Complete machine load simulation calculation method for parallel type double-wind-turbine-generator floating type wind power equipment

Abstract

The invention relates to the technical field of offshore floating type wind power generation, and provides a complete machine load simulation calculation method for parallel type double wind turbine generator floating type wind power equipment. According to the blade aerodynamic load, the platform hydrodynamic load, the tower structure deformation and the blade structure deformation of the double-wind-turbine-generator floating type wind power equipment and design parameters required by system control, a wind field environment is defined, and the aerodynamic loads of the two wind turbine generators are calculated. And constructing a load transformation matrix of the two wind turbine generators, and adding the transformed loads to obtain a total load vector of the two wind turbine generators to the platform. And according to the radiation diffraction effect of the double-wind-turbine-generator floating type wind power equipment platform, the hydrodynamic load and the mooring restoring force of the platform are calculated. And calculating real-time coordinates, speeds and accelerations of blades of the two wind turbine generators according to the inclination angles of the two wind turbine generators. The nonlinear structure dynamic response of the novel wind energy conversion system for offshore floating type wind power generation under the action of wind, wave and flow loads is accurately calculated.

Description

Technical Field

[0001] The present invention belongs to the technical field of offshore floating wind power generation, and in particular relates to a whole machine load simulation calculation method for a parallel dual wind turbine floating wind power equipment. Background Art

[0002] Compared with onshore wind power, there is no land restriction in developing wind energy resources in deep-sea systems, and the ocean wind energy density is higher and the wind speed is more stable, which is the development direction of large-scale wind power equipment. Floating wind power equipment is to install conventional wind turbines on floating platforms to utilize the rich wind energy resources in deep sea areas.

[0003] At present, floating wind turbines have entered the commercialization or commercial demonstration stage, and all of them use a single wind turbine combined with a single floating platform. Due to the harsh marine environment, in order to ensure the stable operation and structural safety of wind turbines, the floating platform is extremely large, and a mooring system with multiple anchor chains is also installed, resulting in high costs for floating wind power. The cost per kilowatt-hour of multiple floating wind turbines demonstrated in my country is three to six times that of fixed kilowatt-hours. Therefore, floating wind power has not yet developed on a large scale.

[0004] In order to reduce the cost of floating wind power, multiple wind turbines can be installed on one platform. By making full use of the floating platform and mooring system, the overall cost of floating wind power can be reduced. Among them, the floating wind power equipment with two wind turbines installed in parallel is the most promising. Due to the parallel installation method, there is no significant aerodynamic interference problem between the two wind turbines, and high aerodynamic performance can be maintained.

[0005] However, the floating wind power equipment with two wind turbines is a new type of wind power generation equipment, and no in-depth research has been carried out so far. The main reason is the lack of a reliable whole-machine load simulation calculation method that can consider the structural dynamic response coupling and coordinated control of the two wind turbines.

[0006] CN111997842B discloses a method for installing a tower and main engine of a floating dual-rotor wind turbine generator set, and provides the installation sequence and specific lifting method of each structural component of this type of new floating wind power equipment, but does not explain how to calculate the movement of the platform under the action of wind, wave and current loads and the structural load of the wind turbine set.

[0007] CN113653603A discloses a dual-wind-rotor automatic yaw power generation system and a yaw control method thereof, the invention comprises a wind turbine, a platform, a mooring system and a yaw controller. There are two wind turbines, which are installed on the tower in an inclined form. The yaw control of the whole machine is achieved through a propeller yaw device.

[0008] CN117189458A discloses a parallel double-rotor wind turbine set and a control method. The two wind turbine sets rotate in opposite directions and retain a certain distance between them. However, the invention is a fixed onshore wind turbine set.

