Floating fan mooring load calculation method and system based on coupling simulation

Abstract

The invention discloses a floating fan mooring load calculation method and system based on coupling simulation, and the method comprises the steps: obtaining the actual parameters of a floating fan, and constructing a first simulation model and a second simulation model in Charm3D and OpenFAST; collecting real ocean current data and configuring ocean current data of each time step length; inputting ocean current data into the two simulation models in real time, and inputting overall dynamic response data of the floating fan from the first simulation model into the second simulation model to obtain motion information of the floating fan; inputting the motion information of the floating fan into the first simulation model from the second simulation model to obtain new overall dynamic response data of the floating fan, and inputting the overall dynamic response data of the floating fan into the second simulation model again for simulation until the simulation period is finished; and mooring load data in the overall dynamic response data of the floating fan at each moment are obtained, and the time domain process of the mooring load of the floating fan is obtained. According to the method, the mooring load of the floating fan under the real ocean current condition of the open sea can be accurately calculated.

Description

Technical Field

[0001] The present invention relates to an analysis and calculation technology for offshore wind power infrastructure equipment, and in particular to a method and system for calculating the mooring load of a floating wind turbine based on coupling simulation. Background Art

[0002] With the continuous development of offshore wind power generation technology, floating wind turbines are also continuously developing in the open sea, which will face a more complex marine environment. The complexity of ocean current changes will also increase accordingly. Existing research often simplifies ocean currents into changes in flow velocity, which is seriously inconsistent with reality and will affect the calculation of mooring loads of floating wind turbines. Therefore, it is particularly important to develop an integrated tool that can accurately analyze the fully coupled dynamics of the mooring system and the floating platform.

[0003] The existing technical solution generally adopts the coupling simulation tool of Charm3D and OpenFAST. This coupling simulation tool mainly realizes coupling by transmitting the platform displacement and velocity through Charm3D, and then obtains the hydrodynamic load and mooring load through OpenFAST; however, Charm3D ignores the influence of platform acceleration and multi-physical field coupling effect, which will affect the result of mooring load. Summary of the invention

[0004] The technical problem to be solved by the present invention is as follows: In view of the above-mentioned problems in the prior art, a method and system for calculating the mooring load of a floating wind turbine based on coupling simulation is provided, which improves the coupling mode and introduces real ocean current data, so as to accurately calculate the mooring load in a complex marine environment.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: A method for calculating the mooring load of a floating wind turbine based on coupled simulation comprises the following steps: Acquire actual parameters of the floating wind turbine, construct a first simulation model in the Charm3D program according to the actual parameters of the floating wind turbine, and construct a second simulation model in the OpenFAST program according to the actual parameters of the floating wind turbine, wherein the first simulation model simulates to obtain overall dynamic response data of the floating wind turbine, and the second simulation model simulates to obtain motion information of the floating wind turbine; Collect real ocean current data, calculate the corresponding ocean current velocity profile distribution, and configure the ocean current data for each time step according to the ocean current velocity profile distribution data; Inputting the ocean current data into the first simulation model and the second simulation model in real time, inputting the overall dynamic response data of the floating wind turbine from the first simulation model into the second simulation model for simulation, obtaining the motion information of the floating wind turbine, and then inputting the motion information of the floating wind turbine from the second simulation model into the first simulation model for simulation, obtaining new overall dynamic response data of the floating wind turbine and inputting it into the second simulation model again for simulation, until the simulation cycle ends; The mooring load data in the overall dynamic response data of each floating wind turbine in the simulation period is obtained to obtain the time domain process of the mooring load of the floating wind turbine.

[0006] Furthermore, when collecting real ocean current data and calculating the corresponding ocean current velocity profile distribution, specifically after collecting ocean current velocity data from the surface to the bottom layer in the sea area where the floating wind turbine is located, the velocity difference between two adjacent layers of ocean current velocities is calculated and fitted to obtain a functional relationship between the velocity differences of the two adjacent layers, and data filling and data correction are performed on the blank areas and distorted areas of ocean current velocity measurement according to the functional relationship. Finally, the rules between the ocean current velocities of each layer are analyzed, and an empirical formula is constructed to calculate and obtain the ocean current velocity profile of the sea area where the floating wind turbine is located.

[0007] Furthermore, the empirical formula is expressed as follows:

[0008] In the formula, is the spatial location and time The speed of the current below; It is order space modes; It is The time coefficient corresponding to the order space mode; is the cutoff order.

