Test method for multi-rotor thrust collaborative simulation of aerodynamic load of floating vertical axis fan
By optimizing the rotor thrust distribution through a tic-tac-toe rotor array and the quadratic programming method, accurate simulation of the six-degree-of-freedom aerodynamic loads of a floating vertical-axis wind turbine was achieved, solving the simulation difficulties under the Reynolds scale effect and improving the accuracy and stability of the simulation results.
Patent Information
- Application Number
- CN202510822337.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-19
- Publication Date
- 2025-09-12
AI Technical Summary
There is no test method in the prior art that can simultaneously simulate the aerodynamic loads of six degrees of freedom of a floating vertical axis wind turbine. In particular, under the Reynolds scale effect, it is difficult to accurately simulate the aerodynamic loads of multiple degrees of freedom.
An experimental method was designed to simulate the aerodynamic loads of a floating vertical-axis wind turbine using the coordinated thrust of multiple rotors. A geometrically symmetrical layout structure of a tic-tac-toe rotor array was adopted. A six-component force sensor was used to measure the aerodynamic loads at the bottom of the tower in real time. The thrust distribution of the rotor device was optimized using the quadratic programming method to achieve synchronous and precise reproduction of the aerodynamic loads in six degrees of freedom.
It achieves accurate simulation of the six-degree-of-freedom aerodynamic loads at the base of a floating vertical-axis wind turbine tower, avoids load tracking distortion caused by motor inertia delay, improves the accuracy and stability of simulation results, ensures instantaneous fluctuation simulation under turbulent wind conditions, and has fault tolerance capabilities.
Smart Images
Figure CN120628531A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of wind power generation technology, and in particular to a test method for simulating the aerodynamic load of a floating vertical axis wind turbine by coordinating the thrust of multiple rotors. Background Art
[0002] Floating vertical-axis wind turbines (VAWTs) have become a research hotspot for deep-sea wind power development due to their multidirectional wind exposure, simple structure, and ease of scaling. Tank testing of VAWTs is essential for promoting their development. Tank testing of VAWTs focuses on the hydrodynamics of the floating foundation and mooring system. Accurate simulation of the aerodynamic loads of VAWTs, a key external excitation force, is crucial for ensuring the accuracy of hydrodynamic analysis results for the floating foundation and mooring system.
[0003] Tank tests for floating vertical-axis wind turbines are typically designed based on the Froude criterion. However, under Froude's similarity law, the Reynolds number can drop by several orders of magnitude, significantly reducing the aerodynamic load on the floating vertical-axis wind turbine compared to the theoretical value. This phenomenon is known as the Reynolds scaling effect. Existing technologies address the reduced aerodynamic load caused by the Reynolds scaling effect by increasing wind speed, adding thrust compensation mechanisms, or employing rotors with similar aerodynamic performance. However, these approaches are primarily targeted at horizontal-axis wind turbines.
[0004] Because floating vertical-axis wind turbines generate periodic, multi-degree-of-freedom aerodynamic loads during rotation, the Reynolds scaling effect poses a major challenge in simulating these loads in tank tests. Currently, no existing test method can simultaneously simulate the aerodynamic loads of floating vertical-axis wind turbines in all six degrees of freedom. Summary of the Invention
[0005] In response to the above-mentioned problems and technical requirements, this application proposes a test method for simulating the aerodynamic load of a floating vertical axis wind turbine using multi-rotor thrust coordination. The technical solution of this application is as follows:
[0006] A test method for simulating aerodynamic loads of a floating vertical axis wind turbine using multi-rotor thrust coordination includes the following steps:
[0007] Calculate the real-scale aerodynamic load of the floating vertical axis wind turbine at the tower bottom at each simulation time under the target operating conditions, and reduce the real-scale aerodynamic load to the model scale according to the scale ratio λ to obtain the model aerodynamic load at each simulation time;
[0008] An aerodynamic load simulation device is manufactured. The aerodynamic load simulation device includes a six-component force sensor installed at the bottom of a tower, a tower frame fixedly connected to the six-component force sensor, and multiple support rods of the same specifications fixed to the tower frame. A rotor device is provided at each end of each support rod, and the rotation plane of the rotor device is perpendicular to the support rod.
[0009] For any simulation time t, the constraints of the aerodynamic load simulation are determined based on the thrust generated by each rotor assembly meeting the requirements of the model aerodynamic load at the simulation time t;
[0010] The objective function of the aerodynamic load simulation is determined based on the thrust smoothness of each rotor device at the simulation time t and the thrust balance of all rotor devices at the simulation time t. The smaller the objective function, the higher the thrust smoothness of each rotor device and the higher the thrust balance of all rotor devices.
[0011] Based on the constraints, the quadratic programming method is used to solve the candidate thrust generated by each rotor device when the objective function is minimized.
[0012] An aerodynamic load simulation device is placed in a test water tank to control the rotation of each rotor device to generate candidate thrust. A six-component force sensor is used to measure the actual aerodynamic load generated by the aerodynamic load simulation device at the bottom of the tower, and the simulation error between the actual aerodynamic load and the model aerodynamic load is calculated. The thrust generated by each rotor device is corrected according to the simulation error until the simulation error is no greater than the error threshold, thereby obtaining the aerodynamic load of the floating vertical axis wind turbine at the simulation time t.