[0009] Although the above two inventions disclose some appearance design schemes and some simple control methods for parallel dual-rotor wind turbines, they do not mention how to calculate the complete machine load of the wind energy equipment of the parallel dual-rotor wind turbines. It is difficult to evaluate the load level, motion performance and power generation efficiency of the dual-unit floating wind power equipment based on the currently disclosed technology or software, which greatly limits the development of this type of new floating wind power system. Summary of the invention

[0010] In view of the shortcomings of the prior art, the present invention provides a method for simulating and calculating the load of a floating wind power equipment with parallel dual wind turbines, comprising the following steps:

[0011] Step S1: The aerodynamic loads of blades of the floating wind power equipment with dual wind turbines, the hydrodynamic loads of the platform, the deformation of the tower structure and the deformation of the blade structure, as well as the design parameters required for system control are given.

[0012] Step S2: define the wind farm environment, calculate the aerodynamic loads of the two wind turbines, and calculate the tower load vectors F1, M1 and F2, M2 of the two wind turbines at the tower base according to the structural deformation of the tower.

[0013] Step S3: Based on the roll θ1, pitch θ2 and bow pitch θ3 of the floating wind power equipment platform with two wind turbines at the current moment, and the inclination angles α1 and α2 of the two wind turbines, the load transformation matrices T1 and T2 of the two wind turbines are constructed.

[0014] Step S4: transform the tower load vectors of the two wind turbines from the local coordinate system to the global coordinate system, and transfer the load action point from the tower base to the intersection of the still water surface and the central axis of the platform, and add the transformed loads to obtain the total load vector F of the two wind turbines on the platform 合 、M 合 .

[0015] Step S5: Calculate the platform hydrodynamic load and mooring restoring force based on the radiation diffraction effect of the dual wind turbine floating wind power equipment platform, and combine the total load vector F of the wind turbine on the platform 合 、M 合 , establish the platform motion equation, and calculate the displacement D, velocity V and acceleration A of the floating wind power equipment platform with dual wind turbines at the next moment through the prediction-correction explicit time stepping method.

[0016] Step S6: The displacement D, velocity V and acceleration A vectors of the dual wind turbine floating wind power equipment platform are transmitted to the wind turbine structural dynamics solution module, and the real-time coordinates, velocity and acceleration of the blades of the two wind turbines are calculated according to the inclination angles of the two wind turbines.

[0017] Step S7: The floating wind power equipment platform with two wind turbines includes a unified control system. According to the current machine load, platform motion, wind speed and output power, the tower top speed, nacelle acceleration, tower base load, wind rotor speed, power generation power and electromagnetic torque of the two wind turbines are calculated and input into the control system. The blade pitch angles β1 and β2 and electromagnetic torque T of the two wind turbines are output according to the algorithm of the control system. q1 、T q2 .

[0018] Step S8: Based on the real-time coordinates, velocity and acceleration of the blades and the blade pitch angle output by the control system, the blade aerodynamic load is repeatedly calculated, and then the structural deformation of the blades and the structural deformation of the tower are solved until the time domain simulation calculation of the whole machine load of the dual wind turbine floating wind power equipment is completed.

[0019] Furthermore, in step S1, the design parameters used for calculating the aerodynamic load of the blade include the chord length, the twist angle and the airfoil lift and drag coefficient at different radii of the blade.

[0020] The design parameters required for the calculation of the platform's hydrodynamic loads include the platform's first-order wave force, radiation damping and additional mass parameters under waves of different frequencies, as well as the platform's hydrostatic stiffness matrix.

[0021] The design parameters required for the calculation of tower structure deformation and blade structure deformation include the modal vibration shapes of each mode of the blade and tower and the corresponding damping ratio, the cross-sectional mass, flapping stiffness and shimmy stiffness at different radii of the blade, and the cross-sectional mass, flapping stiffness and shimmy stiffness at different heights of the tower;

[0022] The design parameters required for system control mainly include rated power, rated speed, pitch angle change gain and generator electromagnetic torque gain parameters.

[0023] Furthermore, the wind field environment in step S2 is the time-varying data of the three directional components of wind speed in the plane covering the rotors and towers of the two wind turbines, and the wind field is turbulent wind, steady wind or other wind types that satisfy the wind shear law.

[0024] To calculate the aerodynamic loads of the two wind turbines separately, the aerodynamic force of each wind turbine must be calculated first. The detailed calculation process is as follows:

[0025] The aerodynamic force acting on the blade and the node corresponding to the blade are regarded as the generalized main force.