[0009] Furthermore, when constructing the first simulation model in the Charm3D program according to the actual parameters of the floating wind turbine, specifically, constructing the geometric model and physical characteristics of the floating wind turbine in the Charm3D program according to the actual parameters of the floating wind turbine, and defining the environmental load, assuming the floating wind turbine to be a rigid body moving in waves, ambient wind and ocean currents to construct the motion equation, and at the same time modeling the mooring cable as a high-order finite element model and establishing the control equation of the mooring cable; when inputting the motion information of the floating wind turbine from the second simulation model into the first simulation model for simulation, it includes: converting the format of the motion information of the floating wind turbine and then inputting it into the motion equation, and at the same time solving the control equation of the mooring cable, and using the calculation results of the motion equation and the solution results of the control equation of the mooring cable as the overall dynamic response data of the floating wind turbine.

[0010] Furthermore, the motion equation is expressed as follows:

[0011] In the formula, and They are the actual mass of the floating fan and the additional mass due to fluid motion under high-frequency vibration; is the wave force in the overall dynamic response data of the floating wind turbine, is the radiation damping force in the overall dynamic response data of the floating wind turbine, is the nonlinear viscous drag force in the overall dynamic response data of the floating wind turbine, is the mooring restoring force in the overall dynamic response data of the floating wind turbine, is the buoyancy in the overall dynamic response data of the floating wind turbine, is the inertial force in the overall dynamic response data of the floating wind turbine; It is the platform freedom data in the floating wind turbine motion information; and The velocity data and acceleration data of the floating wind turbine motion information are respectively. Furthermore, the control equation of the mooring cable is expressed as:

[0012]

[0013]

[0014] In the formula, represents the bending stiffness of the mooring line, is the position vector, is Young's modulus, is the moment of inertia of the area, is the distributed load, is the mooring line density, is the Lagrange multiplier, It's tension. is the effective cross-sectional area, the prime is the derivative with respect to arc length, and the dot is the derivative with respect to time.

[0015] Furthermore, when constructing a second simulation model in the OpenFAST program according to the actual parameters of the floating wind turbine, specifically, constructing a geometric model and physical characteristics of the floating wind turbine in the OpenFAST program according to the actual parameters of the floating wind turbine, defining environmental loads, and establishing generalized dynamic equations; when inputting the overall dynamic response data of the floating wind turbine from the first simulation model into the second simulation model for simulation, it includes: converting the format of the overall dynamic response data of the floating wind turbine and then inputting it into the generalized dynamic equations and solving them to obtain the motion information of the floating wind turbine.

[0016] Furthermore, the generalized kinetic equation is as follows:

[0017]

[0018] In the formula, is the generalized displacement vector of the platform degree of freedom data in the floating wind turbine motion information, is the generalized velocity vector of the velocity data in the motion information of the floating wind turbine, is the generalized acceleration vector of the acceleration data in the floating wind turbine motion information, are the Coriolis and centripetal force matrices, is the vector of generalized forces, is the generalized inertial force vector of the overall dynamic response data of the floating wind turbine, It is the generalized active force vector of the overall dynamic response data of the floating wind turbine.

[0019] Furthermore, the expression of the generalized active force is as follows:

[0020] In the formula, is the generalized main driving force, It is the hydrodynamic force in the overall dynamic response data of the floating wind turbine, including the radiation damping force and nonlinear viscous drag force in the overall dynamic response data of the floating wind turbine. is the mooring restoring force in the overall dynamic response data of the floating wind turbine, is the wave force in the overall dynamic response data of the floating wind turbine, is the buoyancy in the overall dynamic response data of the floating wind turbine.

[0021] The present invention also proposes a floating wind turbine mooring load calculation system based on coupled simulation, comprising a microprocessor and a computer-readable storage medium connected to each other, wherein the microprocessor is programmed or configured to execute the steps of the floating wind turbine mooring load calculation method based on coupled simulation.

[0022] Compared with the prior art, the advantages of the present invention are: The present invention improves the coupling mode of the Charm3D program and the OpenFAST program. The first simulation model in the Charm3D program transmits the overall dynamic response data of the floating wind turbine, such as hydrodynamic force, wave force and platform response, to the OpenFAST program. The second simulation model in the OpenFAST program then calculates and updates the floating wind turbine motion information data, such as the displacement, velocity and acceleration of the six degrees of freedom of the floating wind turbine platform. Finally, the real ocean current data is put into the coupling model, and the mooring cable of the underwater structure of the floating wind turbine can be simulated in a more realistic situation, so as to obtain a more accurate mooring load. Through the above improvements, Charm3D and OpenFAST can better simulate the dynamic response of the floating wind turbine in a complex marine environment, and the accurate situation of the mooring system under the influence of the real ocean current in the open sea. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 1 is a flowchart of the steps of the method according to an embodiment of the present invention.

