A hybrid model test method for offshore wind turbines applicable to various foundation types

Abstract

The application discloses a kind of offshore wind turbine hybrid model test methods for a variety of basic types, applicable to different types of offshore wind turbine indoor model test such as bottom sitting type and floating type.The method of the application mainly includes the following steps: (1) determining the experimental scale ratio and processing the physical model; (2) selecting indoor wave pool and wave condition calibration; (3) physical model and actuator hoisting approach; (4) arranging optical measurement system; (5) iterative calculation of blade element momentum model in aerodynamics and overall test development.Through the information interaction of blade element momentum model, physical model and actuator in the truncated part in aerodynamics, the load and motion response of the real wind turbine can be reflected.The application solves the problems of non-uniform scale, blade structure processing difficulty and other series of problems in offshore wind turbine indoor model test, and is widely applicable, efficient and reliable.

Description

Technical Field

[0001] This invention belongs to the field of offshore wind power generation technology, specifically relating to a method for indoor real-time hybrid model testing of multi-degree-of-freedom offshore wind turbines. Background Technology

[0002] Offshore wind power development is an important measure to achieve my country's goals of "carbon peaking" and "carbon neutrality". According to the results of the wind energy resource survey, my country has high-quality and abundant marine wind energy resources. The development potential of offshore wind power in my country at water depths of 5-25 meters and heights of 50 meters is about 200 million kilowatts; the development potential of offshore wind power at water depths of 5-50 meters and heights of 70 meters is about 500 million kilowatts.

[0003] Offshore wind turbine foundations are the supporting structures that ensure the stable and safe operation of the turbines. They are mainly divided into two types: bottom-mounted and floating. Offshore wind turbines are subjected to various loads, including aerodynamic and hydrodynamic loads, in the ocean. To accurately simulate the real loads experienced by offshore wind turbines, indoor water tank model tests are necessary. Traditional water tank model tests usually use Froude similarity scaling to simulate hydrodynamic loads, which conflicts with the Reynolds similarity used to simulate aerodynamic loads of wind turbines. This results in the aerodynamic loads experienced by the model wind turbine under Froude similarity being often underestimated. At the same time, the model wind turbine under Froude similarity has very high requirements for the mass control of the superstructure, which makes blade manufacturing, sensor installation, and controller integration challenging. Furthermore, due to limitations in the marine environment simulation capabilities of wave tanks, it is usually difficult to simulate the magnitude, direction, spatiotemporal distribution, and coupling effects of multi-degree-of-freedom wind-wave-current. Water tank model tests face challenges in fidelity, controllability, and accuracy. Summary of the Invention

[0004] To address the problems existing in existing water tank model tests and numerical simulations, this invention proposes a hybrid model test method for offshore wind turbines of various basic types. It is applicable to indoor model tests of different types of offshore wind turbines, such as bottom-mounted and floating types. Based on this method, the integrated simulation and analysis of the multi-degree-of-freedom dynamic response of offshore wind turbines can be effectively realized.

[0005] This invention is achieved using the following technical solution:

[0006] A hybrid model testing method for offshore wind turbines applicable to various basic types, comprising the following steps:

[0007] First, based on the simulated wind spectrum conditions, the blade element momentum model in aerodynamics is used to calculate the multi-degree-of-freedom aerodynamic loads at the top of the wind turbine tower according to the aerodynamic and structural parameters of the selected wind turbine airfoil; the multi-degree-of-freedom aerodynamic loads include aerodynamic thrust and aerodynamic torque.

[0008] Next, the actuator loads the physical model with the magnitude of the multi-degree-of-freedom aerodynamic load at the top of the wind turbine tower under a given wind condition, based on the blade element momentum model in aerodynamics. It collects the motion response and load response information of the physical model, amplifies the collected information, and feeds it back to the blade element momentum model in aerodynamics for correction of the multi-degree-of-freedom aerodynamic load at the top of the wind turbine tower in the next time step. The corrected multi-degree-of-freedom aerodynamic load at the top of the wind turbine tower is then sent to the actuator after being scaled down from the model. This process is repeated until the predetermined test time.