[0026] Calculate the generalized elastic forces of blades and towers, consider the gravity of structures such as blades, towers, nacelles and transmission systems, solve the motion equations of the entire wind turbine, obtain the acceleration of each structure, and calculate the loads at different sections of the tower structure.

[0027] Through the above process, the load vectors F1, M1 and F2, M2 of the two wind turbines in the local coordinate system at the tower base are obtained respectively; each vector includes three elements, which respectively represent the loads in the x, y and z directions in the space coordinate system.

[0028] Furthermore, in step S3, load transformation matrices T1 and T2 of two wind turbines are obtained, and the load transformation matrices are respectively:

[0029]

[0030] Where θ1, θ2 and θ3 are the roll, pitch and yaw of the platform respectively.

[0031] Furthermore, in step S4, the specific method of transforming the load vectors of the tower bases of the two wind turbines from the local coordinate system to the global coordinate system and transferring the load action point from the tower base to the intersection of the still water surface and the platform central axis is:

[0032]

[0033] Where, T1 -1 and are the inverse matrices of the load transformation matrices T1 and T2 respectively, and L1 and L2 are the position vectors from the tower base position of wind turbine model 1 and wind turbine model 2 to the intersection of the still water surface and the central axis of the platform respectively.

[0034] Furthermore, the platform motion equation at time t in step S5 is:

[0035]

[0036] Where m is the platform mass and the additional mass matrix corresponding to the wave frequency; c is the viscosity correction damping matrix; k is the platform hydrostatic stiffness matrix, h(t) is the acceleration pulse function matrix at time t, and the platform radiation damping force is calculated in the form of convolution; F 水 (t) is the hydrodynamic force on the platform, including the effects of waves and currents; F 系泊 (t) is the mooring restoring force; F 风电机组 (t) is the total load of the two wind turbines on the platform; the right side of the equation is a 1×6 vector, F 风电机组 (t) includes F 合 、M 合 ;

[0037] Where h(t) is expressed as:

[0038]

[0039] Where B is the radiation damping of the platform under the action of waves with a frequency of ω.

[0040] Furthermore, taking the wind direction as the perspective, the left wind turbine is model 1, and the right wind turbine is model 2. When the platform displacement, velocity and acceleration vectors are transmitted to the wind turbine structure dynamics solution part in step S6, the roll of wind turbine model 1 needs to be subtracted from its tilt angle α1, and the roll of wind turbine model 2 needs to be added with its tilt angle α2.

[0041] Furthermore, in step S8, a fourth-order Adams-Bashforth-Moulton prediction-correction time integration method is used, and the structural dynamics of the blades and towers of the two wind turbines are solved once in the prediction step and the correction step.

[0042] Compared with the prior art, the present invention has the following advantages:

[0043] The present invention can accurately calculate the nonlinear structural dynamic response of this type of novel wind energy conversion system under the action of wind, wave and flow loads while taking into account the complex interactions among the floating platform, the mooring system and the wind turbine.

[0044] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 The specific steps of a method for simulating and calculating the load of a floating wind power equipment with parallel dual wind turbines are shown;

[0047] Figure 2 The structure diagram of the floating wind power equipment with parallel dual wind turbines is shown;

[0048] Among them: 1 is wind turbine model 1; 2 is wind turbine model 2; 3 is calm water surface; 4 is floating platform; 5 is tension leg mooring system; 6 is platform center of gravity;

[0049] Figure 3 (a) shows a schematic diagram of the calculation results of the platform motion of a 5MW+5MW dual wind turbine floating wind turbine using a method for simulating the whole machine load of a parallel dual wind turbine floating wind turbine;

[0050] Figure 3 (b) shows a schematic diagram of the calculation results of the platform motion of a 5MW+5MW dual wind turbine floating wind turbine equipment using a CFD method for the whole machine load of a parallel dual wind turbine floating wind turbine equipment;