[0024] Figure 2 It is a schematic diagram of the simplified floating body-mooring coupling dynamics of the Charm3D program in an embodiment of the present invention.

[0025] Figure 3 It is a cross-sectional view of a certain sea area when the current velocity is 1.0 m / s in an embodiment of the present invention.

[0026] Figure 4 It is a coupling calculation flow chart in an embodiment of the present invention.

[0027] Figure 5 It is a diagram of wind speed and wave height at the hub of a floating wind turbine when calculating the mooring load of a floating wind turbine platform in an embodiment of the present invention.

[0028] Figure 6 This is a diagram of the tension at the top of the mooring cable with and without sea current when calculating the mooring load of the floating wind turbine platform in an embodiment of the present invention.

[0029] Figure 7 This is a diagram of the tension at the bottom of the mooring cable with and without sea current when calculating the mooring load of the floating wind turbine platform in an embodiment of the present invention.

[0030] Figure 8 It is a mooring tension diagram of the mooring cable at different positions when calculating the mooring load of the floating wind turbine platform in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0032] Embodiment 1 As the ocean environment becomes more and more complex, the complexity of ocean current changes also increases. Currently, in the Charm3D and OpenFAST coupling simulation tools, Charm3D ignores the influence of platform acceleration and multi-physics field coupling effects, while platform acceleration will directly affect the inertial load of the wind turbine.

[0033] In order to solve the above problems, this embodiment proposes a floating wind turbine mooring load calculation method based on coupled simulation, introduces the calculation of platform acceleration in the coupled model, improves the coupling mode of Charm3D and OpenFAST, and transmits the overall dynamic response data of the floating wind turbine such as hydrodynamic force, wave force and platform response to OpenFAST by Charm3D, and then calculates and updates the floating wind turbine motion information data such as displacement, velocity and acceleration of the six degrees of freedom of the floating wind turbine platform in OpenFAST; finally, the two-way data exchange is realized, and the accurately calculated mooring load is obtained in the Charm3D output data. In addition, the dynamic equations of Charm3D and OpenFAST are modified to realize the calculation of offshore wind turbine mooring loads under real ocean current conditions in offshore environments.

[0034] like Figure 1 As shown, the method of this embodiment includes the following steps: S1) obtaining actual parameters of the floating wind turbine, constructing a first simulation model in the Charm3D program according to the actual parameters of the floating wind turbine, and constructing a second simulation model in the OpenFAST program according to the actual parameters of the floating wind turbine, wherein the first simulation model simulates to obtain overall dynamic response data of the floating wind turbine, and the second simulation model simulates to obtain motion information of the floating wind turbine; S2) Collecting real ocean current data, calculating the corresponding ocean current velocity profile distribution, and configuring ocean current data for each time step according to the ocean current velocity profile distribution data; S3) inputting the ocean current data into the first simulation model and the second simulation model in real time, inputting the overall dynamic response data of the floating wind turbine from the first simulation model into the second simulation model for simulation, obtaining the motion information of the floating wind turbine, and then inputting the motion information of the floating wind turbine from the second simulation model into the first simulation model for simulation, obtaining new overall dynamic response data of the floating wind turbine and inputting it into the second simulation model again for simulation, until the simulation cycle ends; S4) obtaining the mooring load data in the overall dynamic response data of each floating wind turbine in the simulation period, and obtaining the time domain process of the mooring load of the floating wind turbine.

[0035] The above steps are further explained below by taking an offshore wind farm as an example.

[0036] In this embodiment, through step S1, actual parameters of the floating wind turbine are obtained from standards and specifications, and then calculation models of the floating wind turbine are respectively constructed in Charm3D and OpenFAST according to these parameters, including the following steps: S11: Collect the parameters of floating wind turbines by consulting data and literature. The main data to be collected include: overall parameters of floating wind turbines, parameters of wind turbine blades, parameters of wind turbine transmission system, parameters of floating platform and supporting structure; Based on the actual parameters of floating wind turbines, construct calculation models of floating wind turbines in Charm3D and OpenFAST respectively, which are mainly used for accurate calculation of mooring loads of floating wind turbines; S12: According to the actual simulation situation, the Charm3D parameters obtained in the frequency domain by the three-dimensional diffraction / radiation preprocessor include the information of the floating wind turbine (coupling relationship between the platform and the mooring system, boundary conditions of the mooring line, etc.) and the input command and control parameters related to the operation of the wind turbine, as well as fluid dynamics data, waves, etc.