[0013] A further technical solution is that the aerodynamic load simulation device includes a crisscross support frame, a height adjustment device is provided at the center of the crisscross support frame and is fixed to the tower through the height adjustment device; the crisscross support frame includes two groups of support rods arranged vertically, each group of support rods includes two mutually parallel support rods, and the spacing between the support rods in each group is d; one group of support rods is arranged in the x-axis direction of the body coordinate system of the aerodynamic load simulation device, and the other group of support rods is arranged in the y-axis direction of the body coordinate system of the aerodynamic load simulation device, the origin of the body coordinate system of the aerodynamic load simulation device is located on the tower, and the two rotor devices on the same side of each group of support rods rotate in opposite directions;
[0014] The aerodynamic load simulation device also includes a counterweight device, which includes two vertically arranged counterweight struts of the same specifications, with counterweight blocks arranged at both ends of each counterweight strut, one counterweight strut is arranged along the x-axis direction of the body coordinate system of the aerodynamic load simulation device, and the other counterweight strut is arranged along the y-axis direction of the body coordinate system of the aerodynamic load simulation device; the weight of each counterweight block is determined according to the scale ratio λ based on the actual scale weight of the floating vertical axis wind turbine, the height of the counterweight device is determined according to the scale ratio λ based on the actual scale center of gravity height of the floating vertical axis wind turbine, and the length of each counterweight strut is determined according to the scale ratio λ based on the actual scale inertia of the floating vertical axis wind turbine.
[0015] A further technical solution is that, for any simulation time t, the model aerodynamic load includes the model thrust F along the x-axis direction of the body coordinate system of the aerodynamic load simulation device. Xm (t) and the model bending moment M around the x-axis of the body coordinate system of the aerodynamic load simulation device Xm (t); Determine the fixed height of the height adjustment device under the target working condition
[0016] A further technical solution is that the model aerodynamic load also includes a model thrust F along the y-axis direction of the body coordinate system of the aerodynamic load simulation device. Ym (t) and the model torque M rotating around the z-axis of the body coordinate system of the aerodynamic load simulation device Zm (t); The thrust generated by the rotor device in the x-axis direction of the body coordinate system of the aerodynamic load simulation device is used to simulate the model thrust F in the x-axis direction Xm (t) and the model torque M around the z-axis Zm (t); The thrust generated by the rotor device in the y-axis direction of the body coordinate system of the aerodynamic load simulation device is used to simulate the model thrust F in the y-axis direction Ym (t); The constraints for aerodynamic load simulation are determined as follows:
[0017]
[0018] Among them, F1(t) and F2(t) are the thrusts generated by the rotor devices at the starting end points of the two support rods arranged in the x-axis direction of the body coordinate system of the aerodynamic load simulation device, F3(t) and F4(t) are the thrusts generated by the rotor devices at the ending end points of the two support rods arranged in the x-axis direction of the body coordinate system of the aerodynamic load simulation device, F5(t) and F6(t) are the thrusts generated by the rotor devices at the ending end points of the two support rods arranged in the y-axis direction of the body coordinate system of the aerodynamic load simulation device, and F7(t) and F8(t) are the thrusts generated by the rotor devices at the starting end points of the two support rods arranged in the y-axis direction of the body coordinate system of the aerodynamic load simulation device; for the thrust F generated by any rotor device i i (t)≥0.
[0019] A further technical solution is to calculate the thrust smoothness f of any rotor device i at any simulation time t. i (t), and the thrust balance degree g(t) of all rotor devices at any simulation time t, determine the objective function of aerodynamic load simulation T is the simulation duration, α is the thrust distribution weight, t is an integer parameter with 1≤t≤T, and i is an integer parameter with 1≤i≤8.
[0020] A further technical solution is to generate the thrust F of the rotor device i at the simulation time t. i (t) and the thrust F generated by the rotor device i at the simulation time t-1 i (t-1), determine the thrust smoothness f of rotor device i at simulation time t i (t)=(F i (t)-F i (t-1)) 2 .
[0021] A further technical solution is to determine the maximum thrust F generated by all rotor devices at the simulation time t max (t) and the minimum thrust F min (t), determine the thrust balance degree of all rotor devices at the simulation time t g(t) = (F max (t)-F min (t)) 2 .
[0022] A further technical solution is to correct the thrust generated by each rotor device according to the simulation error, including:
[0023] When the simulation error is greater than the error threshold, the thrust distribution weight α of the objective function J is adjusted, and the candidate thrust generated by each rotor device when the objective function is minimized is recalculated using the quadratic programming algorithm to obtain the corrected thrust generated by each rotor device.
[0024] A further technical solution is that the model aerodynamic load includes a model thrust F along the x-axis direction of the body coordinate system of the aerodynamic load simulation device. Xm (t), model thrust F along the y-axis direction of the body coordinate system of the aerodynamic load simulation device Ym (t) and the model torque M rotating around the z-axis of the body coordinate system of the aerodynamic load simulation device Zm (t); determine the simulation error e(t) between the measured aerodynamic load and the model aerodynamic load at the simulation time t:
[0025]
[0026] Among them, F′ Xm (t) is the measured thrust along the x-axis of the body coordinate system of the aerodynamic load simulation device, F′ Ym (t) is the measured thrust along the y-axis of the body coordinate system of the aerodynamic load simulation device, M′ Xm (t) is the measured value of the torque rotating around the z-axis of the body coordinate system of the aerodynamic load simulation device.