[0051] Figure 4 A schematic diagram showing a method for simulating the load of a parallel dual wind turbine floating wind power equipment and the time consumption of the CFD calculation method is shown;

[0052] Figure 5 (a) shows a comparison of the rotor speeds of a parallel dual wind turbine floating wind power equipment with two wind turbines controlled in different states under turbulent wind conditions;

[0053] Figure 5 (b) shows a comparison diagram of the pitch angles of the parallel dual wind turbine floating wind power equipment with two wind turbines controlled in different states under turbulent wind conditions;

[0054] Figure 6 (a) shows a comparison of the rotor power of a parallel dual wind turbine floating wind power equipment with two wind turbines controlled in different states under turbulent wind conditions;

[0055] Figure 6 (b) shows a comparison of the front and rear displacements of the tower top of a floating wind power equipment with two wind turbines in parallel with different control states under turbulent wind conditions;

[0056] Figure 6 (c) shows a comparison diagram of the outboard bending moment of the tower base of a parallel dual wind turbine floating wind power equipment with two wind turbines controlled in different states under turbulent wind conditions;

[0057] Figure 7 (a) shows a schematic diagram of the platform pitch change of the floating wind power equipment of the wind turbine control variable pitch variable speed dual wind turbine under turbulent wind conditions;

[0058] Figure 7 (b) shows a schematic diagram of the platform longitudinal fluctuation changes of the floating wind power equipment of the wind turbine control variable pitch variable speed dual wind turbine under turbulent wind conditions. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] The currently available technologies or software make it difficult to evaluate the load level, motion performance and power generation efficiency of dual-unit floating wind power equipment, which greatly limits the development of new floating wind power systems.

[0061] Although the prior art discloses some external design solutions and some simple control methods for parallel twin-rotor wind turbines, it does not mention how to calculate the complete machine load of the wind energy equipment of the parallel twin-rotor wind turbines.

[0062] The present invention can accurately calculate the nonlinear structural dynamic response of this type of novel wind energy conversion system under the action of wind, wave and flow loads while taking into account the complex interactions among the floating platform, the mooring system and the wind turbine.

[0063] like Figure 1-Figure 2 As shown, the present invention discloses a method for simulating and calculating the whole machine load of a parallel dual wind turbine floating wind power equipment, the method comprising:

[0064] Step S1: The aerodynamic loads of blades of the floating wind power equipment with dual wind turbines, the hydrodynamic loads of the platform, the deformation of the tower structure and the deformation of the blade structure, as well as the design parameters required for system control are given.

[0065] Step S2: define the wind farm environment, calculate the aerodynamic loads of the two wind turbines, and calculate the tower load vectors F1, M1 and F2, M2 of the two wind turbines at the tower base according to the structural deformation of the tower.

[0066] Step S3: Based on the roll θ1, pitch θ2 and bow pitch θ3 of the floating wind power equipment platform with two wind turbines at the current moment, and the inclination angles α1 and α2 of the two wind turbines, the load transformation matrices T1 and T2 of the two wind turbines are constructed.

[0067] Step S4: transform the tower load vectors of the two wind turbines from the local coordinate system to the global coordinate system, and transfer the load action point from the tower base to the intersection of the still water surface and the central axis of the platform, and add the transformed loads to obtain the total load vector F of the two wind turbines on the platform 合 、M 合 .

[0068] Step S5: Calculate the platform hydrodynamic load and mooring restoring force based on the radiation diffraction effect of the dual wind turbine floating wind power equipment platform, and combine the total load vector F of the wind turbine on the platform 合 、M 合 , establish the platform motion equation, and calculate the displacement D, velocity V and acceleration A of the floating wind power equipment platform with dual wind turbines at the next moment through the prediction-correction explicit time stepping method.

[0069] Step S6: The displacement D, velocity V and acceleration A vectors of the dual wind turbine floating wind power equipment platform are transmitted to the wind turbine structural dynamics solution module, and the real-time coordinates, velocity and acceleration of the blades of the two wind turbines are calculated according to the inclination angles of the two wind turbines.