[0037] In step S11, when constructing the calculation model of the floating wind turbine in Charm3D and OpenFAST respectively, it includes: S111) constructing a first simulation model in the Charm3D program according to actual parameters of the floating wind turbine, specifically, constructing a geometric model and physical characteristics of the floating wind turbine in the Charm3D program according to the actual parameters of the floating wind turbine, and defining environmental loads, such as the effects of waves, currents, wind, etc. on the floating body, assuming the floating wind turbine to be a rigid body moving in waves, environmental wind and currents to construct motion equations, and at the same time modeling the mooring cable as a high-order finite element model and establishing control equations for the mooring cable.

[0038] Specifically, Figure 2 As shown in the figure, wind loads, first-order (second-order) wave loads, current loads, mooring cable hydrodynamics, mooring cable inertia and resistance, and seabed interactions are taken into account in Charm3D simulation in order to fully simulate the dynamic response of offshore wind turbines in complex marine environments, which is crucial for calculating the mooring loads of floating wind turbine platforms.

[0039] In Charm3D, the floating platform is assumed to be a rigid body moving in waves, ambient wind and currents, and the mooring cable is modeled as a high-order finite element model; the dynamics of the mooring cable due to wave kinematics and its inertia and resistance can also be included in the analysis. The entire mooring motion is solved simultaneously in the combined system matrix at each time step. In this embodiment, the platform motion equations of the coupled floating wind turbine are modified. The prior art of Charm3D usually assumes that the influence of the platform acceleration on the hydrodynamic force is negligible, and also through the addition of mass The inertial effect is implicitly included, and the fluid inertial response is "staticized", which simplifies the calculation, but the accuracy of the mooring load calculation is not enough. The method of this embodiment requires a more accurate mooring load, so an explicit separation inertial force term is tried. , which can avoid the existing technology to add quality The approximate processing of can also be used to correct the platform motion in the iterative solution, and finally obtain a more reliable result; the platform motion equation of the corrected floating wind turbine is:

[0040] Where: and They are the actual mass of the floating fan and the additional mass due to fluid motion under high-frequency vibration; It is the wave force; is the radiation damping force; is the nonlinear viscous drag force; is the mooring restoring force; It is buoyancy; is the inertial force; It is the platform freedom data in the floating wind turbine motion information; and The velocity data and acceleration data of the floating wind turbine motion information are respectively.

[0041] In addition, the governing equations for the mooring cable are:

[0042]

[0043]

[0044] In the formula, represents the bending stiffness of the mooring line, is the position vector, is Young's modulus, is the moment of inertia of the area, is the distributed load, is the mooring line density, is the Lagrange multiplier, It's tension. is the effective cross-sectional area, the prime is the derivative with respect to arc length (s), and the dot is the derivative with respect to time (t).

[0045] The mooring load of a floating wind turbine is the total load borne by the mooring cable in a dynamic marine environment, which mainly includes: the mooring tension of the mooring cable , stress caused by bending deformation of mooring cables and distributed loads on mooring lines Therefore, by solving the coupling equation of motion of the floating wind turbine platform and the mooring cable, the tension of the mooring cable can be directly obtained. and distributed loads , indirectly through The bending stress is obtained, where the curvature is the position vector The second derivative of The mooring load data in the time domain is obtained by further synthesis.

[0046] S112) When constructing the second simulation model in the OpenFAST program according to the actual parameters of the floating wind turbine, specifically, constructing the geometric model and physical characteristics of the floating wind turbine in the OpenFAST program according to the actual parameters of the floating wind turbine, and also defining the environmental load, and establishing the generalized dynamic equation.

[0047] Specifically, OpenFAST uses the transmitted force to fill the forcing function of the platform's degrees of freedom to drive the movement of the platform; then by configuring the platform's physical properties and other relevant parameters, OpenFAST can perform accurate numerical simulation, calculate and obtain the displacement, velocity and acceleration of the floating wind turbine platform's six degrees of freedom at the current moment as the floating wind turbine motion information; these six degrees of freedom are: positive displacement along the x-axis (Surge), positive displacement along the y-axis (Sway), positive displacement along the z-axis (Heave), rotation around the x-axis (Roll), rotation around the y-axis (Pitch) and rotation around the z-axis (Yaw).