[0027] A further technical solution is that the real-scale aerodynamic load at any simulation time t includes the real-scale thrust F along the x-axis direction of the body coordinate system of the floating vertical axis wind turbine. X (t), the real-scale thrust F along the y-axis of the floating vertical axis wind turbine's body coordinate system Y (t), the real-scale torque M around the z-axis of the floating vertical axis wind turbine's body coordinate system Z (t) and the real-scale bending moment M around the x-axis of the floating vertical axis wind turbine's body coordinate system X (t); The model aerodynamic load at simulation time t includes the model thrust F along the x-axis direction of the body coordinate system of the aerodynamic load simulation device Xm (t), model thrust F along the y-axis direction of the body coordinate system of the aerodynamic load simulation device Ym (t), the model torque M rotating around the z-axis of the body coordinate system of the aerodynamic load simulation device Zm (t) and the model bending moment M around the x-axis of the body coordinate system of the aerodynamic load simulation device Xm (t);
[0028] Determine the model thrust according to the scale ratio λ Determine model thrust Determine the model torque Determine the model bending moment The scale ratio λ>1.
[0029] The beneficial technical effects of this application are:
[0030] This application proposes a test method for collaboratively simulating the aerodynamic loads of a floating vertical axis wind turbine using multi-rotor thrust. By designing an aerodynamic load simulation device with a geometrically symmetrical layout structure of a criss-cross rotor array to conduct a water tank test, the aerodynamic loads of the floating vertical axis wind turbine are simulated. This method breaks the limitation that traditional simulation devices can only simulate linear loads along and perpendicular to the wind direction but cannot simulate torque around the vertical axis, and realizes the synchronous and accurate reproduction of the six-degree-of-freedom aerodynamic loads at the tower base of the floating vertical axis wind turbine.
[0031] By limiting the rate of change of thrust of each rotor assembly at adjacent simulation moments and the thrust difference of all rotor assemblies at the same simulation moment, the optimal thrust combination of each rotor assembly is obtained by using a thrust smoothness and balance optimization algorithm, which can more accurately simulate the actual aerodynamic load. When the aerodynamic load to be simulated undergoes a step change, the present application uses an optimization algorithm to automatically select a smooth transition scheme for the thrust of multiple rotor assemblies, and compensates for the load change through the coordinated adjustment of each rotor assembly. This fundamentally avoids the problem of load tracking distortion caused by phase lag caused by motor inertia delay when the magnitude and direction of the aerodynamic load to be simulated suddenly changes with the existing rotating main shaft method. This ensures the accuracy of the simulation results while greatly shortening the response time. In particular, when simulating turbulent wind conditions, traditional methods can cause peak load loss due to phase lag, while the present application can successfully simulate the instantaneous fluctuations of aerodynamic load under various wind conditions. Moreover, the thrust balance constraint of all rotor assemblies forces each rotor assembly to have a uniform load, which can prevent a rotor assembly from being in a high-load state for a long time, effectively improving the performance and service life of each rotor assembly.
[0032] In addition, this application uses a six-component force sensor to measure the actual aerodynamic load at the tower base in real time to assess simulation errors. A closed-loop feedback mechanism dynamically adjusts the thrust distribution of each rotor assembly to continuously improve simulation accuracy. Furthermore, in the event of rotor assembly failure or extreme load fluctuations leading to local overload and system crash, this application can achieve fault tolerance and promptly distribute the load of the faulty rotor assembly to other functioning rotor assembly, ensuring the normal and stable conduct of the test.
[0033] Compared with the dual-rotor coupling control method of the prior art, the geometrically symmetrical layout structure of the present application ensures that each rotor device is controlled separately, thereby realizing multi-degree-of-freedom decoupling control of the floating vertical axis wind turbine, eliminating the additional inertial interference introduced by the rotating main shaft, ensuring the accuracy of the simulation results, and providing an accurate data basis for high-order motion coupling analysis. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Figure 1 It is a flow chart of the test method.
[0035] Figure 2 It is a structural diagram of the aerodynamic load simulation device.
[0036] Figure 3 This is the main view of the aerodynamic load simulation device.
[0037] Figure 4 This is a schematic diagram of the thrust distribution of each rotor device of the aerodynamic load simulation device.
[0038] Figure 5 FIG. 1 is a graph showing aerodynamic load history of a model according to an embodiment.
[0039] Figure 6 A time history graph of the thrust generated by each rotor assembly in one embodiment is shown.
[0040] Figure 7 FIG. 1 is a box plot of thrust statistics generated by each rotor assembly in an embodiment.
[0041] Reference numerals: 1. cross-shaped support frame, 2. height adjustment device, 3. rotor device, 4. counterweight device, 5. tower, 6. six-component force sensor, 7. floating foundation; 301. motor, 302. rotor, 401. counterweight block, 402. counterweight support rod. DETAILED DESCRIPTION
[0042] The specific implementation of this application will be further described below with reference to the accompanying drawings.
[0043] This application proposes a test method for simulating the aerodynamic load of a floating vertical axis wind turbine using multi-rotor thrust synergy. Please refer to Figure 1 The specific steps of the method are as follows:
[0044] Step 1: Calculate the real-scale aerodynamic load of the floating vertical axis wind turbine at the tower bottom at each simulation time under the target operating condition, and reduce the real-scale aerodynamic load to the model scale according to the scale ratio λ to obtain the model aerodynamic load at each simulation time.
