equations. Then, the motion response of each part of the overall structure, including the motion response of the floating platform, is simulated. S.5.3: When calculating the total input load of the floating platform in step S.4.6, the tower base load calculated by the floating wind turbine multibody model at the same time can be input first to calculate the influence of the whole machine load, including aerodynamic load, inertial load, gravity load and elastic force load.

[0081] Taking a 5MW semi-submersible floating wind turbine as an example, simulation analysis revealed that the current model has the same response trend as the mainstream wind turbine simulation model. At the same time, because the current model has better nonlinear analysis capabilities, it can more accurately capture the response differences caused by changes in operating conditions.

[0082] In the example above, the angular velocities and momentum of various parts of the floating wind turbine are derived based on multibody dynamics. By combining the overall coordinate transformation and motion / load transfer mechanisms, an integrated aerodynamic-hydraulic-multibody structure-elasticity-servo framework is established. Furthermore, considering the large deformation of the wind turbine's long, flexible blades and the complex operating environment in deep-sea areas, a free vortex wake-enhanced vortex grid aerodynamic model is coupled to analyze unsteady inflow and wake effects at sea. Further, a nonlinear aeroelastic model for the long, flexible blades with large structural deformation and rotation is considered, along with a time-domain fully nonlinear hydrodynamic model for the floating platform that can describe the influence of the outer wave field on the inner structure in normal / extreme environments and capture higher-order wave components. This example demonstrates how the scheme can consider the multibody dynamic coupling of the wind turbine itself and the strong nonlinear effects under external environmental influences. While meeting engineering computational efficiency requirements, it achieves higher accuracy in simulating the operating state of the floating wind turbine, playing a crucial role in the reliable design and safe operation of large floating wind turbines in deep-sea areas.

[0083] This example presents a highly nonlinear simulation method for floating wind turbines suitable for complex wind and wave environments in deep seas, which may include the following steps: Step 1: Obtain the model parameters such as shape and mass of the target floating wind turbine. Based on the multibody dynamics method, divide the floating wind turbine into multiple body structures such as blades, rotor, nacelle, main shaft, yaw bearing, tower, and floating platform. Construct a multibody model with 31 degrees of freedom and establish the load and motion transmission path of the whole machine. Step 2: Based on the relative positional relationship of each structure of the floating wind turbine, establish the local coordinate system of each structure, and take the origin of the tower bottom as the reference origin of the overall coordinate system to establish the coordinate transformation relationship of all structures of the whole machine from the local to the overall coordinate system; Step 3: Obtain the hydrological and meteorological conditions of the target operating area (e.g., wind conditions, sea conditions, and other environmental parameters), and construct the input environmental parameters for each load model; Step 4: Based on the blade free vortex wake-enhanced vortex grid aerodynamic model and input wind conditions, calculate the unsteady aerodynamic loads of the three blades of the wind turbine, and then superimpose them on the wind turbine coordinate system; then, transform the wind turbine aerodynamic loads onto each structure in turn as the aerodynamic load inputs for each structure. Step 5: Based on the time-domain potential flow fully nonlinear hydrodynamic model of the floating platform and the input wave parameters, calculate the nonlinear hydrodynamics of the floating platform; Step 6: Obtain the structural parameters of the wind turbine blades, construct the nonlinear control equations of the blades based on the nonlinear dynamic model of the long flexible blades, and combine the unsteady aerodynamic loads calculated in Step 4 with the gravity and inertial loads of the blades to iteratively solve the nonlinear dynamic response of the blades. Step 7: Through coordinate transformation, transfer the nonlinear dynamic response of the blade to the global coordinate system and input it into the multibody dynamic model of the whole machine. Calculate the generalized active force and generalized inertial force of each body structure of the wind turbine, and solve the motion response of each body structure simultaneously. Step 8: By superimposing the wind turbine tower base load, nonlinear hydrodynamic load, mooring load, and viscous damping load onto the floating platform reference point, the total external load of the floating platform is obtained, and the coupled motion equation of the floating platform is input to calculate the higher-order hydrodynamic motion response of the platform. Throughout the above process, the effects of the wind turbine's rigid body motion and blade elastic deformation on the aerodynamic load in step 4 were considered. Furthermore, steps 7 and 8 considered the coupled transfer of load and motion response within the time step. Specifically, considering the coupled transfer of load and motion response within the time step could involve using the previous time step... The calculated platform velocity and acceleration (initially 0) are then transformed to the origin at the bottom of the tower and incorporated into the current time step. The multibody dynamics equations are used to calculate the motion response of each body structure of the wind turbine under the motion of the floating platform; then, the current time step is... The total load at the base of the tower, calculated considering aerodynamic loads, inertial loads, gravity loads, and damping loads, is transformed to the platform reference point. The wave hydrodynamic forces and other loads (e.g., viscous damping forces and mooring loads) obtained from the joint calculation are then input into the platform's coupled motion equations to calculate the floating platform's motion response. This process is repeated to achieve bidirectional coupling.

[0084] Specifically, the simulation method of the blade free vortex wake-enhanced vortex grid aerodynamic model in step 4 above can include: Step 4-1: Consider the evolution and mutual influence of the blade attached vortex (at the control point of the lifting surface vortex grid) and the wake vortex (detached from the trailing edge of the blade), and calculate the induced velocity of the vortex on the blade control point during this process based on the Biot-Savart theorem. ; Step 4-2: Transform the free inflow velocity and the rigid body motion velocity of the floating fan in the global coordinate system to the blade coordinate system, and combine the free inflow velocity... Wind turbine rigid body motion velocity and blade elastic deformation rate Obtain the total speed at the control point ; Step 4-3: Based on the impenetrable boundary assumption, derive the aerodynamic coefficient matrix of the influence of attached vortices and wake vortices on the induced velocity of the control point. Establish the velocity equation at the control point. Solve for the strength of attached vortices ; Step 4-4: Calculate the unsteady aerodynamic lift of the blades based on Joukowski extended theory and lookup table method (based on two-dimensional airfoil wind tunnel data). Unsteady aerodynamic drag : ; ; in, It is air density. It is the airfoil chord length, , Based on effective angle of attack The lift and drag coefficients, including those containing viscous material, were obtained from a table. The length of the unit containing the airfoil. Due to the strength of the attached vortex The unsteady induced drag calculated using the Joukowski extended theory.