[0048] OpenFAST uses Kane dynamics to describe the dynamic behavior of the floating wind turbine platform. In this embodiment, a generalized dynamic equation of the platform is established to achieve a detailed analysis of the platform motion. By solving this equation, the displacement, velocity and acceleration data of the floating wind turbine platform at each moment can be obtained, thereby re-analyzing the dynamic response of the floating wind turbine. The equation is as follows:

[0049]

[0050] In the formula, is the generalized displacement vector of the platform degree of freedom data in the floating wind turbine motion information, is the generalized velocity vector of the velocity data in the motion information of the floating wind turbine, is the generalized acceleration vector of the acceleration data in the floating wind turbine motion information, are the Coriolis and centripetal force matrices, is the vector of generalized forces, is the generalized inertial force vector of the overall dynamic response data of the floating wind turbine, It is the generalized active force vector of the overall dynamic response data of the floating wind turbine, including the generalized active force transmitted by Charm3D and other active forces (including aerodynamic force, elastic force, generator force and damping force, etc.).

[0051] In this embodiment, in step S2, the ocean current data is collected in the sea area where the floating wind turbine is located, and an empirical formula is constructed based on the data to describe the distribution of the ocean current profile. By putting the real ocean current data into the coupling model, the mooring cable of the underwater structure of the floating wind turbine can be simulated in a more realistic situation, and a more accurate mooring load can be obtained, which includes the following steps: S21) After collecting the ocean current velocity data from the surface layer to the bottom layer in the sea area where the floating wind turbine is located, the velocity difference between two adjacent layers of ocean current velocity is calculated and fitted to obtain a functional relationship between the velocity differences of the two adjacent layers, and data filling and data correction are performed on the ocean current velocity measurement blank area and distortion area according to the functional relationship. Finally, the regularity between the ocean current velocities of each layer is analyzed, and an empirical formula is constructed to calculate and obtain the ocean current velocity profile of the sea area where the floating wind turbine is located.

[0052] As floating wind turbines continue to develop in the open sea, considering that the complexity of open sea currents increases with depth, in the past, the currents were only simplified to simple velocity changes, and relatively simple current profile models such as uniform flow or shear flow were used. This can no longer meet the actual response of the mooring system in the open sea; the method of this embodiment uses an acoustic Doppler current profiler (ADCP), buoy data, and ocean observation station data, including vertical velocity distribution (velocity changes from the surface to the bottom), surface velocity, middle and bottom layer velocity, and time series data of velocity and direction; and then uses real current data to construct an empirical formula to describe the current profile.

[0053] However, the accuracy of the ocean current used to construct the empirical formula places high demands on the quality of the measured data, and the density of the sediment medium on the seabed will affect the measurement of the seabed flow velocity. The instrument measurement will also have certain blind spots, and the flow velocity in the blind spots cannot be measured. Therefore, this embodiment adopts a method of stratifying the ocean current: first, the velocity difference between the flow velocities of adjacent layers is calculated, and these velocities are fitted, and then the relationship between the velocity differences of two adjacent layers is deduced, and finally the law between the velocities of the ocean current stratification is found; after improving and supplementing the blank areas and distorted areas of the ocean current velocity measurement, the processed data is mathematically fitted to construct an empirical formula to describe the distribution of the ocean current profile.

[0054] When constructing an empirical formula to describe the distribution of the ocean current profile, it includes but is not limited to empirical orthogonal function (EOF) decomposition, exponential decay model, power law model and segment model, etc. This embodiment describes the distribution of the ocean current profile based on the empirical orthogonal function (EOF), and the empirical orthogonal function (EOF) formula is:

[0055] In the formula, is the spatial location and time The speed of the current below; It is The order spatial modes (spatial components of EOF); It is The time coefficient corresponding to the order space mode; is the cutoff order, indicating the number of EOF modes retained; Through the above steps, we can get Figure 3 The current velocity profile based on the empirical orthogonal function (EOF) in the sea area where the floating wind turbine is located is shown.

[0056] S22) converting the ocean current data in the ocean current velocity profile obtained by constructing the empirical formula into a matrix form, and setting the converted matrix to a specified resolution to obtain ocean current data for each time step.

[0057] Specifically, the ocean current data obtained by constructing the empirical formula is maintained in a matrix form (such as a .mat file) using the Matlab programming program. Since the main input data of the coupling software is a 0.05 second resolution, the ocean current data is read using the Matlab programming program for format conversion, and then the data is processed again for resolution to meet the input requirements of the coupling software. This controls the actual ocean current conditions in each time step, so that Charm3D and OpenFAST can obtain the actual ocean current conditions.

[0058] This embodiment implements the coupling simulation process of the first simulation model in the Charm3D program and the second simulation model in the OpenFAST program through step S3, such as Figure 4 As shown, specifically including: S31) Simulating the first simulation model.