[0045] The numerical software Qblade is used to calculate the real-scale aerodynamic load of the floating vertical axis wind turbine at the bottom of the tower under the target working conditions. The real-scale aerodynamic load includes the force and moment along the wind direction. Then, the real-scale aerodynamic load is decomposed into six degrees of freedom real-scale aerodynamic loads according to the body coordinate system of the floating vertical axis wind turbine. The real-scale aerodynamic load at any simulation time t includes the real-scale thrust F along the x-axis direction of the body coordinate system of the floating vertical axis wind turbine. X (t), the real-scale thrust F along the y-axis of the floating vertical axis wind turbine's body coordinate system Y (t), actual scale fan weight F Z (t) (i.e., the real-scale aerodynamic load along the z-axis of the floating vertical axis wind turbine's body coordinate system), the real-scale bending moment M rotating around the x-axis of the floating vertical axis wind turbine's body coordinate system X(t), the real-scale bending moment M around the y-axis of the floating vertical axis wind turbine's body coordinate system Y (t), the real-scale torque M around the z-axis of the floating vertical axis wind turbine's body coordinate system Z (t). The x-axis of the floating vertical axis wind turbine's body coordinate system runs along the length of the floating foundation and can be set to point from the tail to the bow. The y-axis of the floating vertical axis wind turbine's body coordinate system runs along the width of the floating foundation and can be set to point from the starboard side to the port side. The positive z-axis of the floating vertical axis wind turbine's body coordinate system points vertically upward along the tower of the floating vertical axis wind turbine. To verify that the aerodynamic load simulation device of this application can simulate aerodynamic loads with a wide range of fluctuations, the wind conditions in the target operating conditions of this application are selected to be more consistent with the turbulent wind in a real sea environment, with a turbulence degree of 16.4%.
[0046] The scale ratio λ is determined based on the actual scale size and weight of the floating vertical axis wind turbine to be simulated and the size of the experimental water tank. The actual scale aerodynamic load is reduced to the model scale according to the scale ratio λ to obtain the model aerodynamic load at each simulation time. The model aerodynamic load at simulation time t includes the model thrust F along the x-axis direction of the body coordinate system of the aerodynamic load simulation device. Xm (t), model thrust F along the y-axis direction of the body coordinate system of the aerodynamic load simulation device Ym (t), model weight F Zm (t) (i.e., the model aerodynamic load along the z-axis of the body coordinate system of the aerodynamic load simulation device), the model bending moment M rotating around the x-axis of the body coordinate system of the aerodynamic load simulation device Xm (t), the model bending moment M around the y-axis of the body coordinate system of the aerodynamic load simulation device Ym (t) and the model torque M rotating around the z-axis of the body coordinate system of the aerodynamic load simulation device Zm (t).
[0047] In one embodiment, the model thrust is determined according to the scale ratio λ Determine model thrust Determine the model weight Determine the model torque Determine the model bending moment Determine the model bending moment The scale ratio λ>1. It should be noted that in order to accurately simulate the six-degree-of-freedom aerodynamic load of the floating vertical axis wind turbine, the body coordinate system of the aerodynamic load simulation device is set according to the body coordinate system of the floating vertical axis wind turbine. The coordinate axis direction of the body coordinate system of the aerodynamic load simulation device is the same as the coordinate axis direction of the body coordinate system of the floating vertical axis wind turbine. For the coordinate axis of the body coordinate system of the aerodynamic load simulation device, please refer to Figure 4 The direction of the thrust in the model.
[0048] In one embodiment, the model thrust F in the x-axis direction Xm (t), model thrust F in the y-axis direction Ym (t) and model torque M Zm (t) as an example, the model thrust F at each simulation moment under the target working condition is calculated Xm (t), F Ym (t) and model torque M Zm The time history curve of (t) is as follows Figure 5 As shown. Figure 5 It can be seen that the aerodynamic load will fluctuate significantly around a mean value within each rotation cycle of the floating vertical axis wind turbine. The frequency of the fluctuation is converted to: the real-scale fluctuation frequency is about 28.8 rpm, the real-scale wind speed is 9.6 rpm, and the real-scale fluctuation frequency is three times the real-scale wind speed, that is, the 3P frequency, which corresponds to the model scale is also the 3P frequency.
[0049] Step 2: Make an aerodynamic load simulation device. The aerodynamic load simulation device includes a six-component force sensor installed at the bottom of the tower, a tower fixedly connected to the six-component force sensor, and multiple support rods of the same specifications fixed to the tower. A rotor device is provided at the end points of each support rod, and the rotation plane of the rotor device is perpendicular to the support rod.
[0050] An aerodynamic load simulation device is manufactured according to the scale ratio λ and in combination with the principle of aerodynamic load action during the operation of a floating vertical axis wind turbine. Since the actual operating conditions of a floating vertical axis wind turbine are complex and changeable, the natural wind field is highly turbulent, including vortices ranging from large scale (kilometer level) to small scale (centimeter level). These vortices cause violent random fluctuations in wind speed and wind direction in space and time. This makes it extremely difficult to manufacture a test wind field in a conventional water tank test. In order to avoid manufacturing a test wind field in a water tank test, the present application takes into account that the aerodynamic load during the operation of a floating vertical axis wind turbine can be obtained by synthetic simulation of aerodynamic loads with six degrees of freedom. Therefore, the thrust generated by the rotation of the rotor device fixed to the support rod on the tower is used to simulate the thrust of the wind acting on the blades of the floating vertical axis wind turbine.
