Land-based test device and test method for active ballast system of floating wind turbine

Abstract

This invention provides a land-based test apparatus and method for an active ballast system for floating wind turbines. The apparatus includes a swing frame, a platform hydrostatic stiffness simulator, a floating wind turbine model, a ballast tank, a level sensor, pipes, remote-controlled valves, and a water pump. The swing frame simulates platform rotation, the platform hydrostatic stiffness simulator uses springs for simulation, and the load simulator reproduces the wind, wave, and current load history, achieving an equivalent land-based simulation of the floating wind turbine-ballast coupling system. The test method includes wind, wave, and current load calibration, model assembly and adjustment, platform hydrostatic stiffness simulator calibration, and load adjustment testing. This invention eliminates the need for a water tank or sea trial, is low-cost, has a short cycle time, is repeatable, and can comprehensively verify the control logic and load adjustment effect of the active ballast system.

Description

Technical Field

[0001] The invention relates to the field of floating wind turbine technology, and in particular to the onshore test device and test method for the active ballast system of floating wind turbines. Background Technology

[0002] As floating wind turbines become larger and more powerful, they experience significant swaying under wind loads, leading to power fluctuations, tower fatigue, mooring overload, and even emergency shutdowns. Active ballast systems monitor the platform's attitude in real time and drive pumps and valves to rapidly allocate ballast water between ballast tanks. This generates a righting torque that counteracts the external environmental torque, thus reducing load and improving power generation stability.

[0003] Active ballast systems involve the coupling of multiple disciplines including mechanics, electronics, hydraulics, and control. The control algorithms require long-term verification and optimization tailored to the specific hydrodynamic characteristics, mass distribution, ballast tank design, and environmental loads of the floating wind turbine platform. An untested system, if it experiences control instability at sea, could lead to significant platform movement or even capsizing, turbine shutdown, and power generation losses. Therefore, systematic testing of the active ballast system must be conducted before prototype production and installation on a real vessel to verify the correctness and robustness of the control logic, the rationality of the ballast tank layout and capacity design, and the overall system safety and reliability.

[0004] Currently, the industry mainly employs three testing methods: simple onshore test benches, marine engineering pool model tests, and full-scale sea trials. Onshore simple test benches cannot accurately reproduce the dynamic characteristics of a fully coupled floating wind turbine and active ballast system, and are typically used for single-function tests such as sensor verification. Pool model tests and sea trials are the traditional mainstream methods, but they have inherent drawbacks such as high cost, long testing cycles, and complex operations. Sea trials, in particular, face challenges related to uncontrollable environments and complex regulatory approvals.

[0005] Therefore, we propose an onshore test device and test method for a floating wind turbine active ballast system.

[0006] Application content To address the shortcomings of the prior art, the applicant provides a land-based testing device and method for a floating wind turbine active ballast system, which enables onshore commissioning and verification of the control logic and load adjustment effect of the floating wind turbine active ballast system, facilitating performance evaluation and design improvement of the active ballast system.

[0007] The technical solution adopted in this invention is as follows: A land-based test device for an active ballast system for a floating wind turbine mainly consists of a swing frame, a platform hydrostatic stiffness simulator, a floating wind turbine model, a ballast tank, a liquid level sensor, pipelines, remote control valves, a water pump, and an active ballast control system.

[0008] The swing frame consists of a base, support legs, a cutter head and cutter holder mechanism, connectors, and a frame. The frame supports the floating wind turbine model for subsequent adjustments to its mass parameters and active ballast system testing. Connectors can be symmetrically installed at the top of the frame, both longitudinally and laterally. Each connector is bolted to the lower end of the corresponding cutter head and cutter holder mechanism. The upper end of the cutter head and cutter holder mechanism is bolted to the upper surface of the corresponding support leg. The cutter head of the mechanism has an inverted triangular cross-section, allowing it to rotate around its cutting axis, thus rotating the frame and the floating wind turbine model on it. The lower ends of the support legs are fixed to the base at their corresponding positions.