[0085] Steps 4-5: Update the blade wake motion based on the 4th-order Runge-Kutta method.

[0086] In step 4-4 above, by introducing a hybrid calculation method to derive the effective angle of attack, the iterative process of the attached vortex strength is optimized, significantly improving the computational efficiency of aerodynamic forces. Specifically, it can be based on the attached vortex strength... And the Joukowski extended theory directly solves for the unsteady induced lift of the blades. The airfoil lift coefficient is calculated using the airfoil aerodynamic lift formula. Then calculate the effective angle of attack of the airfoil. : ; ; in, The effect of wind turbine pitch control on angle of attack.

[0087] Through effective angle of attack By searching two-dimensional airfoil wind tunnel data, the viscous aerodynamic lift coefficient can be obtained. and aerodynamic drag coefficient Then substitute the values ​​into step 4-4 to complete the subsequent aerodynamic calculations.

[0088] In step 6 above, the nonlinear dynamic model of the long flexible blade is established based on the second-order Euler-Bernoulli beam and the co-rotation coordinate method, which may include: Step 6-1: Obtain the blade structural parameters. By deriving the second-order transverse and longitudinal displacement fields and Green strain, establish the tangential stiffness matrix of the blade structure. : ; in, For the linear stiffness component, This refers to the portion with large deformation stiffness. This is the centrifugal tempering part.

[0089] Step 6-2: Obtain blade mass parameters and derive the blade mass matrix. and structural damping matrix Establish nonlinear governing equations for blades that can describe large structural deformations. Among them, external load It can be obtained by adding the aerodynamic load calculated above to the gravity load and inertial force load of the blade; Step 6-3: Derive the follower coordinate system using the co-rotation coordinate method Establish the co-rotation transformation relationship between the internal unit coordinate system and the global coordinate system of the blade. This enables the description of large blade rotation. Step 6-4: Within the framework of the modified Lagrange method, time-step integration is performed using the nonlinear Newmark-β method, and the nonlinear dynamic response of the blade is solved iteratively using the Newton-Raphson method at each time step. Furthermore, the blade nodal position can be updated by calculating the nonlinear elastic deformation of the blade, thus considering the aeroelastic effect during the transition of the free-flowing wind and the rigid body motion velocity of the wind turbine to the blade coordinate system. This allows for the calculation of unsteady aerodynamic loads considering the aeroelastic effect in subsequent steps. In implementation, the calculated unsteady aerodynamic loads incorporating the aeroelastic effect can be used as the aerodynamic component of the external load in step 6-2, thereby enabling the analysis of the blade's nonlinear aeroelastic motion response under the dual effects of internal blade geometric nonlinearity and deformation-induced changes in external loads.

[0090] The first part of the simulation method for the fully nonlinear hydrodynamic model of the floating platform in step 5 above is based on the high-order spectral method to describe the nonlinear wave evolution in the outer domain of the wave field, which may specifically include: Step 5-1-1: Solve the nonlinear free surface boundary conditions using the pseudospectral method to generate an incident wave field containing modulation instability. : ; ; in, Given the horizontal position vector, the first equation is the kinematic condition (used to describe the wavefront evolution). Vertical velocity, The first equation is the convection term, and the second equation is the dynamic condition (used to describe energy transfer). This is a static pressure recovery item. For dynamic pressure, This is a nonlinear coupling term.

[0091] Step 5-1-2: For the incident wave field Perform three-dimensional reconstruction to obtain the horizontal velocity of the incident wave. and horizontal speed : ; in, This represents the two-dimensional inverse Fourier transform. The horizontal wavenumber vector, , This indicates the calculation of the hyperbolic tangent. It is a three-dimensional velocity potential spectrum.

[0092] Step 5-1-3: The incident wave velocity field Interpolate to the inner domain boundary to account for the influence of the nonlinear evolution of the outer domain wave field on the nonlinear hydrodynamics of the inner domain.

[0093] The second part of the simulation method for the time-domain potential flow fully nonlinear hydrodynamic model of the floating platform in step 5 above is based on the time-domain fully nonlinear potential flow theory and the higher-order boundary element method to calculate the nonlinear hydrodynamics of the floating platform under the wave-object interaction in the inner domain. Specifically, it may include: Step 5-2-1: Using Rankine sources as Green's functions, derive the boundary integral equations using Green's second theorem. The boundary integral equation is discretized using the higher-order boundary element method.

[0094] in, Let P be the velocity potential at the field point. The self-influence of the velocity potential at point P. For the Rankine Green's function, For the boundary velocity potential distribution, For boundary normal velocity perturbation, This represents the boundary tangential velocity perturbation.

[0095] Step 5-2-2: Employing incident scattering separation technology Solve for the total velocity potential Among them, incident potential The scattering potential can be obtained by directly reading the numerical solution calculated from the higher-order spectrum. The instantaneous free surface can be solved by boundary integral equations and updated using the hybrid Euler-Lagrange method. We obtained, among which, The velocity of the fluid unit. This represents the actual velocity of the fluid particles.

[0096] Step 5-2-3: Based on the calculated total velocity potential The acceleration potential is indirectly calculated using the virtual function method. : ; in, The normal acceleration caused by the platform's motion. The interaction between platform motion and fluid velocity gradient, For reference frame rotation correction, For the translational acceleration of the floating platform, The rotational speed of the floating platform. The rotational acceleration of the floating platform, Let be the position vector of the floating platform surface. Let be the unit normal vector of the floating platform; Step 5-2-4: Acceleration potential based on indirect calculation Calculate the nonlinear wave hydrodynamics Fwave of the floating platform: ; in, The pressure term represents the conversion of fluid kinetic energy. This refers to the static pressure distribution caused by fluid gravity.