[0059] After configuring the ocean current data file, the corresponding environmental wind, wave and other data are input into the Charm3D program, and the motion information of the floating wind turbine is obtained to simulate the first simulation model, thereby obtaining the overall dynamic response data of the floating wind turbine at the previous moment.

[0060] In this embodiment, the overall dynamic response data of the floating wind turbine is obtained by simultaneously calculating the platform motion equation of the floating wind turbine and solving the control equation of the mooring cable. The overall dynamic response data of the floating wind turbine includes data on hydrodynamics, wave force, platform motion, structural stress, blade load, and mooring load, that is, the wave force in the platform motion equation of the floating wind turbine , radiation damping force , nonlinear viscous drag force , mooring restoring force , inertial force These data are obtained by substituting the floating wind turbine motion information into the floating platform motion equation in real time and updating the corresponding variables and then performing corresponding calculations, where: Wave force The wave pressure distribution is calculated through time domain simulation, and the force exerted by the waves on the floating wind turbine platform is obtained by integration; Radiation Damping Force is the fluid reaction force caused by the movement of the floating wind turbine platform, which is calculated by the frequency domain radiation damping kernel function, and the velocity It will directly affect the amplitude and phase of the damping force; Nonlinear viscous drag force Through the Morison equation (depending on the platform speed The difference between the velocity of the fluid and the velocity of the floating wind turbine platform is calculated by calculating the resistance of the fluid viscosity to the floating wind turbine platform; Mooring recovery force According to the displacement of the floating wind turbine platform Determine the geometric shape and tension distribution of the mooring cable, and then use the high-order finite element method to calculate the control force on the floating wind turbine platform. Specifically, under the control equation of the mooring cable, solve the tension of the mooring cable and the stress distribution of the mooring line, and then the tension of the mooring line and distributed loads This directly translates into mooring recovery forces for floating wind turbine platforms; buoyancy The magnitude and direction of the floating wind turbine platform change with displacement Changes, depending on the displacement of the floating wind turbine platform provided The hydrostatic pressure distribution at different locations can be analyzed, and the buoyancy generated by the hydrostatic pressure can be calculated; Inertial force is the acceleration of the floating wind turbine platform delivered by OpenFAST Calculated, that is:

[0061] in, It is the actual mass of the floating fan under high frequency vibration.

[0062] It should be noted that, at the initial moment, the floating wind turbine motion information obtained by the first simulation model is the initial value of the preset platform degree of freedom data, velocity data and acceleration data. In the subsequent coupling iterations, the platform degree of freedom data, velocity data and acceleration data transmitted by OpenFAST are used to replace the initial values.

[0063] S32) inputting the overall dynamic response data of the floating wind turbine from the first simulation model into the second simulation model for simulation.

[0064] In this embodiment, the data of the previous moment obtained by the simulation of the first simulation model of the Charm3D program is saved in binary format (such as .csv); then, the output data of the Charm3D program is read by the Matlab programming program, and the key data required for coupling is extracted and made into the input file required by the OpenFAST program (such as .fst file); ensure that the second simulation model of the OpenFAST program can accurately use the converted data to continue the OpenFAST simulation, so as to realize the accurate simulation of the floating wind turbine platform in the complex marine environment.

[0065] The specific situation is: Charm3D inputs the forces required by the platform into OpenFAST, including hydrodynamics, wave forces, and platform responses. The platform responses include mooring restoring forces and hydrostatic restoring forces. Mooring restoring forces refer to the forces / torques exerted by the mooring system on the platform. Hydrostatic restoring forces refer to the forces caused by changes in buoyancy, specifically the buoyancy increments generated by changes in the submerged volume of the floating platform under external loads, which prompt the platform to return to its equilibrium position. These forces in the overall dynamic response data of the floating wind turbine are correctly input into the generalized active forces in the generalized dynamic equations after format conversion, and their expressions are as follows:

[0066] In the formula, is the generalized main driving force, is the hydrodynamic force in the overall dynamic response data of the floating wind turbine, including the radiation damping force in the overall dynamic response data of the floating wind turbine and nonlinear viscous drag , is the mooring restoring force in the overall dynamic response data of the floating wind turbine, is the wave force in the overall dynamic response data of the floating wind turbine, It is the buoyancy in the overall dynamic response data of the floating wind turbine. The buoyancy and the model's own weight jointly determine the static stability of the platform.

[0067] S33) solving the generalized dynamic equation to obtain the displacement, velocity and acceleration data of the six degrees of freedom of the floating wind turbine platform at the current moment, thereby obtaining the motion information of the floating wind turbine at the current moment; S34) Inputting the floating wind turbine movement information from the second simulation model into the first simulation model for simulation.