[0009] The platform's hydrostatic stiffness simulator can be simulated using springs. Its top is connected to the bottom of the swing frame, and the bottom is vertically fixed to the ground. When the swing frame rotates along with the floating wind turbine model, the platform's hydrostatic stiffness simulator will deform and generate a torque to resist the rotation of the floating wind turbine model, thus simulating the hydrostatic stiffness of the floating wind turbine platform in water during rolling and pitching. Several platform hydrostatic stiffness simulators are arranged symmetrically about the rotation axis.

[0010] The floating wind turbine model consists of a platform body, platform column flanges, tower bottom flange, tower, six-component force sensors, load simulator bottom flange, and load simulator. The platform body, a hollow structure, comprises several columns and a lower floating body. Attitude sensors, such as inertial navigation systems and fiber optic gyroscopes, are installed on the platform body to collect and provide real-time feedback on the platform's motion attitude during testing. The platform body and tower are bolted together via the platform column flanges and the tower bottom flange. The six-component force sensors, bolted to the top of the tower, measure the horizontal thrust of the load simulator. The load simulator is bolted to the top of the six-component force sensors via its bottom flange. The load simulator generates thrust by driving a turbine fan with a motor. The horizontal thrust generated by wind and wave currents on the floating wind turbine platform can be simulated by dynamically controlling the fan speed. Under this horizontal thrust, the floating wind turbine model will tilt.

[0011] The ballast water tank is located inside the corresponding column and consists of the tank body, an inlet, and an outlet. The inlet is located at the top of the tank and is used to add ballast water during the test preparation phase. The outlet is located at the bottom of the tank and is connected to other ballast water tanks via pipes, enabling the transfer of ballast water between them. A level sensor is installed inside the ballast water tank and collects real-time level data during the test, which is used by the active ballast control system to formulate ballast control commands. Remote-controlled valves are installed on the pipes and can open or close according to the commands of the active ballast control system, thereby precisely controlling the flow path of ballast water within the pipes. A water pump is installed on the pipes to drive the ballast water flow within them and can open, close, and adjust the flow rate according to the commands of the active ballast control system, enabling the transfer of ballast water between the ballast water tanks. The pipes, valve remote controls, and water pump are located inside the lower buoy.

[0012] A method for onshore testing of a floating wind turbine active ballast system, utilizing the aforementioned onshore testing device for the floating wind turbine active ballast system, includes the following steps: S1, Load simulator speed-thrust calibration: The target thrust time history of the load simulator is obtained by converting the real wind, wave and flow load time history based on the Froude number similarity criterion. Then, the load simulator speed is dynamically controlled by the load simulator speed-thrust characteristic curve to achieve accurate output of the target thrust.

[0013] S2. Assembly of floating wind turbine model: Complete the connection and assembly of the load simulator, six-component force sensor, tower, and platform body. Then, install the ballast tank, level sensor, remote control valve, and water pump inside the floating wind turbine model, and connect the active ballast control system with the attitude sensor, level sensor, remote control valve, and water pump.

[0014] S3. Adjustment and positioning of mass parameters of floating wind turbine model: By adding counterweights to the main body of the floating wind turbine model platform and adjusting their distribution, the weight, center of gravity, and moment of inertia of the floating wind turbine model are adjusted to match the target values. Then, the floating wind turbine model on the swing frame is horizontally rotated to the tilt direction required for the test.

[0015] S5. Installation and stiffness calibration of the platform hydrostatic stiffness simulator: The top of each platform hydrostatic stiffness simulator is installed at the target position of the swing frame, and the bottom is vertically fixed to the ground. Then, the tension value of the test platform hydrostatic stiffness simulator at different swing frame tilt angles is used to obtain the "tilt angle-torque" characteristic curve to ensure that it matches the target hydrostatic stiffness of the floating wind turbine platform.