[0051] Based on the body-following coordinate system of the floating vertical axis wind turbine, in order to simulate the six-degree-of-freedom aerodynamic load of the floating vertical axis wind turbine, the rotor device of the aerodynamic load simulation device designed in this application adopts a geometrically symmetrical layout structure. The specific structure of the aerodynamic load simulation device is as follows: Figure 2 As shown, the structural side view of the aerodynamic load simulation device is as follows Figure 3As shown. In one embodiment, the aerodynamic load simulation device includes a crisscross support frame 1, with a height adjustment device 2 provided at the center thereof and secured to a tower 5 via the height adjustment device 2. The crisscross support frame 1 includes two vertically arranged groups of support rods, each group of support rods comprising two mutually parallel support rods, with the distance between the support rods in each group of support rods being d. One group of support rods is arranged along the x-axis of the body-attached coordinate system of the aerodynamic load simulation device, and the other group of support rods is arranged along the y-axis of the body-attached coordinate system of the aerodynamic load simulation device. The origin of the body-attached coordinate system of the aerodynamic load simulation device is located on the tower. The two rotor assemblies 3 on the same side of each group of support rods are installed in opposite directions to ensure that the two rotor assemblies 3 on the same side rotate in opposite directions, thereby offsetting the gyroscopic torque interference simulation results generated by the rotation of a single rotor assemblies 3. Each rotor assemblies 3 includes a motor 301 and rotors 302. The motor 301 drives the rotation speed of the rotors 302 to control the thrust.
[0052] The aerodynamic load simulation device also includes a counterweight device 4, which includes two vertically arranged counterweight struts 402 of identical specifications. Each counterweight strut 402 is provided with a counterweight block 401 at each end. One counterweight strut 402 is arranged along the x-axis of the aerodynamic load simulation device's body coordinate system, and the other counterweight strut 402 is arranged along the y-axis of the aerodynamic load simulation device's body coordinate system. The weight of each counterweight block 401 is determined based on the actual scale weight of the floating vertical axis wind turbine according to a scale ratio λ. The height of the counterweight device 4 is determined based on the actual scale center of gravity height of the floating vertical axis wind turbine according to a scale ratio λ. The length of each counterweight strut 402 is determined based on the actual scale inertia of the floating vertical axis wind turbine according to a scale ratio λ. The actual scale weight, actual scale center of gravity height, and actual scale inertia of the floating vertical axis wind turbine are all known quantities. The specific method is as follows: During the calibration process before the tank test begins, the weight of the counterweight block 401 is adjusted by performing a weighing test on the aerodynamic load simulation device to achieve scaled equivalence of the full-scale weight; the height of the counterweight device 4 is adjusted by performing a tilting test on the aerodynamic load simulation device to achieve scaled equivalence of the full-scale center of gravity; and the length of the counterweight support rod 402 of the counterweight device is adjusted by performing a decay test on the aerodynamic load simulation device to achieve scaled equivalence of the full-scale inertia. After the aerodynamic load simulation device is completed, the tower 5 is fixed to the floating foundation 7 via the six-component force sensor 6 and placed in the test tank to conduct a tank test using the aerodynamic load simulation device to simulate the aerodynamic loads of the floating vertical axis wind turbine.
[0053] Under different wind conditions, the aerodynamic force acts at different heights. Therefore, in order to accurately simulate the tower base bending moment of a floating vertical axis wind turbine under different wind conditions, the present application accurately simulates the aerodynamic arm by setting a height adjustment device to adjust the height of the cross-shaped support frame. In one embodiment, for any simulation time t, the model aerodynamic load includes the model thrust F along the x-axis direction of the body coordinate system of the aerodynamic load simulation device. Xm (t) and the model bending moment M around the x-axis of the body coordinate system of the aerodynamic load simulation device Xm (t); Determine the fixed height of the height adjustment device under the target working condition Then, the model bending moment at each simulation moment can be simulated by multiplying the model thrust by the fixed height.
[0054] Step 3: For any simulation time t, based on the thrust generated by each rotor device meeting the requirements of the model aerodynamic load at the simulation time t, determine the constraint conditions of the aerodynamic load simulation; based on the thrust smoothness of each rotor device at the simulation time t and the thrust balance of all rotor devices at the simulation time t, determine the objective function of the aerodynamic load simulation. The smaller the objective function, the higher the thrust smoothness of each rotor device and the higher the thrust balance of all rotor devices.
[0055] The thrust generated by the rotor devices on the symmetrically arranged cross-shaped support frame is used to simulate the model aerodynamic load. Specifically, the thrust distribution of each rotor device is determined according to the model aerodynamic load. In one embodiment, the thrust generated by the rotor devices in the x-axis direction of the body coordinate system of the aerodynamic load simulation device is used to simulate the model thrust F in the x-axis direction. Xm (t) and the model torque M around the z-axis Zm (t); The thrust generated by the rotor device in the y-axis direction of the body coordinate system of the aerodynamic load simulation device is used to simulate the model thrust F in the y-axis direction Ym (t). The position and thrust distribution of each rotor device are as follows Figure 4 As shown, Figure 4 Here r1-r8 represent rotor devices 1-8 respectively. Rotor devices 1-4 realize the model thrust F in the x-axis direction. Xm (t), the model thrust F in the y-axis direction is achieved by the rotor device 5-8 Ym (t), and the thrusts generated by rotor devices 5 and 6 are completely consistent, and the thrusts generated by rotor devices 7 and 8 are completely consistent, and the model torque M of the rotation around the z axis achieved by rotor devices 1-4 Zm (t). The constraints for aerodynamic load simulation are determined as follows:
[0056]
[0057] Among them, F1(t) and F2(t) are the thrusts generated by the rotor devices (rotor devices 1 and 2) arranged at the starting end points of the two support rods in the x-axis direction of the body coordinate system of the aerodynamic load simulation device, F3(t) and F4(t) are the thrusts generated by the rotor devices (rotor devices 3 and 4) arranged at the ending end points of the two support rods in the x-axis direction of the body coordinate system of the aerodynamic load simulation device, F5(t) and F6(t) are the thrusts generated by the rotor devices (rotor devices 5 and 6) arranged at the ending end points of the two support rods in the y-axis direction of the body coordinate system of the aerodynamic load simulation device, and F7(t) and F8(t) are the thrusts generated by the rotor devices (rotor devices 7 and 8) arranged at the starting end points of the two support rods in the y-axis direction of the body coordinate system of the aerodynamic load simulation device; for the thrust F generated by any rotor device i i (t)≥0.