[0068] Specifically, the floating wind turbine motion information data (platform degrees of freedom, speed and acceleration, etc.) at the current moment is converted into a format through the Matlab programming program to compensate for the influence of the platform acceleration that Charm3D will ignore, and then the converted data is substituted into the motion equation to replace the corresponding variables to continue the simulation calculation at the next moment. The specific calculation process is the same as step S31, so as to obtain further dynamic responses of the floating wind turbine platform, including the platform motion, structural stress, blade load and mooring load at the next moment, and other overall dynamic response data of the floating wind turbine at the next moment.

[0069] Steps S31 to S34 will be repeated continuously until the dynamic response analysis within the entire simulation cycle is completed.

[0070] In this embodiment, the time domain process of the mooring load of the floating wind turbine platform is obtained through step S4, specifically, the data of the mooring load of the floating wind turbine overall dynamic response data at each moment in the entire simulation cycle is obtained, such as the mooring tension at each moment. .like Figures 5 to 8 As shown, from Figure 5 It can be seen that the floating wind turbine is subject to external environmental conditions; Figure 6 and Figure 7 It can be seen that in the case of ocean currents, the tension on the mooring cable is significantly greater at both the top and bottom ends; Figure 8 It can be seen that the tension of the mooring cable at different positions is also significantly different. It can be seen that the method of this embodiment makes a more optimized model for the mooring tension of the offshore wind turbine platform, and improves the calculation efficiency of the mooring system.

[0071] Embodiment 2 This embodiment proposes a floating wind turbine mooring load calculation system based on coupled simulation, including a microprocessor and a computer-readable storage medium connected to each other, wherein the microprocessor is programmed or configured to execute the steps of the floating wind turbine mooring load calculation method based on coupled simulation described in the first embodiment.

[0072] In summary, the present invention proposes a method for calculating the mooring load of a floating wind turbine based on coupled simulation, and designs a system for executing the steps of the proposed method, which can be used to calculate the mooring load under complex ocean currents in the open sea, and to simulate the dynamic behavior of the mooring cable of a floating wind turbine. The present invention does not simplify the ocean current conditions in the open sea into simple flow velocity changes as in the past, but collects actual data and couples it into the simulation, and improves the coupling method, and completes the accurate calculation of the mooring load of the floating wind turbine platform by analyzing the condition of the mooring system in real time. The present invention makes a more optimized model for the mooring tension of the offshore wind turbine platform, and improves the calculation efficiency of the mooring system condition.

[0073] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for calculating the mooring load of a floating wind turbine based on coupled simulation, characterized in that: The following steps are involved: Acquire actual parameters of the floating wind turbine, construct a first simulation model in the Charm3D program according to the actual parameters of the floating wind turbine, and construct a second simulation model in the OpenFAST program according to the actual parameters of the floating wind turbine, wherein the first simulation model simulates to obtain overall dynamic response data of the floating wind turbine, and the second simulation model simulates to obtain motion information of the floating wind turbine; Collect real ocean current data, calculate the corresponding ocean current velocity profile distribution, and configure the ocean current data for each time step according to the ocean current velocity profile distribution data; Inputting the ocean current data into the first simulation model and the second simulation model in real time, inputting the overall dynamic response data of the floating wind turbine from the first simulation model into the second simulation model for simulation, obtaining the motion information of the floating wind turbine, and then inputting the motion information of the floating wind turbine from the second simulation model into the first simulation model for simulation, obtaining new overall dynamic response data of the floating wind turbine and inputting it into the second simulation model again for simulation, until the simulation cycle ends; The mooring load data in the overall dynamic response data of each floating wind turbine in the simulation period is obtained to obtain the time domain process of the mooring load of the floating wind turbine.

2. The method for calculating the mooring load of a floating wind turbine based on coupled simulation according to claim 1 is characterized in that: When collecting real ocean current data and calculating the corresponding ocean current velocity profile distribution, specifically after collecting ocean current velocity data from the surface to the bottom layer in the sea area where the floating wind turbine is located, the velocity difference between two adjacent layers of ocean current velocities is calculated and fitted to obtain the functional relationship between the velocity differences of the two adjacent layers, and data filling and data correction are performed on the blank areas and distorted areas of ocean current velocity measurement according to the functional relationship. Finally, the rules between the ocean current velocities of each layer are analyzed, and an empirical formula is constructed to calculate and obtain the ocean current velocity profile of the sea area where the floating wind turbine is located.