[0009] The blade element momentum model in the aerodynamics section includes a three-dimensional unsteady wind field module, an aeroelastic dynamic response module, and a variable speed and pitch control module. The three-dimensional unsteady wind field module simulates the turbulent wind field within the wind turbine space and sends the wind field data to the aeroelastic dynamic response module. The aeroelastic dynamic response module solves for the aerodynamic loads and elastic deformations of the wind turbine blade structure in real time based on the obtained wind field data and transmits the aerodynamic load and elastic deformation data to the variable speed and pitch control module. The variable speed and pitch control module uses a PID algorithm to solve for the wind turbine, generator shaft speeds, and blade pitch angles based on the obtained aerodynamic load and elastic deformation data, and adjusts the multi-degree-of-freedom aerodynamic loads based on the blade pitch angles to achieve optimal wind turbine efficiency or rated power capture.

[0010] In the above technical solution, the physical model further includes a wind turbine tower, a wind turbine foundation, and an anchor line; the physical model is placed in a wave pool; the physical model satisfies the Froude similarity criterion, which can be specifically described by formula (1):

[0011]

[0012] In the formula, C is the characteristic velocity; L is the characteristic scale; g is the gravitational acceleration; Fr p With Fr m This represents the Froude number that satisfies gravity similarity at both the actual and model scales.

[0013] Furthermore, the actuator includes a multi-degree-of-freedom loading actuator, a six-dimensional force sensor, an optical measurement system, an industrial control computer, and a central control computer. The multi-degree-of-freedom loading actuator is an inverted multi-degree-of-freedom electric cylinder parallel vibration table, which is inverted on the top of the wind turbine tower of the physical model by a gantry crane. The multi-degree-of-freedom load on the top of the wind turbine tower is applied through its forward and backward displacement and pitch control. The six-dimensional force sensor is used to measure the load on the top of the wind turbine tower of the physical model and to calibrate the load applied by the multi-degree-of-freedom loading actuator. The optical measurement system is a three-dimensional motion dynamic capture system composed of multiple cameras, used to collect six-degree-of-freedom drift and rotation response information of the physical model, including sway, pitch, heave, roll, and yaw. The central control computer is used for data storage between the six-dimensional force sensor, the optical measurement system, the multi-degree-of-freedom loading actuator, and the blade element momentum model in aerodynamics, and to filter and reduce noise in the interactive data. The industrial control computer is connected to the central control computer and is used to send motion commands to the multi-degree-of-freedom loading actuator.

[0014] This invention divides the wind turbine into upper and lower parts by cutting it off at a certain point. The upper structure is simulated using a numerical model (i.e., the blade element momentum model in aerodynamics), while the lower structure is designed as an actual physical model. That is, the aerodynamic loads of the upper structure are calculated in the numerical model, and the hydrodynamic loads and the aerodynamic loads calculated by the numerical model are applied in the physical model. This invention fully combines the advantages of numerical simulation and model testing, and can effectively solve problems such as scale conflict.

[0015] The beneficial effects of this invention are:

[0016] (1) It solves the problem of scale conflict between aerodynamic load and hydrodynamic load in traditional water tank test, and is applicable to various types of offshore wind turbines such as floating and bottom-mounted.

[0017] (2) No additional wind turbine blade model is required, thus avoiding manufacturing process issues such as blade quality and strength.

[0018] (3) It can apply multi-degree-of-freedom loads to the top of the tower and takes into account the influence of control strategies, making it closer to the real situation. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of information interaction between different parts of the system of the present invention.

[0020] Figure 2 This is a schematic diagram of the overall system layout of the present invention, wherein a is a system layout diagram of the floating wind turbine foundation and b is a system layout diagram of the bottom-mounted wind turbine foundation.

[0021] Figure 3 This is a top view schematic diagram of the overall system layout of the present invention.