[0058] In order to prevent the sudden change of the model aerodynamic load in turbulent wind conditions from affecting the test, it is necessary to ensure that the thrust of each rotor device changes smoothly and that the thrust of all rotor devices is balanced. In one embodiment, the thrust smoothness f of any rotor device i at any simulation time t is calculated. i (t), and the thrust balance degree g(t) of all rotor devices at any simulation time t, the objective function of aerodynamic load simulation is determined as:
[0059]
[0060] Where T is the simulation duration, α is the thrust allocation weight, t is an integer parameter with the value 1≤t≤T, and i is an integer parameter with the value 1≤i≤8. The thrust allocation weight α can be customized based on the emphasis on thrust smoothness and thrust balance. To prioritize thrust smoothness, set α to < 1; to prioritize thrust balance, set α to > 1.
[0061] Since the equation system of formula (1) contains 8 unknowns and 5 equations, the solution obtained by solving this equation system is not a unique solution, but multiple different solutions. Based on this design, more options are provided for the optimization algorithm to solve the optimal solution, which can improve the accuracy of the optimal solution obtained. By introducing the dual constraints of time and space dimensions to design the objective function, it is possible to ensure that solving this objective function under the constraints can obtain the optimal thrust combination of each rotor device that meets the requirements of thrust smoothness and thrust balance, thereby ensuring the stability of the tank test and the reliability of the simulation results.
[0062] In one embodiment, the thrust F generated by the rotor device i at the simulation time t i (t) and the thrust F generated by the rotor device i at the simulation time t-1 i(t-1), determine the thrust smoothness f of rotor device i at simulation time t i (t)=(F i (t)-F i (t-1)) 2 By expressing the mathematical form of the sum of squares of thrust changes in the time dimension, the effect of suppressing thrust mutation fluctuations can be achieved.
[0063] By limiting the difference in thrust of all rotors at the same time, the load of each rotor can be balanced. In one embodiment, the maximum thrust F generated by all rotors at the simulation time t is determined. max (t) and the minimum thrust F min (t), and then determine the thrust balance degree of all rotor devices at the simulation time t g(t) = (F max (t)-F min (t)) 2 During the optimization process, the gap between the maximum thrust and the minimum thrust of all rotor devices is continuously reduced until the thrust difference between any two rotor devices in all rotor devices is small enough, thereby achieving a balanced thrust state for all rotor devices.
[0064] Step 4: Based on the above constraints, use the quadratic programming method to solve the candidate thrust generated by each rotor device when the objective function is minimized.
[0065] By solving formula (1) and formula (2), the thrust F1(t) to F8(t) that each rotor device needs to provide at each simulation moment can be calculated as the candidate thrust generated by each rotor device.
[0066] Step 5: Place the aerodynamic load simulation device in the test pool and control the rotation of each rotor device to generate candidate thrust; use a six-component force sensor to measure the actual aerodynamic load generated by the aerodynamic load simulation device at the bottom of the tower, and calculate the simulation error between the actual aerodynamic load and the model aerodynamic load.
[0067] The rotor's rotation is controlled using a control system consisting of a host computer, a single-chip microcomputer, and electronic speed controllers (ESCs). The specific control method is as follows: the host computer calculates the time series of the control signal for the model's aerodynamic load, the SCM receives the PWM wave generated by the corresponding signal, and the ESC adjusts the rotor's motor speed based on the duty cycle of the received PWM wave. Specifically, the throttle signal is first increased from small to large, and the thrust value under each throttle signal is tested to form a "throttle signal-thrust" curve. The candidate thrust time series generated by each rotor obtained in step 4 is then mapped onto this curve to obtain the corresponding throttle signal history for each rotor, thereby enabling real-time dynamic control of the thrust generated by each rotor.
[0068] Under the thrust generated by each rotor assembly, a six-component force sensor is used to measure the six-degree-of-freedom aerodynamic loads generated by the aerodynamic load simulation device at the tower base to obtain the measured aerodynamic load values. Considering that the thrust along the x-axis, the thrust along the y-axis, and the torque rotating about the z-axis in the six-degree-of-freedom aerodynamic loads have the greatest impact on the simulation results, in one embodiment, the simulation error e(t) between the measured aerodynamic load values and the model aerodynamic loads at simulation time t is determined as:
[0069]
[0070] Among them, F′ Xm (t) is the measured thrust along the x-axis of the body coordinate system of the aerodynamic load simulation device, F′ Ym (t) is the measured thrust along the y-axis of the body coordinate system of the aerodynamic load simulation device, M′ Xm (t) is the measured value of the torque rotating around the z-axis of the body coordinate system of the aerodynamic load simulation device.
[0071] Step 6: Correct the thrust generated by each rotor assembly according to the simulation error until the simulation error is no greater than the error threshold, and obtain the aerodynamic load of the floating vertical axis wind turbine at the simulation time t.
[0072] To further ensure the accuracy of the simulation results, real-time detection of simulation errors is required. A closed-loop feedback mechanism dynamically adjusts the thrust of each rotor unit based on real-time data from the six-component force sensor at the tower base. This not only prevents the accumulation of deviations in the simulation results, ensuring accuracy, but also allows for rapid adjustment of thrust distribution among the remaining rotor units if a rotor unit fails, achieving fault tolerance and preventing system crashes, ensuring the safe and stable completion of the test.