[0097] In the example above, the unsteady aerodynamic model of the blade is derived based on the free vortex wake-enhanced vortex lattice method. Specifically, based on cutting-edge theories (e.g., nonlinear vortex lattice method), the calculation method for the effective angle of attack is derived, and the vortex intensity iteration process is optimized. This retains the unsteady aerodynamic analysis capability of the original method and significantly improves the calculation speed. The established unsteady aerodynamic model of the blade can effectively describe the evolution and interaction of attached vortices and wake vortices during blade motion, thereby accurately analyzing the influence of vortex elements on the blade surface flow field (e.g., near-wake flow field) and calculating vortex-induced velocities. At the same time, a lookup table method (e.g., wind tunnel aerodynamic data of two-dimensional airfoils) is used to introduce viscous aerodynamic drag correction, enabling high-precision aerodynamic characteristic analysis of floating wind turbines in deep-sea environments (which may lead to complex conditions such as large yaw and high thrust).

[0098] Furthermore, by incorporating the effects of blade rigid body motion and elastic deformation on blade position and attitude into the free-flowing wind (aeroelastic coupling), and inputting both the blade rigid body motion velocity and elastic deformation velocity into the unsteady aerodynamic model of the blade, the influence of aeroelastic effects on the aerodynamic performance of the wind turbine is fully considered, realistically simulating the aerodynamic loads during the movement of the floating wind turbine. By applying the influence of nonlinear blade deformation to the free-flowing wind and changing the aerodynamic loads, the effects of aeroelastic coupling can be considered simultaneously on the nonlinear deformation analysis of the blade dynamics model. That is, under the dual effects of internal geometric nonlinearity of the blade and changes in external loads caused by deformation, the blade deformation during the movement of the floating wind turbine can be accurately analyzed.

[0099] Furthermore, the hydrodynamic model of the floating platform established in this example derives its wave-object interaction analysis in the inner wave field based on time-domain fully nonlinear potential flow theory and higher-order boundary element method. It avoids the approximation process of indirectly converting from frequency-domain potential flow method (currently widely used) to time-domain processes, enabling higher-precision analysis of the higher-order hydrodynamic loads and motion responses of the floating platform. This effectively handles transient and strongly nonlinear hydrodynamic problems, achieving accurate hydrodynamic analysis of floating wind turbines under complex sea conditions. The outer wave field analysis of the floating platform hydrodynamic model established in this example is based on higher-order spectral methods, effectively simulating the nonlinear evolution of waves and the interactions between waves with high computational efficiency (computational complexity of O(NlogN)). By introducing the incident potential into the inner domain, the influence of nonlinear wave evolution on the hydrodynamics of the floating platform can be considered, enabling hydrodynamic performance analysis of floating wind turbines under extreme sea conditions. Platform modeling and mesh generation are achieved using external 3D software, and the wave surface parameter file of the target platform is generated using an internal program, enabling nonlinear hydrodynamic analysis of floating platforms of any form.

[0100] Furthermore, the multibody dynamics model of the floating wind turbine established in this example can realize the bidirectional coupling and transmission of the aerodynamic and hydrodynamic responses of the floating wind turbine between the upper unit and the lower platform. It accurately calculates the generalized inertial force under multibody coupling by measuring the motion velocity and acceleration of each structural element, effectively analyzing the strong nonlinear effects of the floating wind turbine's own multibody dynamic coupling and the combined effects of the external environment, and accurately assessing the operating status of the floating wind turbine in complex deep-sea environments. Through the aforementioned multibody dynamics model of the floating wind turbine, the evolution of the mid- and far-field wake of the floating wind turbine can be analyzed by fully considering the rigid body motion of the entire turbine (including the motion of the floating platform) and the aeroelastic coupling effect. Existing wake analyses based on CFD methods struggle to capture this overall aeroelastic effect.

[0101] The methods and embodiments provided in the above-described embodiments of this application can be executed in a mobile terminal, computer terminal, or similar computing device. Taking operation on an electronic device as an example... Figure 6 This is a hardware structure block diagram of an electronic device suitable for a highly nonlinear simulation method of large floating wind turbines, as provided in this application. Figure 6 As shown, the electronic device 10 may include one or more (only one is shown in the figure) processors 02 (processors 02 may include, but are not limited to, processing devices such as microprocessors (MCUs) or programmable logic devices (FPGAs), a memory 04 for storing data, and a transmission module 06 for communication functions. Those skilled in the art will understand that... Figure 6 The structure shown is for illustrative purposes only and does not limit the structure of the electronic device described above. For example, electronic device 10 may also include... Figure 6 The more or fewer components shown, or having the same Figure 6 The different configurations shown.

[0102] The memory 04 can be used to store software programs and modules for application software, such as the program instructions / modules corresponding to the strongly nonlinear simulation method for large floating wind turbines in this embodiment of the application. The processor 02 executes various functional applications and data processing by running the software programs and modules stored in the memory 04, thereby realizing the above-mentioned application of an integrated modeling and analysis method for floating wind turbines applicable to deep-sea areas. The memory 04 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 04 may further include memory remotely located relative to the processor 02, and these remote memories can be connected to the electronic device 10 via a network. Examples of the above-mentioned networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0103] The transmission module 06 is used to receive or send data via a network. Specific examples of the network described above may include a wireless network provided by the communication provider of the electronic device 10. In one example, the transmission module 06 includes a Network Interface Controller (NIC), which can connect to other network devices via a base station to communicate with the Internet. In another example, the transmission module 06 may be a Radio Frequency (RF) module, used for wireless communication with the Internet.

[0104] At the software level, the aforementioned simulation device for highly nonlinear large-scale floating wind turbines can be used as follows: Figure 7 As shown, it includes: The acquisition module 701 is used to acquire model parameters of the target floating wind turbine, wherein the model parameters include at least one of the following: shape parameters and mass parameters; The construction module 702 is used to divide the target floating wind turbine into multiple body structures according to the model parameters, so as to construct a multibody model containing multiple degrees of freedom and establish the whole machine load and motion transmission path. The multiple body structures include at least one of the following: blades, wind turbine, nacelle, main shaft, yaw bearing, tower, and floating platform. Module 703 is used to establish local coordinate systems for each structure based on the relative positional relationship of each structure in the target floating wind turbine, and to establish coordinate transformation relationships from local to global coordinate systems for all structures of the whole machine, with the tower bottom origin as the reference origin of the global coordinate system. The first calculation module 704 is used to calculate the aerodynamic load input of each body structure and to calculate the nonlinear dynamic response of the blade based on the aerodynamic load input of each body structure. The second calculation module 705 is used to transform the nonlinear dynamic response of the blade to the global coordinate system through the coordinate transformation relationship and input it into the multibody dynamic model of the whole machine. It calculates the generalized active force and generalized inertial force of each body structure in the target floating wind turbine, and solves them simultaneously to obtain the motion response of each body structure of the target floating wind turbine.