[0022] In the diagram: 1 is a gantry crane, 2 is a high-strength bolt, 3 is a multi-degree-of-freedom loading actuator, 4 is a spherical hinge, 5 is a six-dimensional force sensor, 6 is a wind turbine tower model, 7a is a floating wind turbine foundation, 7b is a bottom-mounted wind turbine foundation, 8 is an anchor line, 9 is a wave pool, 10 is an artificial seabed topography in the pool, 11 is a wave generator, 12 is a wave-absorbing wall, 13 is an optical measurement system, 14 is a central control computer, 15 is an industrial control computer, and 16 is an ISA bus. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings. Specific embodiments of the present invention include the following steps:

[0024] Step 1: Determine the experimental scaling ratio and process the physical model according to the scaling principle determined by formula (1), including the wind turbine tower 6, the wind turbine foundation 7 (floating or bottom-mounted) and the mooring line 8.

[0025]

[0026] Step 2: Select the indoor wave pool 9 and calibrate the wave conditions according to the scaled water depth; for the floating wind turbine foundation 7a, the wave pool includes a wave generator and a wave-absorbing wall; for the bottom-mounted wind turbine foundation 7b, an artificial seabed topography 10 needs to be built in the wave pool 9; then conduct simulation tests of the waves generated by the wave pool 9, including calibration of different wave periods and wave heights for regular and irregular waves; use a wave height meter to measure the wave data in the wave pool, conduct spectral analysis on the obtained data, and repeatedly generate waves until the designed wave spectrum equals the target wave spectrum;

[0027] Step 3: The physical model and actuators are hoisted to the site; the overall test layout main view is as follows. Figure 2As shown. The physical model and actuator constitute the test device; for the floating wind turbine foundation 7a, the test device, from top to bottom, includes a gantry crane 1, a multi-degree-of-freedom loading actuator 3, a spherical hinge 4, a six-dimensional force sensor 5, a wind turbine tower 6, the floating wind turbine foundation 7a, an anchor line 8, and a wave pool 9; for the bottom-mounted wind turbine foundation 7b, the test device, from top to bottom, includes a gantry crane 1, a multi-degree-of-freedom loading actuator 3, a spherical hinge 4, a wind turbine tower 6, the bottom-mounted wind turbine foundation 7b, a wave pool 9, and an artificial seabed topography 10 in the pool; specifically, the lower part of the gantry crane 1 is connected to the upper steel plate of the multi-degree-of-freedom loading actuator 3 by multiple high-strength bolts 2 to ensure sufficient support strength. The lower part of the multi-degree-of-freedom loading actuator 3 is connected to the wind turbine tower 6 through a spherical hinge 4. The multi-degree-of-freedom loading actuator 3 transmits the multi-degree-of-freedom load to the wind turbine tower 6 through the spherical hinge 4 by controlling its forward and backward displacement and pitch. The six-dimensional force sensor 5 is arranged between the spherical hinge 4 and the wind turbine tower 6 to measure the load on the interface between the two in real time, thereby verifying the accuracy of the load applied by the multi-degree-of-freedom loading actuator 3.

[0028] Step 4: Set up the optical measurement system, such as... Figure 3 The optical measurement system 13 is arranged on both sides of the wave pool 9 to measure the six-degree-of-freedom motion response data of the physical model in real time, including sway, pitch, heave, roll, and yaw. The industrial control computer 15 and the central control computer 14 are connected to the optical measurement system 13, the multi-degree-of-freedom loading actuator 3, and the six-dimensional force sensor 5 through the ISA bus to collect, store, and post-process the data, and transmit all of it to the blade element momentum model in aerodynamics for iterative calculation.