[0070] Step S7: The floating wind power equipment platform with two wind turbines includes a unified control system. According to the current machine load, platform motion, wind speed and output power, the tower top speed, nacelle acceleration, tower base load, wind rotor speed, power generation power and electromagnetic torque of the two wind turbines are calculated and input into the control system. The blade pitch angles β1 and β2 and electromagnetic torque T of the two wind turbines are output according to the algorithm of the control system. q1 、T q2 .

[0071] Step S8: Based on the real-time coordinates, velocity and acceleration of the blades and the blade pitch angle output by the control system, the blade aerodynamic load is repeatedly calculated, and then the structural deformation of the blades and the structural deformation of the tower are solved until the time domain simulation calculation of the whole machine load of the dual wind turbine floating wind power equipment is completed.

[0072] Furthermore, the dual wind turbine floating wind power equipment described in step S1 includes a floating platform, a single-point mooring system, and two wind turbines. Among them, the floating platform 4 has a central column, and the top of the column is higher than the still water surface 3 by a certain distance, generally not less than twice the significant wave height in extreme marine environments. The cable guide hole position of the tension leg mooring system 5 is connected below the center of gravity 6 of the platform, and a tensioned tendon design scheme is adopted. The connection position between the tension leg mooring system 5 and the floating platform 4 can rotate freely within a range of 360 degrees to realize the free facing of the floating platform 4 to the wind. Two completely identical wind turbines are placed side by side and symmetrically on the central column of the floating platform 4, with opposite rotation directions. The two wind turbines have the same angle with the central axis of the platform, and the hub spacing of the two wind turbines after tilting is not less than 1.2 times the diameter of the wind rotor.

[0073] Furthermore, in step S1, the design parameters used for calculating the aerodynamic load of the blade include the chord length, the twist angle and the airfoil lift and drag coefficient at different radii of the blade.

[0074] The design parameters required for the calculation of the platform's hydrodynamic loads include the platform's first-order wave force, radiation damping and additional mass parameters under waves of different frequencies, as well as the platform's hydrostatic stiffness matrix.

[0075] The design parameters required for the calculation of tower structure deformation and blade structure deformation include the modal vibration shapes of each mode of the blade and tower and the corresponding damping ratio, the cross-sectional mass, flapping stiffness and shimmy stiffness at different radii of the blade, and the cross-sectional mass, flapping stiffness and shimmy stiffness at different heights of the tower;

[0076] The design parameters required for system control mainly include rated power, rated speed, pitch angle change gain and generator electromagnetic torque gain parameters.

[0077] Furthermore, the wind field environment in step S2 is the time-varying data of the three directional components of wind speed in the plane covering the rotors and towers of the two wind turbines, and the wind field is turbulent wind, steady wind or other wind types that satisfy the wind shear law.

[0078] The aerodynamic loads of the two wind turbines are calculated by the generalized dynamic inflow method and blade element momentum theory. The aerodynamic force of each wind turbine must be calculated first. The detailed calculation process is as follows:

[0079] (1) According to the defined wind field environment data, the real-time inflow velocity at each cross section of the wind rotor blade is obtained as the boundary condition to solve the velocity potential flow equation of the wind rotor plane based on the generalized dynamic inflow method to obtain the induced velocity of the wind rotor plane;

[0080] (2) According to the rotor speed and induction, determine the velocity triangle at each section of the blade and calculate the actual angle of attack of the section;

[0081] (3) based on the airfoil lift and drag coefficients provided in step S1, the lift coefficient and drag coefficient at the corresponding angle of attack are retrieved, and the aerodynamic force of the blade section is calculated by blade element theory;

[0082] (4) Superimpose the aerodynamic forces of each blade section to obtain the aerodynamic force of the entire wind wheel.

[0083] The aerodynamic force acting on the blade and the node corresponding to the blade are regarded as the generalized main force.

[0084] Calculate the generalized elastic forces of blades and towers, consider the gravity of structures such as blades, towers, nacelles and transmission systems, solve the motion equations of the entire wind turbine, obtain the acceleration of each structure, and calculate the loads at different sections of the tower structure.