[0105] In one embodiment, the first calculation module 704 can specifically acquire wind condition parameters of the target floating wind turbine operating area; establish a free vortex wake enhanced vortex grid aerodynamic model of the blades; calculate the unsteady aerodynamic loads of the three blades of the wind turbine based on the free vortex wake enhanced vortex grid aerodynamic model of the blades and the wind condition parameters; transform the coordinates of the unsteady aerodynamic loads of the three blades to the wind turbine coordinate system and superimpose them to obtain the aerodynamic loads of the wind turbine; and transform the coordinates of the aerodynamic loads of the wind turbine to each body structure in sequence as the aerodynamic load input of each body structure.

[0106] In one embodiment, the first calculation module 704 can specifically obtain the structural parameters of the blade; construct the nonlinear control equation of the blade based on the nonlinear dynamic model of the long flexible blade and the structural parameters of the blade; and iteratively solve the nonlinear dynamic response of the blade based on the nonlinear control equation, combined with the unsteady aerodynamic load of the blade and the gravity and inertial force load of the blade.

[0107] In one implementation, establishing a free vortex wake-enhanced vortex lattice aerodynamic model for the blades may include: Based on the evolution and interaction of the blade attached vortex and wake vortex, the induced velocity generated by the vortex at the blade control point is calculated. ; The free-flowing air and the rigid body velocity of the target floating wind turbine in the global coordinate system are transformed to the blade coordinate system, and the free-flowing air velocity is used as the basis for this transformation. Wind turbine rigid body motion velocity and blade elastic deformation rate The total velocity at the control point is obtained: ; in, The total speed at the control point, For free-flow wind speed, The velocity of the rigid body of the wind turbine. The elastic deformation rate of the blade, For induced velocity, i represents the i-th control point of the vortex lattice on the blade lifting surface; Based on the impenetrable boundary assumption, the aerodynamic coefficient matrix of the influence of attached vortex and wake vortex on the induced velocity of the control point is determined. Based on the aerodynamic coefficient matrix, establish the velocity equation at the control point, and calculate the attached vortex intensity based on the velocity equation. ; Calculate the unsteady aerodynamic lift and unsteady aerodynamic drag of the blades using the following formulas: ; ; in, For unsteady aerodynamic lift of the blades, For unsteady aerodynamic drag of the blades, air density, For the airfoil chord, The aerodynamic lift coefficient includes viscosity. For the effective angle of attack of the airfoil, The aerodynamic drag coefficient includes viscosity. The length of the unit containing the airfoil. Based on the strength of the attached vortex The calculated unsteady induced drag is given by j, which represents the j-th wake vortex that detaches from the trailing edge of the blade.

[0108] In one embodiment, obtaining the viscous aerodynamic lift coefficient and the viscous aerodynamic drag coefficient may include: Calculate the effective angle of attack of the airfoil using the following formula: ; ; in, For the effective angle of attack of the airfoil, It is the effect of wind turbine pitch control on angle of attack. For unsteady induced lift of the blades, The lift coefficient of the airfoil; By matching the effective angle of attack of the airfoil with the two-dimensional airfoil wind tunnel data through a lookup table, the viscous aerodynamic lift coefficient and the viscous aerodynamic drag coefficient are obtained.

[0109] In one embodiment, the nonlinear dynamic response of the blade is obtained iteratively by combining the nonlinear control equations with the unsteady aerodynamic loads on the blade and the gravity and inertial force loads on the blade. This may include: Based on the blade's structural parameters, the tangential stiffness matrix of the blade structure is established by deriving the second-order transverse and longitudinal displacement fields and Green strain. : ; in, Here is the tangent stiffness matrix. For the linear stiffness component, This refers to the portion with large deformation stiffness. This is the centrifugal tempering part; Obtain the mass parameters of the blade, and determine the mass matrix and structural damping matrix of the blade based on the mass parameters; The external load is obtained by adding the aerodynamic load to the blade's gravity load and inertial force load. Based on the external load, tangent stiffness matrix, mass matrix, and structural damping matrix, the nonlinear governing equations for the blades describing large structural deformations are established: ; in, This represents the blade displacement acceleration. Indicates the blade displacement velocity. This represents the increment of blade displacement. For external loads, Here is the tangent stiffness matrix. For the quality matrix, Here is the structural damping matrix; The servo coordinate system is derived using the co-rotation coordinate method; Based on the servo coordinate system, establish the co-rotation transformation relationship between the internal element coordinate system and the global coordinate system of the blade to realize the description of the large rotation of the blade: ; in, This represents the moving coordinate system, which is the coordinate transformation matrix from the unit coordinate system to the global coordinate system. This represents the tangent stiffness matrix of the blade element; Within the framework of the modified Lagrange method, time-step integration is performed using the nonlinear Newmark-β method, and the nonlinear dynamic response of the blade is solved iteratively at each time step using the Newton-Raphson method.

[0110] In one embodiment, after calculating the aerodynamic load inputs for each structural element, the method may further include: Obtain wave parameters; Based on the higher-order spectral model and the wave parameters, the irregular incident waves acting on the floating platform are calculated. The nonlinear wave hydrodynamics of the floating platform under the wave-object interaction in the inner domain is calculated based on the time-domain fully nonlinear potential flow theory and the higher-order boundary element method.