[0073] In one embodiment, the thrust generated by each rotor device is corrected according to the simulation error, including: when the simulation error is greater than the error threshold, adjusting the thrust distribution weight α of the objective function J, and recalculating the candidate thrust generated by each rotor device when the objective function is minimized using a quadratic programming algorithm, to obtain the corrected thrust generated by each rotor device. In a specific test process, the value of the thrust distribution weight α can be adjusted empirically or iteratively, for example, by setting a minimum and maximum value of α, such as [0.1, 10], and allowing α to start from the minimum value and continuously increase the value of α according to a specified step size, iteratively solving the objective function and calculating the simulation error until the error threshold is met to obtain the optimal thrust of each rotor device. The error threshold can be customized according to actual application requirements. In this application, the error threshold is set to 5%.
[0074] The thrust timing curves of each rotor device calculated using the optimization algorithm of this application are as follows: Figure 6The thrust distribution results for each rotor unit follow the principle of minimizing the thrust changes of each rotor unit between adjacent simulation moments. This ensures that the speed of the motor-driven rotor does not change too quickly between adjacent simulation moments, thus preventing the problem of aerodynamic loads not being able to be reproduced in a timely manner.
[0075] The thrust distribution mechanism with closed-loop feedback is used to suppress sudden thrust changes, and the simulation results are evaluated by calculating the thrust change rate between adjacent simulation moments. The thrust change rate is calculated as follows:
[0076]
[0077] Where ΔF i (t) is the rate of change of thrust of rotor device i at simulation time t, and max() indicates the maximum value.
[0078] This application calculated the thrust rate of change without and with the thrust smoothness constraint. The average thrust rate of change for each rotor assembly without the thrust smoothness constraint was 28.8%, while the average thrust rate of change for each rotor assembly with the thrust smoothness constraint was 9.3%. Comparing the calculation results shows that the thrust smoothness constraint introduced in this application can effectively reduce the thrust rate of the rotor assembly and ensure thrust smoothness.
[0079] The thrust generated by the eight rotor devices at each simulation moment is further statistically processed to obtain the thrust distribution box-line diagram of each rotor device as shown in the following figure: Figure 7 As shown. The figure shows that the median thrust of rotor device 2 is the highest, indicating that this rotor device plays a major role in load distribution. Subsequent optimization can consider using different specifications for rotor device 2 and the other seven rotor devices to improve performance. The thrust standard deviation analysis shows that the degree of discreteness of rotor devices 5-8 is lower than that of rotor devices 1-4, which is directly related to the thrust symmetry constraint design along the y-axis. The method of this application can effectively improve the accuracy of aerodynamic load simulation of floating vertical axis wind turbines and provide scientific data analysis guidance for subsequent optimization design.
[0080] The above description is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and variations directly derived or imagined by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the scope of protection of the present application.
Claims
1. A test method for simulating the aerodynamic load of a floating vertical axis wind turbine using multi-rotor thrust synergy, characterized in that: The test method includes: Calculate the real-scale aerodynamic load of the floating vertical axis wind turbine at the tower bottom at each simulation time under the target operating conditions, and reduce the real-scale aerodynamic load to the model scale according to the scale ratio λ to obtain the model aerodynamic load at each simulation time; An aerodynamic load simulation device is manufactured, comprising a six-component force sensor mounted at the bottom of a tower, a tower frame fixedly connected to the six-component force sensor, and a plurality of support rods of the same specifications fixed to the tower frame, wherein a rotor device is provided at each end of each support rod, and a rotation plane of the rotor device is perpendicular to the support rod; For any simulation time t, the constraints of the aerodynamic load simulation are determined based on the thrust generated by each rotor assembly meeting the requirements of the model aerodynamic load at the simulation time t; The objective function of the aerodynamic load simulation is determined based on the thrust smoothness of each rotor device at the simulation time t and the thrust balance of all rotor devices at the simulation time t. The smaller the objective function, the higher the thrust smoothness of each rotor device and the higher the thrust balance of all rotor devices. Based on the constraints, a quadratic programming method is used to solve the candidate thrust generated by each rotor device when the objective function is minimized; The aerodynamic load simulation device is placed in a test water tank, and the rotation of each rotor device is controlled to generate a candidate thrust. The actual aerodynamic load generated by the aerodynamic load simulation device at the bottom of the tower is measured using a six-component force sensor, and the simulation error between the actual aerodynamic load value and the model aerodynamic load is calculated. The thrust generated by each rotor device is corrected according to the simulation error until the simulation error is no greater than an error threshold, thereby obtaining the aerodynamic load of the floating vertical axis wind turbine at the simulation time t.
2. The test method according to claim 1, characterized in that The aerodynamic load simulation device includes a crisscross support frame, a height adjustment device is provided at the center of the crisscross support frame and is fixed to the tower through the height adjustment device; the crisscross support frame includes two groups of support rods arranged vertically, each group of support rods includes two mutually parallel support rods, and the spacing between the support rods of each group is d; one group of support rods is arranged in the x-axis direction of the body coordinate system of the aerodynamic load simulation device, and the other group of support rods is arranged in the y-axis direction of the body coordinate system of the aerodynamic load simulation device, the origin of the body coordinate system of the aerodynamic load simulation device is located on the tower, and the two rotor devices on the same side of each group of support rods rotate in opposite directions; The aerodynamic load simulation device also includes a counterweight device, which includes two vertically arranged counterweight struts of the same specifications, with counterweight blocks arranged at both ends of each counterweight strut, one counterweight strut is arranged along the x-axis direction of the body coordinate system of the aerodynamic load simulation device, and the other counterweight strut is arranged along the y-axis direction of the body coordinate system of the aerodynamic load simulation device; the weight of each counterweight block is determined according to the scale ratio λ based on the actual scale weight of the floating vertical axis wind turbine, the height of the counterweight device is determined according to the scale ratio λ based on the actual scale center of gravity height of the floating vertical axis wind turbine, and the length of each counterweight strut is determined according to the scale ratio λ based on the actual scale inertia of the floating vertical axis wind turbine.