[0085] Through the above process, the load vectors F1, M1 and F2, M2 of the two wind turbines in the local coordinate system at the tower base are obtained respectively; each vector includes three elements, which respectively represent the loads in the x, y and z directions in the space coordinate system.

[0086] Furthermore, in step S3, load transformation matrices T1 and T2 of two wind turbines are obtained, and the load transformation matrices are respectively:

[0087]

[0088] Where θ1, θ2 and θ3 are the roll, pitch and yaw of the platform respectively.

[0089] Furthermore, in step S4, the specific method of transforming the load vectors of the tower bases of the two wind turbines from the local coordinate system to the global coordinate system and transferring the load action point from the tower base to the intersection of the still water surface and the platform central axis is:

[0090]

[0091] Where, T1 -1 and are the inverse matrices of the load transformation matrices T1 and T2 respectively, and L1 and L2 are the position vectors from the tower base position of wind turbine model 1 and wind turbine model 2 to the intersection of the still water surface and the central axis of the platform respectively.

[0092] Furthermore, the platform motion equation at time t in step S5 is:

[0093]

[0094] Where m is the platform mass and the additional mass matrix corresponding to the wave frequency; c is the viscosity correction damping matrix; k is the platform hydrostatic stiffness matrix, h(t) is the acceleration pulse function matrix at time t, and the platform radiation damping force is calculated in the form of convolution; F 水 (t) is the hydrodynamic force on the platform, including the effects of waves and currents; F 系泊 (t) is the mooring restoring force; F 风电机组 (t) is the total load of the two wind turbines on the platform; the right side of the equation is a 1×6 vector, F 风电机组 (t) includes F 合 、M 合 ;

[0095] Where h(t) is expressed as:

[0096]

[0097] Where B is the radiation damping of the platform under the action of waves with a frequency of ω. The explicit time stepping method for solving the platform motion equations can be Newton-Rapson, Newmark-β, Generalized-α, fourth-order Runge-Kutta or fourth-order Adams-Bashforth-Moulton method.

[0098] Furthermore, taking the wind direction as the perspective, the left wind turbine is model 1, and the right wind turbine is model 2. When the platform displacement, velocity and acceleration vectors are transmitted to the wind turbine structure dynamics solution part in step S6, the roll of wind turbine model 1 needs to be subtracted from its tilt angle α1, and the roll of wind turbine model 2 needs to be added with its tilt angle α2.

[0099] Furthermore, the control instructions for the blade pitch angles and the generator electromagnetic torques of the two wind turbines in step S7 are calculated based on the state space of the entire floating wind turbine equipment. Among them, the control closed loop of wind turbine model 1 considers the rotor thrust, tower vibration velocity, cabin vibration acceleration, generator power and tower base load of wind turbine model 2, and the control closed loop of wind turbine model 2 also considers the relevant response parameters of wind turbine model 1, and the control closed loops of both consider the motion state of the platform, including displacement, velocity and acceleration.

[0100] Furthermore, in step S8, a fourth-order Adams-Bashforth-Moulton prediction-correction time integration method is used, and the structural dynamics of the blades and towers of the two wind turbines are solved once in the prediction step and the correction step.

[0101] Verification Example

[0102] Verification Example 1, such as Figure 3-Figure 4 As shown, in order to verify that the calculation method proposed in the present invention can take into account the full coupling effect of the parallel twin wind turbine floating wind power equipment, including the coupling effect of the two wind turbines with the platform and mooring, as well as the aerodynamic-hydrodynamic-servo-elastic coupling effect of the whole machine, two NREL 5MW wind turbines are installed on the OOStar floating platform to form a 10MW parallel twin wind turbine floating wind power equipment. First, the platform's sway and pitch under different wind speeds calculated by this method are compared with the traditional CFD method. The results are shown in Figure 1. Figure 2 As shown in the figure, the calculation time of the two methods is compared, and the results are as follows Figure 3 As shown, it can be found that the results obtained by the two calculation methods are very consistent, indicating that this method can effectively consider the interaction between the two wind turbines and the coupling effect with the platform and mooring system, and this method has higher calculation efficiency, which is more than 800 times that of the CFD method.