[0111] In one implementation, calculating the irregular incident waves acting on the floating platform based on a higher-order spectral model and the wave parameters may include: The nonlinear free-surface boundary conditions are solved using the pseudospectral method to generate an incident wave field containing modulation instability: ; ; in, Vertical velocity, For convection terms, This is the static pressure recovery item. For dynamic pressure, It is a nonlinear coupling term. For the incident wave field; The incident wave field is reconstructed in three dimensions to obtain the horizontal velocity of the incident wave. and horizontal speed , ; ; in, The horizontal velocity of the incident wave, It is a horizontal position vector. For horizontal velocity, This is a two-dimensional inverse Fourier transform. The horizontal wavenumber vector, , To calculate the hyperbolic tangent, It is a three-dimensional velocity potential spectrum. For the incident wave velocity field; The incident wave velocity field is interpolated to the inner domain boundary to determine the influence of the nonlinear evolution of the outer domain wave field on the nonlinear hydrodynamics of the inner domain.

[0112] In one implementation, calculating the nonlinear wave hydrodynamics of the floating platform under the wave-object interaction in the inner domain based on the time-domain fully nonlinear potential flow theory and the higher-order boundary element method may include: Establish the boundary integral equation: ; in, Let P be the velocity potential at the field point. The self-influence of the velocity potential at point P. For the Rankine Green's function, For the boundary velocity potential distribution, For boundary normal velocity perturbation, For boundary tangential velocity perturbation, Indicates the fixed angle factor. Indicates the field point. Represents velocity potential, Indicates the source point, Represents the Green's function. Represents the normal derivative along the boundary. Indicates the integral boundary where the source point is located; Discretize the boundary integral equation using the higher-order boundary element method; The scattering potential is calculated using the boundary integral equation. ; Through scattering potential Calculate the total velocity potential ; Through total velocity potential The acceleration potential is calculated. : ; in, For acceleration potential, The total velocity potential, This refers to the normal acceleration caused by the motion of the floating platform. This refers to the interaction between the motion of the floating platform and the fluid velocity gradient. For reference frame rotation correction, This represents the actual velocity of the fluid particles. For the translational acceleration of the floating platform, The rotational speed of the floating platform. The rotational acceleration of the floating platform, Let be the position vector of the floating platform surface. Let be the unit normal vector of the floating platform; According to the acceleration potential Calculate the nonlinear wave hydrodynamics of the floating platform. : ; in, This represents the nonlinear wave hydrodynamics of a floating platform. air density, The unit normal vector representing the boundary of the integral. Indicates the integral boundary where the field point is located. This refers to the static pressure distribution caused by fluid gravity. The pressure term represents the conversion of fluid kinetic energy.

[0113] In one embodiment, after calculating the nonlinear wave hydrodynamics of the floating platform under the wave-object interaction in the inner domain based on the time-domain fully nonlinear potential flow theory and the higher-order boundary element method, the method may further include: Obtain the velocity and acceleration of the floating platform at the previous time step; The motion velocity and acceleration of the floating platform in the previous time step are transformed to the origin at the bottom of the tower through coordinate transformation, so as to calculate the motion response of each body structure of the target floating wind turbine under the motion of the floating platform according to the multibody dynamics equations of the current time step. The total load at the bottom of the tower, calculated at the current time step considering aerodynamic loads, inertial loads, gravity loads, and damping loads, is transformed to the platform reference point. The nonlinear wave hydrodynamics, viscous damping force, and mooring load of the floating platform are input into the platform's coupled motion equations to calculate the floating platform's motion response.

[0114] The embodiments of this application also provide a specific implementation of an electronic device capable of implementing all steps in the strongly nonlinear simulation method for large floating wind turbines described in the above embodiments. The electronic device specifically includes: a processor, a memory, a communication interface, and a bus; wherein the processor, memory, and communication interface communicate with each other via the bus; the processor is used to call a computer program in the memory, and when the processor executes the computer program, it implements all steps in the strongly nonlinear simulation method for large floating wind turbines described in the above embodiments. For example, when the processor executes the computer program, it implements the following steps: Step 1: Obtain the model parameters of the target floating wind turbine, wherein the model parameters include at least one of the following: shape parameters and mass parameters; Step 2: Divide the target floating wind turbine into multiple body structures according to the model parameters to construct a multibody model with multiple degrees of freedom, and establish the overall load and motion transmission path. The multiple body structures include at least one of the following: blades, rotor, nacelle, main shaft, yaw bearing, tower, and floating platform. Step 3: Based on the relative positional relationship of each structure in the target floating wind turbine, establish the local coordinate system of each structure, and take the origin of the tower bottom as the reference origin of the overall coordinate system to establish the coordinate transformation relationship of all structures of the whole machine from the local to the overall coordinate system. Step 4: Calculate the aerodynamic load input for each body structure, and calculate the nonlinear dynamic response of the blade based on the aerodynamic load input for each body structure; Step 5: Through the coordinate transformation relationship, the nonlinear dynamic response of the blade is transformed into the global coordinate system and input into the multibody dynamic model of the whole machine. The generalized active force and generalized inertial force of each body structure in the target floating wind turbine are calculated, and the motion response at each body structure of the target floating wind turbine is obtained by solving the equations simultaneously.

[0115] Embodiments of this application also provide a computer-readable storage medium capable of implementing all steps of the strongly nonlinear simulation method for large floating wind turbines described in the above embodiments. The computer-readable storage medium stores a computer program that, when executed by a processor, implements all steps of the strongly nonlinear simulation method for large floating wind turbines described in the above embodiments. For example, when the processor executes the computer program, it implements the following steps: Step 1: Obtain the model parameters of the target floating wind turbine, wherein the model parameters include at least one of the following: shape parameters and mass parameters; Step 2: Divide the target floating wind turbine into multiple body structures according to the model parameters to construct a multibody model with multiple degrees of freedom, and establish the overall load and motion transmission path. The multiple body structures include at least one of the following: blades, rotor, nacelle, main shaft, yaw bearing, tower, and floating platform. Step 3: Based on the relative positional relationship of each structure in the target floating wind turbine, establish the local coordinate system of each structure, and take the origin of the tower bottom as the reference origin of the overall coordinate system to establish the coordinate transformation relationship of all structures of the whole machine from the local to the overall coordinate system. Step 4: Calculate the aerodynamic load input for each body structure, and calculate the nonlinear dynamic response of the blade based on the aerodynamic load input for each body structure; Step 5: Through the coordinate transformation relationship, the nonlinear dynamic response of the blade is transformed into the global coordinate system and input into the multibody dynamic model of the whole machine. The generalized active force and generalized inertial force of each body structure in the target floating wind turbine are calculated, and the motion response at each body structure of the target floating wind turbine is obtained by solving the equations simultaneously.