3. The test method according to claim 2, characterized in that For any simulation time t, the model aerodynamic load includes the model thrust F along the x-axis direction of the body coordinate system of the aerodynamic load simulation device. Xm (t) and the model bending moment M around the x-axis of the body coordinate system of the aerodynamic load simulation device Xm (t); Determine the fixed height of the height adjustment device under the target working condition 4. The test method according to claim 3, characterized in that The model aerodynamic load also includes a model thrust F along the y-axis direction of the body coordinate system of the aerodynamic load simulation device. Ym (t) and the model torque M rotating around the z-axis of the body coordinate system of the aerodynamic load simulation device Zm (t); The thrust generated by the rotor device in the x-axis direction of the body coordinate system of the aerodynamic load simulation device is simulated by the model thrust F in the x-axis direction Xm (t) and the model torque M around the z-axis Zm (t); The thrust generated by the rotor device in the y-axis direction of the body coordinate system of the aerodynamic load simulation device is simulated by the model thrust F in the y-axis direction Ym (t); The constraints for aerodynamic load simulation are determined as follows: Among them, F1(t) and F2(t) are the thrusts generated by the rotor devices at the starting end points of the two support rods arranged in the x-axis direction of the body coordinate system of the aerodynamic load simulation device, F3(t) and F4(t) are the thrusts generated by the rotor devices at the ending end points of the two support rods arranged in the x-axis direction of the body coordinate system of the aerodynamic load simulation device, F5(t) and F6(t) are the thrusts generated by the rotor devices at the ending end points of the two support rods arranged in the y-axis direction of the body coordinate system of the aerodynamic load simulation device, and F7(t) and F8(t) are the thrusts generated by the rotor devices at the starting end points of the two support rods arranged in the y-axis direction of the body coordinate system of the aerodynamic load simulation device; for the thrust F generated by any rotor device i i (t)≥0.
5. The test method according to claim 1, characterized in that The thrust smoothness f of any rotor device i at any simulation time t i (t), and the thrust balance degree g(t) of all rotor devices at any simulation time t, determine the objective function of aerodynamic load simulation T is the simulation duration, α is the thrust distribution weight, t is an integer parameter with 1≤t≤T, and i is an integer parameter with 1≤i≤8.
6. The test method according to claim 5, characterized in that According to the thrust F generated by the rotor device i at the simulation time t i (t) and the thrust F generated by the rotor device i at the simulation time t-1 i (t-1), determine the thrust smoothness f of rotor device i at simulation time t i (t)=(F i (t)-F i (t-1)) 2 .
7. The test method according to claim 5, characterized in that Determine the maximum thrust F generated by all rotor devices at the simulation time t max (t) and the minimum thrust F min (t), determine the thrust balance degree of all rotor devices at the simulation time t g(t) = (F max (t)-F min (t)) 2 .
8. The test method according to claim 5, characterized in that Correcting the thrust generated by each rotor assembly according to the simulation error includes: When the simulation error is greater than the error threshold, the thrust distribution weight α of the objective function J is adjusted, and the candidate thrust generated by each rotor device when the objective function is minimized is recalculated using the quadratic programming algorithm to obtain the corrected thrust generated by each rotor device.
9. The test method according to claim 1, characterized in that The model aerodynamic load includes a model thrust F along the x-axis direction of the body coordinate system of the aerodynamic load simulation device. Xm (t), model thrust F along the y-axis direction of the body coordinate system of the aerodynamic load simulation device Ym (t) and the model torque M rotating around the z-axis of the body coordinate system of the aerodynamic load simulation device Zm (t); Determine the simulation error e(t) between the measured value of the aerodynamic load and the model aerodynamic load at the simulation time t: Among them, F′ Xm (t) is the measured value of the thrust along the x-axis direction of the body coordinate system of the aerodynamic load simulation device, F′ Ym (t) is the measured thrust value along the y-axis direction of the body coordinate system of the aerodynamic load simulation device, M′ Xm (t) is the measured value of the torque rotating around the z-axis of the body coordinate system of the aerodynamic load simulation device.
10. The test method according to claim 1, characterized in that The real-scale aerodynamic load at any simulation time t includes the real-scale thrust F along the x-axis direction of the body coordinate system of the floating vertical axis wind turbine. X (t), the real-scale thrust F along the y-axis direction of the body coordinate system of the floating vertical axis wind turbine Y (t), the real-scale torque M around the z-axis of the floating vertical axis wind turbine's body coordinate system Z (t) and the real-scale bending moment M around the x-axis of the body coordinate system of the floating vertical axis wind turbine X (t); The model aerodynamic load at the simulation time t includes the model thrust F along the x-axis direction of the body coordinate system of the aerodynamic load simulation device Xm (t), model thrust F along the y-axis direction of the body coordinate system of the aerodynamic load simulation device Ym (t), the model torque M rotating around the z-axis of the body coordinate system of the aerodynamic load simulation device Zm (t) and the model bending moment M around the x-axis of the body coordinate system of the aerodynamic load simulation device Xm (t); Determine the model thrust according to the scale ratio λ Determine model thrust Determine the model torque Determine the model bending moment The scale ratio λ>1.