3. The method for calculating the mooring load of a floating wind turbine based on coupled simulation according to claim 2 is characterized in that: The empirical formula is expressed as follows: In the formula, is the spatial location and time The speed of the current below; It is order space modes; It is The time coefficient corresponding to the order space mode; is the cutoff order.

4. The method for calculating the mooring load of a floating wind turbine based on coupled simulation according to claim 1, characterized in that: When constructing the first simulation model in the Charm3D program according to the actual parameters of the floating wind turbine, specifically, constructing the geometric model and physical characteristics of the floating wind turbine in the Charm3D program according to the actual parameters of the floating wind turbine, defining the environmental load, assuming the floating wind turbine to be a rigid body moving in waves, environmental wind and ocean currents to construct the platform motion equation of the floating wind turbine, and at the same time modeling the mooring cable as a high-order finite element model and establishing the control equation of the mooring cable; When the floating wind turbine motion information is input from the second simulation model into the first simulation model for simulation, the method includes: converting the floating wind turbine motion information into a format and then inputting it into the platform motion equation for calculation, while coupling and solving the control equation of the mooring cable and the platform motion equation, and using the motion equation calculation results and the coupling solution results as the overall dynamic response data of the floating wind turbine.

5. The method for calculating the mooring load of a floating wind turbine based on coupled simulation according to claim 4 is characterized in that: The equation of motion is expressed as follows: In the formula, and They are the actual mass of the floating fan and the additional mass due to fluid motion under high-frequency vibration; is the wave force in the overall dynamic response data of the floating wind turbine, is the radiation damping force in the overall dynamic response data of the floating wind turbine, is the nonlinear viscous drag force in the overall dynamic response data of the floating wind turbine, is the mooring restoring force in the overall dynamic response data of the floating wind turbine, is the buoyancy in the overall dynamic response data of the floating wind turbine, is the inertial force in the overall dynamic response data of the floating wind turbine; It is the platform freedom data in the floating wind turbine motion information; and The velocity data and acceleration data of the floating wind turbine motion information are respectively.

6. The method for calculating the mooring load of a floating wind turbine based on coupled simulation according to claim 4 is characterized in that: The control equation of the mooring cable is expressed as: In the formula, represents the bending stiffness of the mooring line, is the position vector, is Young's modulus, is the moment of inertia of the area, is the distributed load, is the mooring line density, is the Lagrange multiplier, It's tension. is the effective cross-sectional area, the prime is the derivative with respect to arc length, and the dot is the derivative with respect to time.

7. The method for calculating the mooring load of a floating wind turbine based on coupled simulation according to claim 1, characterized in that: When constructing the second simulation model in the OpenFAST program according to the actual parameters of the floating wind turbine, specifically, constructing the geometric model and physical characteristics of the floating wind turbine in the OpenFAST program according to the actual parameters of the floating wind turbine, defining the environmental load, and establishing the generalized dynamic equation; When the overall dynamic response data of the floating wind turbine is input from the first simulation model to the second simulation model for simulation, the method includes: converting the overall dynamic response data of the floating wind turbine into a format and then inputting it into a generalized dynamic equation and solving it to obtain the motion information of the floating wind turbine.

8. The method for calculating the mooring load of a floating wind turbine based on coupled simulation according to claim 7 is characterized in that: The generalized kinetic equation is shown below: In the formula, is the generalized displacement vector of the platform degree of freedom data in the floating wind turbine motion information, is the generalized velocity vector of the velocity data in the motion information of the floating wind turbine, is the generalized acceleration vector of the acceleration data in the floating wind turbine motion information, are the Coriolis and centripetal force matrices, is the vector of generalized forces, is the generalized inertial force vector of the overall dynamic response data of the floating wind turbine, It is the generalized active force vector of the overall dynamic response data of the floating wind turbine.

9. The method for calculating the mooring load of a floating wind turbine based on coupled simulation according to claim 8, characterized in that: The expression of generalized active force is as follows: In the formula, is the generalized main driving force, It is the hydrodynamic force in the overall dynamic response data of the floating wind turbine, including the radiation damping force and nonlinear viscous drag force in the overall dynamic response data of the floating wind turbine. is the mooring restoring force in the overall dynamic response data of the floating wind turbine, is the wave force in the overall dynamic response data of the floating wind turbine, is the buoyancy in the overall dynamic response data of the floating wind turbine.

10. A floating wind turbine mooring load calculation system based on coupled simulation, characterized in that: The invention comprises a microprocessor and a computer-readable storage medium connected to each other, wherein the microprocessor is programmed or configured to execute the steps of the method for calculating the mooring load of a floating wind turbine based on coupled simulation according to any one of claims 1 to 9.

Images