[0116] As described above, this embodiment divides the target floating wind turbine into multiple body structures based on the model parameters of the target floating wind turbine to construct a multibody model with multiple degrees of freedom, and establishes the overall load and motion transmission path; based on the relative positional relationship of each body structure in the target floating wind turbine, a local coordinate system is established for each body structure, and the origin of the tower base is used as the reference origin of the global coordinate system to establish the coordinate transformation relationship of all body structures from the local to the global coordinate system; the aerodynamic load input of each body structure is calculated, and the nonlinear dynamic response of the blades is calculated based on the aerodynamic load input of each body structure; through the coordinate transformation relationship, the nonlinear dynamic response of the blades is transformed to the global coordinate system and input into the multibody dynamic model of the whole machine, and the generalized active force and generalized inertial force of each body structure in the target floating wind turbine are calculated, so as to solve simultaneously to obtain the motion response at each body structure of the target floating wind turbine. The multibody dynamics model of the floating wind turbine established in this example can realize the bidirectional coupling and transmission of the aerodynamic and hydrodynamic responses of the floating wind turbine between the upper unit and the lower platform. By accurately calculating the generalized inertial force under multibody coupling through the motion velocity and acceleration of each body structure, it can effectively analyze the strong nonlinear effects under the combined action of the multibody dynamic coupling of the floating wind turbine itself and the external environment. Thus, it can accurately determine the motion response of each body structure of the target floating wind turbine, so as to accurately assess the operating status of the floating wind turbine in the complex environment of the deep sea.

[0117] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. In particular, hardware + program embodiments are relatively simple in description because they are fundamentally similar to method embodiments; relevant parts can be referred to the descriptions in the method embodiments.

[0118] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0119] While this application provides the method operation steps as described in the embodiments or flowcharts, more or fewer operation steps may be included based on conventional or non-inventive labor. The order of steps listed in the embodiments is merely one possible execution order among many and does not represent the only execution order. In actual device or client product execution, the methods shown in the embodiments or drawings can be executed sequentially or in parallel (e.g., in a parallel processor or multi-threaded processing environment).

[0120] While this specification provides method operation steps as described in the embodiments or flowcharts, more or fewer operation steps may be included based on conventional or non-inventive means. The order of steps listed in the embodiments is merely one possible execution order among many and does not represent the only execution order. In actual device or end product execution, the methods shown in the embodiments or drawings may be executed sequentially or in parallel (e.g., in a parallel processor or multi-threaded processing environment, or even a distributed data processing environment). The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, product, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, product, or apparatus. Without further limitations, the presence of other identical or equivalent elements in the process, method, product, or apparatus that includes said elements is not excluded.

[0121] For ease of description, the above devices are described in terms of function, divided into various modules. Of course, in implementing the embodiments of this specification, the functions of each module can be implemented in one or more software and / or hardware components, or a module that performs the same function can be implemented by a combination of multiple sub-modules or sub-units. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between devices or units, and may be electrical, mechanical, or other forms.

[0122] Those skilled in the art will also know that, besides implementing the controller using purely computer-readable program code, the same functions can be achieved by logically programming the method steps, making the controller function as logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers (PLCs), and embedded microcontrollers. Therefore, such a controller can be considered a hardware component, and the devices within it used to implement various functions can also be considered structures within that hardware component. Alternatively, the devices used to implement various functions can be considered as both software modules implementing the method and structures within a hardware component.

[0123] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0124] Those skilled in the art will understand that the embodiments of this specification can be provided as methods, systems, or computer program products. Therefore, the embodiments of this specification can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, the embodiments of this specification can take the form of computer program products 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 code.

[0125] The embodiments described in this specification can be described in the general context of computer-executable instructions, such as program modules, that are executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. The embodiments of this specification can also be practiced in distributed computing environments where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0126] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, system embodiments are basically similar to method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. In the description of this specification, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments in this specification. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0127] The above description is merely an embodiment of the present specification and is not intended to limit the embodiments of the present specification. For those skilled in the art, various modifications and variations can be made to the embodiments of the present specification. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the embodiments of the present specification should be included within the scope of the claims of the embodiments of the present specification.

Claims

1. A simulation method for highly nonlinear large-scale floating wind turbines, characterized in that, The method includes: Obtain the model parameters of the target floating wind turbine, wherein the model parameters include at least one of the following: shape parameters and mass parameters; The target floating wind turbine is divided into multiple body structures according to the model parameters to construct a multibody model with multiple degrees of freedom, and to establish the overall load and motion transmission path. The multiple body structures include at least one of the following: blades, rotor, nacelle, main shaft, yaw bearing, tower, and floating platform. Based on the relative positional relationship of each structure in the target floating wind turbine, a local coordinate system is established for each structure, and the origin of the tower bottom is taken as the reference origin of the overall coordinate system. The coordinate transformation relationship of all structures of the whole machine from the local to the overall coordinate system is established. Calculate the aerodynamic load input for each body structure, and calculate the nonlinear dynamic response of the blade based on the aerodynamic load input for each body structure; Through the coordinate transformation relationship, the nonlinear dynamic response of the blade is transformed into the global coordinate system and input into the multibody dynamic model of the whole machine. The generalized active force and generalized inertial force of each body structure in the target floating wind turbine are calculated, and the motion response at each body structure of the target floating wind turbine is obtained by solving them simultaneously. The calculation of aerodynamic load inputs for each structure includes: acquiring wind condition parameters for the operating area of ​​the target floating wind turbine; establishing a free vortex wake enhanced vortex grid aerodynamic model for the blades; calculating the unsteady aerodynamic loads of the three blades of the wind turbine based on the free vortex wake enhanced vortex grid aerodynamic model and the wind condition parameters; transforming the coordinates of the unsteady aerodynamic loads of the three blades to the wind turbine coordinate system and superimposing them to obtain the aerodynamic loads of the wind turbine; and sequentially transforming the coordinates of the aerodynamic loads of the wind turbine to each structure as the aerodynamic load inputs for each structure. The establishment of the free vortex wake-enhanced vortex lattice aerodynamic model for the blades includes: Based on the evolution and mutual influence of the blade attachment vortex and wake vortex, the induced velocity generated by the vortex at the blade control point is calculated. The free-flowing air velocity and the rigid body motion velocity of the target floating wind turbine in the global coordinate system are transformed to the blade coordinate system, and the total velocity at the control point is obtained by using the free-flowing air velocity, the rigid body motion velocity of the wind turbine, and the elastic deformation velocity of the blades. ； in, The total speed at the control point, For free-flow wind speed, The velocity of the rigid body of the wind turbine. The elastic deformation rate of the blade, For induced velocity, i represents the i-th control point of the vortex lattice on the blade lifting surface; Based on the impenetrable boundary assumption, the aerodynamic coefficient matrix of the influence of attached vortex and wake vortex on the induced velocity of the control point is determined. Based on the aerodynamic coefficient matrix, establish the velocity equation at the control point, and calculate the attached vortex intensity based on the velocity equation. ; Calculate the unsteady aerodynamic lift and unsteady aerodynamic drag of the blades using the following formulas: ； ； in, For unsteady aerodynamic lift of the blades, For unsteady aerodynamic drag of the blades, air density, For the airfoil chord, Based on effective angle of attack The obtained viscous aerodynamic lift coefficient, For the effective angle of attack of the airfoil, Based on effective angle of attack The obtained aerodynamic drag coefficient with viscosity was found. The length of the unit containing the airfoil. Based on the strength of the attached vortex The calculated unsteady induced drag is given by j, which represents the j-th wake vortex that detaches from the trailing edge of the blade.