[0103] Verification Example 2, such as Figure 5-Figure 7As shown in the figure, the dynamic response of the parallel dual wind turbine floating wind power equipment composed of two NREL 5MW wind turbines and OOStar10MW wind power platform is given when the control strategies of the two wind turbines are different, and the platform six-degree-of-freedom motion and mooring tension results are given. The control strategies of the two wind turbines are different. Wind turbine model 1 is a constant speed and fixed pitch control strategy, while wind turbine model 2 is a variable pitch and variable speed control strategy. As can be seen from the figure, the rotor speed and pitch angle of wind turbine model 2 are both dynamically changing, which is significantly different from wind turbine model 1. The rotor power of the two wind turbines is slightly different, but due to different control strategies, the output power is different. The responses of the tower top front and rear displacement, tower base out-of-plane bending moment and other responses of the two wind turbines are also different, indicating that this method can calculate the dynamic response of two wind turbines placed on the same platform. The results of platform sway and pitch are also reasonable, which is larger than when a single wind turbine acts.

[0104] In summary, the present invention, based on the accurate calculation of the whole machine load of the floating wind power equipment with dual wind turbines, improves the calculation speed by more than 800 times compared with the CFD method, and can also accurately calculate the whole machine dynamic response of the floating wind power equipment with parallel dual wind turbines under different control strategies. The present invention lays a foundation for the large-scale promotion of floating wind power equipment with parallel dual wind turbines.

Claims

1. A method for simulating and calculating the load of a floating wind power equipment with parallel dual wind turbines, characterized in that: include: Step S1: providing blade aerodynamic loads, platform hydrodynamic loads, tower structure deformations and blade structure deformations of a dual wind turbine floating wind power equipment, as well as design parameters required for system control; Step S2: define the wind farm environment, calculate the aerodynamic loads of the two wind turbines, and calculate the tower load vectors F1, M1 and F2, M2 of the two wind turbines at the tower base according to the structural deformation of the tower; Step S3: constructing load transformation matrices T1 and T2 of the two wind turbines based on the roll θ1, pitch θ2 and bow θ3 of the floating wind power equipment platform with two wind turbines at the current moment, and the inclination angles α1 and α2 of the two wind turbines; Step S4: transform the tower load vectors of the two wind turbines from the local coordinate system to the global coordinate system, and transfer the load action point from the tower base to the intersection of the still water surface and the central axis of the platform, and add the transformed loads to obtain the total load vector F of the two wind turbines on the platform 合 、M 合 ; Step S5: Calculate the platform hydrodynamic load and mooring restoring force based on the radiation diffraction effect of the dual wind turbine floating wind power equipment platform, and combine the total load vector F of the wind turbine on the platform 合 、M 合 , establish the platform motion equation, and calculate the displacement D, velocity V and acceleration A of the floating wind power equipment platform with dual wind turbines at the next moment through the prediction-correction explicit time stepping method; Step S6: The displacement D, velocity V and acceleration A vectors of the dual wind turbine floating wind power equipment platform are transmitted to the wind turbine structural dynamics solution module, and the real-time coordinates, velocity and acceleration of the blades of the two wind turbines are calculated according to the inclination angles of the two wind turbines; Step S7: The floating wind power equipment platform with two wind turbines includes a unified control system. According to the current machine load, platform motion, wind speed and output power, the tower top speed, nacelle acceleration, tower base load, wind rotor speed, power generation power and electromagnetic torque of the two wind turbines are calculated and input into the control system. The blade pitch angles β1 and β2 and electromagnetic torque T of the two wind turbines are output according to the algorithm of the control system. q1 、T q2 ; Step S8: Based on the real-time coordinates, velocity and acceleration of the blades and the blade pitch angle output by the control system, the blade aerodynamic load is repeatedly calculated, and then the structural deformation of the blades and the structural deformation of the tower are solved until the time domain simulation calculation of the whole machine load of the dual wind turbine floating wind power equipment is completed.