[0029] Step 5: Iterative calculation of the blade element momentum model in aerodynamics and overall test implementation; determine the test wind, wave and flow environment conditions, and start the calibrated wave generator; within the current time step, use the blade element momentum model in aerodynamics to calculate the magnitude of the multi-degree-of-freedom load on the top of the wind turbine tower 6 under the given wind spectrum conditions, and after scaling down the model, send motion commands to the multi-degree-of-freedom loading actuator 3 via the industrial control computer 15; upon receiving the command, the multi-degree-of-freedom loading actuator 3 immediately applies load to the wind turbine tower 6, and the wind turbine foundation undergoes a motion response after being loaded, which is collected by the optical measurement system 13 in six dimensions. Force sensor 5 simultaneously collects the interface load magnitude; the collected data is transmitted in real time to the central control computer 14 via ISA bus 16; the blade element momentum model in aerodynamics amplifies the collected interface load and model motion response information and feeds it back to the blade element momentum model in aerodynamics, thereby correcting the multi-degree-of-freedom load of the wind turbine tower in the next time step. After the model is scaled down, the command is sent again to the multi-degree-of-freedom loading actuator 3 via industrial control computer 15; the correction and loading steps are repeated until the predetermined simulation time is reached, and the relevant data are synchronously stored in the central control computer 14.

[0030] The overall information interaction and transmission mode of the three parts—numerical model, physical model, and actuator—during the experiment is as follows: Figure 1 As shown.

Claims

1. A method for hybrid model testing of offshore wind turbines applicable to a variety of foundation types, characterized in that, The method comprises the following steps: Firstly, according to the simulated wind spectrum working condition, the multi-degree-of-freedom aerodynamic load at the top of the wind turbine tower is calculated by using the blade element momentum model in aerodynamics and according to the selected aerodynamic and structural parameters of the wind turbine airfoil; the multi-degree-of-freedom aerodynamic load comprises an aerodynamic thrust and an aerodynamic torque; Then, the physical model is loaded by the multi-degree-of-freedom aerodynamic load at the top of the wind turbine tower calculated by the blade element momentum model in aerodynamics under the given wind condition, the motion response and load response information of the physical model are collected, the collected information is fed back to the blade element momentum model in aerodynamics after being enlarged by the model, the multi-degree-of-freedom aerodynamic load at the top of the wind turbine tower after being corrected is sent to the actuator after being scaled down by the model, and the process is repeated until the predetermined test time is reached; The blade element momentum model in aerodynamics comprises a three-dimensional unsteady wind field module, an aeroelastic dynamic response module and a variable speed variable pitch control module; the three-dimensional unsteady wind field module is used to simulate the turbulent wind field in the wind wheel space and send the wind field data to the aeroelastic dynamic response module; the aeroelastic dynamic response module solves the wind turbine blade structure aerodynamic load and elastic deformation in real time according to the obtained wind field data, and transmits the aerodynamic load and elastic deformation data to the variable speed variable pitch control module; the variable speed variable pitch control module solves the wind wheel, generator shaft speed and blade pitch angle through the PID algorithm according to the obtained aerodynamic load and elastic deformation data, and adjusts the multi-degree-of-freedom aerodynamic load based on the blade pitch angle, so as to realize the optimal efficiency or rated power capture of the wind turbine.

2. A hybrid model testing method for offshore wind turbines applicable to a variety of foundation types according to claim 1, characterized in that, The physical model comprises a wind turbine tower, a wind turbine foundation and an anchor line; the physical model is placed in a wave pool; the physical model satisfies the Froude similarity criterion, which can be described by formula (1): where C is the characteristic velocity; L is the characteristic length scale; g is the gravitational acceleration; Fr p Fr m is the Froude number for the actual and model scales that satisfy the gravitational similarity.

3. A hybrid model testing method for offshore wind turbines applicable to a variety of foundation types according to claim 2, characterized in that, The actuator comprises a multi-degree-of-freedom loading actuator, a six-dimensional force sensor, an optical measurement system, an industrial computer and a total control computer; the multi-degree-of-freedom loading actuator is a multi-degree-of-freedom electric cylinder parallel vibration table, which is inverted and buckled on the top of the wind turbine tower of the physical model through the gantry crane, and the multi-degree-of-freedom load at the top of the wind turbine tower is applied through the front and rear displacement and pitch control; the six-dimensional force sensor is used to measure the load borne by the wind turbine tower at the top of the physical model, and is used to calibrate the load applied by the multi-degree-of-freedom loading actuator; the optical measurement system is a three-dimensional motion dynamic capture system composed of multiple cameras, which is used to collect the six-degree-of-freedom drift and rotation response information of the physical model, including the sway, surge, heave, roll, pitch and yaw; the total control computer is used for data storage between the six-dimensional force sensor, the optical measurement system, the multi-degree-of-freedom loading actuator and the blade element momentum model in aerodynamics, and filters and denoises the interactive data; the industrial computer is connected with the total control computer, and is used to send motion commands to the multi-degree-of-freedom loading actuator.