2. The method according to claim 1, characterized in that, The nonlinear dynamic response of the blades is calculated based on the aerodynamic load inputs of each structural element, including: Obtain the structural parameters of the blade; Based on the nonlinear dynamic model of the long flexible blade and the structural parameters of the blade, the nonlinear control equations of the blade are constructed. Based on the aforementioned nonlinear control equations, and combined with the unsteady aerodynamic loads on the blades as well as the gravity and inertial loads on the blades, the nonlinear dynamic response of the blades is obtained by iterative solution.

3. The method according to claim 1, characterized in that, Obtaining the viscous aerodynamic lift coefficient and the viscous aerodynamic drag coefficient includes: Calculate the effective angle of attack of the airfoil using the following formula: ； ； in, For the effective angle of attack of the airfoil, It is the effect of wind turbine pitch control on angle of attack. For unsteady induced lift of the blades, The lift coefficient of the airfoil; By matching the effective angle of attack of the airfoil with the two-dimensional airfoil wind tunnel data through a lookup table, the viscous aerodynamic lift coefficient and the viscous aerodynamic drag coefficient are obtained.

4. The method according to claim 2, characterized in that, Based on the aforementioned nonlinear control equations, and considering the unsteady aerodynamic loads on the blades as well as the gravity and inertial loads, the nonlinear dynamic response of the blades is obtained through iterative solution, including: Based on the blade's structural parameters, the tangential stiffness matrix of the blade structure is established by deriving the second-order transverse and longitudinal displacement fields and Green strain: ； in, Here is the tangent stiffness matrix. For the linear stiffness component, This refers to the portion with large deformation stiffness. This is the centrifugal tempering part; Obtain the mass parameters of the blade, and determine the mass matrix and structural damping matrix of the blade based on the mass parameters; The external load is obtained by adding the aerodynamic load to the blade's gravity load and inertial force load. Based on the external load, tangent stiffness matrix, mass matrix, and structural damping matrix, the nonlinear governing equations for the blades describing large structural deformations are established: ； in, This represents the blade displacement acceleration. Indicates the blade displacement velocity. Indicates the increment of blade displacement. For external loads, Here is the tangent stiffness matrix. For the quality matrix, Here is the structural damping matrix; The servo coordinate system is derived using the co-rotation coordinate method; Based on the servo coordinate system, establish the co-rotation transformation relationship between the internal element coordinate system and the global coordinate system of the blade to realize the description of the large rotation of the blade: ； in, This represents the moving coordinate system, which is the coordinate transformation matrix from the unit coordinate system to the global coordinate system. This represents the tangent stiffness matrix of the blade element; Within the framework of the modified Lagrange method, time-step integration is performed using the nonlinear Newmark-β method, and the nonlinear dynamic response of the blade is solved iteratively at each time step using the Newton-Raphson method.

5. The method according to claim 1, characterized in that, After calculating the aerodynamic load inputs for each structural element, the following is also included: Obtain wave parameters; Based on the higher-order spectral model and the wave parameters, the irregular incident waves acting on the floating platform are calculated. The nonlinear wave hydrodynamics of the floating platform under the wave-object interaction in the inner domain is calculated based on the time-domain fully nonlinear potential flow theory and the higher-order boundary element method.

6. The method according to claim 5, characterized in that, Based on the higher-order spectral model and the wave parameters, the irregular incident waves acting on the floating platform are calculated, including: The nonlinear free-surface boundary conditions are solved using the pseudospectral method to generate an incident wave field containing modulation instability: ； ； in, Vertical velocity, For convection terms, This is the static pressure recovery item. For dynamic pressure, It is a nonlinear coupling term; The incident wave field is reconstructed in three dimensions to obtain the incident wave horizontal velocity and horizontal velocity: ； ； in, The horizontal velocity of the incident wave, It is a horizontal position vector. For horizontal velocity, This is a two-dimensional inverse Fourier transform. The horizontal wavenumber vector, , To calculate the hyperbolic tangent, It is a three-dimensional velocity potential spectrum; The incident wave velocity field is interpolated to the inner domain boundary to determine the influence of the nonlinear evolution of the outer domain wave field on the nonlinear hydrodynamics of the inner domain.