2. The method according to claim 1, characterized in that In step S1, the design parameters used for calculating the aerodynamic load of the blade include the chord length, twist angle and airfoil lift and drag coefficient at different radii of the blade; The design parameters required for the calculation of the platform's hydrodynamic loads include the platform's first-order wave force, radiation damping and additional mass parameters under waves of different frequencies, as well as the platform's hydrostatic stiffness matrix; The design parameters required for the calculation of tower structure deformation and blade structure deformation include the modal vibration shapes of each mode of the blade and tower and the corresponding damping ratio, the cross-sectional mass, flapping stiffness and shimmy stiffness at different radii of the blade, and the cross-sectional mass, flapping stiffness and shimmy stiffness at different heights of the tower; The design parameters required for system control mainly include rated power, rated speed, pitch angle change gain and generator electromagnetic torque gain parameters.

3. The method according to claim 1, characterized in that: The wind field environment in step S2 is the time-varying data of the three directional components of the wind speed in the plane covering the wind rotors and towers of the two wind turbines, and the wind field is turbulent wind or steady wind; To calculate the aerodynamic loads of the two wind turbines separately, the aerodynamic force of each wind turbine must be calculated first. The detailed calculation process is as follows: The aerodynamic force of the blade and the node corresponding to the blade are regarded as the generalized main force; Calculate the generalized elastic force of blades and tower, consider the gravity of structures such as blades, tower, nacelle and transmission system, solve the motion equation of the entire wind turbine, obtain the acceleration of each structure, and calculate the load at different sections of the tower structure; The tower load vectors F1, M1 and F2, M2 of the two wind turbines in the local coordinate system at the tower base are obtained through the above process; each vector includes three elements, which respectively represent the loads in the x, y and z directions in the space coordinate system.

4. The method according to claim 1, characterized in that: In step S3, the load transformation matrices T1 and T2 of the two wind turbines are obtained. The load transformation matrices are: Where θ1, θ2 and θ3 are the roll, pitch and yaw of the platform respectively.

5. The method according to claim 1, characterized in that The specific method of transforming the load vectors of the towers of the two wind turbines from the local coordinate system to the global coordinate system and transferring the load action point from the tower base to the intersection of the still water surface and the central axis of the platform in step S4 is: In the formula, and are the inverse matrices of the load transformation matrices T1 and T2, respectively. Taking the wind direction as the perspective, the wind turbine on the left is model 1, and the wind turbine on the right is model 2. L1 and L2 are the position vectors from the tower base position of wind turbine model 1 and wind turbine model 2 to the intersection of the still water surface and the central axis of the platform, respectively.

6. The method according to claim 1, characterized in that In step S5, the platform motion equation is: Where t is any time when the floating wind power equipment platform with two wind turbines is working, m is the platform mass and the additional mass matrix corresponding to the wave frequency; c is the viscosity correction damping matrix; k is the platform hydrostatic stiffness matrix, h(t) is the acceleration pulse function matrix at time t, and the platform radiation damping force is calculated in the form of convolution; F 水 (t) is the hydrodynamic force on the platform, including the effects of waves and currents; F 系泊 (t) is the mooring restoring force; F 风电机组 (t) is the total load of the two wind turbines on the platform; the right side of the equation is a 1×6 vector, F 风电机组 (t) includes F 合 、M 合 ; Where h(t) is expressed as: Where ω is the operating frequency, and B is the radiation damping of the platform under the action of waves with a frequency of ω.

7. The method according to claim 5, characterized in that When the displacement D, velocity V and acceleration A vectors of the dual wind turbine floating wind power equipment platform are transmitted to the wind turbine structural dynamics solution module in step S6, the roll of wind turbine model 1 needs to be subtracted from its tilt angle α1, while the roll of wind turbine model 2 needs to be added with its tilt angle α2.

8. The method according to claim 1, characterized in that In step S8, the fourth-order Adams-Bashforth-Moulton prediction-correction time integration method is used, and the structural dynamics of the blades and towers of the two wind turbines are solved once in the prediction step and the correction step.

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