4. A hybrid model testing method for offshore wind turbines applicable to a variety of foundation types according to any one of claims 1-3, characterized in that, The method specifically comprises the following steps: Step 1, determining the experimental scale ratio and processing the physical model according to the scale ratio; Step 2, according to the scale water depth to select indoor wave pool and wave condition calibration; for floating wind turbine foundation, the wave pool includes wave maker and wave absorbing wall; for the bottom foundation, the artificial seabed terrain needs to be built in the wave pool; then the simulation test of the wave pool is carried out, including the calibration of regular wave and irregular wave with different wave periods and wave heights; the wave data in the wave pool is measured by wave height instrument, and the obtained data is analyzed by spectrum analysis, and the wave is repeatedly made until the design wave spectrum is equal to the target wave spectrum; Step 3, the physical model and the actuator are hoisted into the field; the physical model and the actuator constitute the test device; for floating wind turbine foundation, the test device from top to bottom includes gantry crane, multi-degree-of-freedom loading actuator, spherical hinge, six-dimensional force sensor, wind turbine tower, wind turbine foundation, anchor line and wave pool; for the bottom foundation, the test device from top to bottom includes gantry crane, multi-degree-of-freedom loading actuator, spherical hinge, wind turbine tower, wind turbine foundation, wave pool and artificial seabed terrain; the lower part of the multi-degree-of-freedom loading actuator is connected with the wind turbine tower through the spherical hinge, and the multi-degree-of-freedom loading actuator transmits the multi-degree-of-freedom load to the wind turbine tower through the spherical hinge by controlling the forward and backward displacement and pitching; the six-dimensional force sensor is arranged between the spherical hinge and the wind turbine tower, which is used for measuring the load on the interface in real time, so as to verify the accuracy of the load applied by the multi-degree-of-freedom loading actuator; Step 4, the optical measurement system is arranged on both sides of the wave pool, which is used for measuring the six-degree-of-freedom motion response data of the physical model, including sway, surge, heave, roll, pitch and yaw; the industrial computer and the general control computer are connected with the optical measurement system, the multi-degree-of-freedom loading actuator and the six-dimensional force sensor through ISA bus, which is used for centralized collection, storage and post-processing of data, and all the data are transmitted to the blade element momentum model in aerodynamics for iterative calculation; Step 5, iterative calculation of the blade element momentum model in aerodynamics and overall test; determine the test wind wave flow environment condition, and start the calibrated wave maker; in the current time step, the blade element momentum model in aerodynamics is used to calculate the multi-degree-of-freedom load size of the wind turbine tower top under the given wind spectrum condition, and the model is scaled and sent to the multi-degree-of-freedom loading actuator through the industrial computer; the multi-degree-of-freedom loading actuator executes the load immediately after receiving the command, and the wind turbine foundation moves in response to the load and is collected by the optical measurement system, and the six-dimensional force sensor collects the interface load size at the same time; the collected data are transmitted to the general control computer in real time through the ISA bus; the interface load and model motion response information collected by the blade element momentum model in aerodynamics are enlarged and fed back to the blade element momentum model in aerodynamics, so as to correct the multi-degree-of-freedom load of the wind turbine tower in the next time step, and the model is scaled and the command is sent to the multi-degree-of-freedom loading actuator through the industrial computer; the step is repeated until the predetermined simulation time is reached, and the related data are stored in the general control computer at the same time.

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