7. The method according to claim 5, characterized in that, The nonlinear wave hydrodynamics of the floating platform under the wave-object interaction in the inner domain is calculated based on the time-domain fully nonlinear potential flow theory and the higher-order boundary element method, including: Establish the boundary integral equation: ； in, Let P be the velocity potential at the field point. The self-influence of the velocity potential at point P. For the Rankine Green's function, For the boundary velocity potential distribution, For boundary normal velocity perturbation, For boundary tangential velocity perturbation, Indicates the field point. Represents velocity potential, Indicates the source point, Represents the Green's function. Represents the normal derivative along the boundary. Indicates the integral boundary where the source point is located. This represents the fixed angle coefficient of the boundary integral equation at field point P; Discretize the boundary integral equation using the higher-order boundary element method; The scattering potential is calculated using the boundary integral equation. The total velocity potential is calculated using the scattering potential. The acceleration potential is calculated from the total velocity potential: ； in, For acceleration potential, The total velocity potential, This refers to the normal acceleration caused by the motion of the floating platform. This refers to the interaction between the motion of the floating platform and the fluid velocity gradient. For reference frame rotation correction, This represents the actual velocity of the fluid particles. For the translational acceleration of the floating platform, The rotational speed of the floating platform. The rotational acceleration of the floating platform, Let be the position vector of the floating platform surface. Let be the unit normal vector of the floating platform; Based on the acceleration potential, calculate the nonlinear wave hydrodynamics of the floating platform: ； in, This represents the nonlinear wave hydrodynamics of a floating platform. air density, The unit normal vector representing the boundary of the integral. Indicates the integral boundary where the field point is located. This refers to the static pressure distribution caused by fluid gravity. The pressure term represents the conversion of fluid kinetic energy.

8. The method according to any one of claims 5 to 7, characterized in that, After calculating the nonlinear wave hydrodynamics of the floating platform under the wave-object interaction in the inner domain based on the time-domain fully nonlinear potential flow theory and the higher-order boundary element method, the following is also included: Obtain the velocity and acceleration of the floating platform at the previous time step; The motion velocity and acceleration of the floating platform in the previous time step are transformed to the origin at the bottom of the tower through coordinate transformation, so as to calculate the motion response of each body structure of the target floating wind turbine under the motion of the floating platform according to the multibody dynamics equations of the current time step. The total load at the base of the tower at the current time step is transformed to the platform reference point through coordinate transformation. The total load at the base of the tower is calculated using aerodynamic load, inertial force load, gravity load, and damping load. The nonlinear wave hydrodynamics, viscous damping force, and mooring load of the floating platform are input into the platform's coupled motion equations to calculate the floating platform's motion response.

9. A simulation device for strong nonlinearity of large floating wind turbines, characterized in that, include: The acquisition module is used to acquire model parameters of the target floating wind turbine, wherein the model parameters include at least one of the following: shape parameters and mass parameters; The construction module is used to divide the target floating wind turbine into multiple body structures according to the model parameters, so as to construct a multibody model containing multiple degrees of freedom and establish the whole machine load and motion transmission path. The multiple body structures include at least one of the following: blades, wind turbine, nacelle, main shaft, yaw bearing, tower, and floating platform. A module is established to establish a local coordinate system for each structure based on the relative positional relationship of each structure in the target floating wind turbine, and to establish the coordinate transformation relationship of all structures of the whole machine from the local to the global coordinate system with the origin of the tower bottom as the reference origin of the global coordinate system. The first calculation module is used to calculate the aerodynamic load input of each body structure and to calculate the nonlinear dynamic response of the blade based on the aerodynamic load input of each body structure. The second calculation module is used to transform the nonlinear dynamic response of the blade to the global coordinate system through the coordinate transformation relationship and input it into the multibody dynamic model of the whole machine. It calculates the generalized active force and generalized inertial force of each body structure in the target floating wind turbine, and solves them simultaneously to obtain the motion response at each body structure of the target floating wind turbine. The calculation of aerodynamic load inputs for each structure includes: acquiring wind condition parameters for the operating area of ​​the target floating wind turbine; establishing a free vortex wake enhanced vortex grid aerodynamic model for the blades; calculating the unsteady aerodynamic loads of the three blades of the wind turbine based on the free vortex wake enhanced vortex grid aerodynamic model and the wind condition parameters; transforming the coordinates of the unsteady aerodynamic loads of the three blades to the wind turbine coordinate system and superimposing them to obtain the aerodynamic loads of the wind turbine; and sequentially transforming the coordinates of the aerodynamic loads of the wind turbine to each structure as the aerodynamic load inputs for each structure. The establishment of the free vortex wake-enhanced vortex lattice aerodynamic model for the blades includes: Based on the evolution and mutual influence of the blade attachment vortex and wake vortex, the induced velocity generated by the vortex at the blade control point is calculated. The free-flowing air velocity and the rigid body motion velocity of the target floating wind turbine in the global coordinate system are transformed to the blade coordinate system, and the total velocity at the control point is obtained by using the free-flowing air velocity, the rigid body motion velocity of the wind turbine, and the elastic deformation velocity of the blades. ； in, The total speed at the control point, For free-flow wind speed, The velocity of the rigid body of the wind turbine. The elastic deformation rate of the blade, For induced velocity, i represents the i-th control point of the vortex lattice on the blade lifting surface; Based on the impenetrable boundary assumption, the aerodynamic coefficient matrix of the influence of attached vortex and wake vortex on the induced velocity of the control point is determined. Based on the aerodynamic coefficient matrix, establish the velocity equation at the control point, and calculate the attached vortex intensity based on the velocity equation. ; Calculate the unsteady aerodynamic lift and unsteady aerodynamic drag of the blades using the following formulas: ； ； in, For unsteady aerodynamic lift of the blades, For unsteady aerodynamic drag of the blades, air density, For the airfoil chord, Based on effective angle of attack The obtained viscous aerodynamic lift coefficient, For the effective angle of attack of the airfoil, Based on effective angle of attack The obtained aerodynamic drag coefficient with viscosity was found. The length of the unit containing the airfoil. Based on the strength of the attached vortex The calculated unsteady induced drag is given by j, which represents the j-th wake vortex that detaches from the trailing edge of the blade.

10. A terminal device, comprising a processor and a memory for storing processor-executable instructions, characterized in that, When the processor executes the instructions, it implements the steps of the method according to any one of claims 1 to 8.

11. A computer-readable storage medium having a computer program / instructions stored thereon, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method according to any one of claims 1 to 8.

12. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method according to any one of claims 1 to 8.

Images