[0016] S6. Active Ballast System Load Adjustment Test: The load simulator is started to simulate wind, wave and current loads, so that the floating wind turbine model can generate the required tilt angle under these actions. Then, the active ballast control system is started. The active ballast system will automatically open or close the pump valves to allocate ballast water according to the set control logic based on the real-time monitored platform attitude and ballast water tank level. This completes the verification of control logic and system performance.

[0017] Beneficial effects This invention is rationally designed, compact in structure, and easy to operate. It can realistically, quickly, conveniently, economically, and repeatedly verify the control logic of the active ballast system and evaluate the load adjustment effect in a land environment, which helps to reduce early-stage R&D costs and shorten the project cycle.

[0018] (1) Equivalent mapping of multiple physical quantities: This invention uses a platform hydrostatic stiffness simulator to equivalently map the roll and pitch hydrostatic stiffness of the floating wind turbine platform to the land, simulates the tilting motion of the platform through a swing frame, and realizes the accurate reproduction of wind, wave and flow load history through a load simulator, ensuring that the motion and dynamics are similar between the model and the actual model, and providing accurate, reliable and controllable basic conditions for land-based tests.

[0019] (2) Controllable and economical testing: This invention adopts land-based testing, and the maintenance and debugging of related components are convenient. It does not require the use of marine engineering test pools, large lifting equipment, support vessels, etc., and is not limited by weather conditions, which greatly reduces personnel safety risks and test costs.

[0020] (3) Closed-loop verification capability: The test device of the present invention is relocatable and reusable, supports different floating wind turbine models and different scaling ratios, and can realize closed-loop verification of the full functions of sensors, actuators, control algorithms, communication links, etc. in the active ballast system. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention. Figure 2 This is a schematic diagram of the swing frame structure of the present invention. Figure 3 This is a partial structural diagram of the swing frame of the present invention. Figure 4 This is a schematic diagram of the floating wind turbine model structure of the present invention. Figure 5 This is a schematic diagram of ballast water flow in the present invention. Figure 6 This is a top view of the liquid level sensor layout of the present invention. Figure 7 This is a flowchart of the test method of the present invention. Figure 8 This is a comparison chart of the measured thrust and target thrust from the load simulator of this invention. The components include: 1. Swing frame; 2. Platform hydrostatic stiffness simulator; 3. Floating wind turbine model; 4. Adjustable load tank; 5. Liquid level sensor; 6. Pipeline; 7. Remote control valve; 8. Water pump; 11. Base; 12. Support legs; 13. Cutter head and cutter holder mechanism; 14. Connecting parts; 15. Frame; 31. Platform body; 32. Attitude sensor; 33. Platform column flange; 34. Tower bottom flange; 35. Tower; 36. Six-component force sensor; 37. Load simulation device bottom flange; 38. Load simulator; 311. Upright column; 312. Lower floating body; 41. Main body of the water tank; 42. Water inlet; 43. Water outlet. Detailed Implementation

[0022] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0023] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0024] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0025] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0026] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0027] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0028] This invention overcomes the shortcomings of existing pool model tests and sea trials in verifying the effectiveness of active ballast systems for floating wind turbines, such as complex operation, high cost, poor repeatability, and long cycle. It provides a test device and method that can realistically, quickly, conveniently, economically, and repeatedly verify the control logic and evaluate the load adjustment effect of the active ballast system in a land environment. Without relying on a pool or actual sea environment, it can equivalently map the static stiffness and wind, wave, and current loads of the floating wind turbine to the land using a swing frame, a platform static stiffness simulator, and a load simulator. While ensuring that the model and the actual model have similar motion and dynamics, it can achieve closed-loop verification of all functions of the active ballast system, including sensing, control logic, and actuators.

[0029] Example 1 like Figure 1As shown in Figure 6, this embodiment provides a land-based test device for a floating wind turbine active ballast system. The device mainly consists of a swing frame 1, a platform hydrostatic stiffness simulator 2, a floating wind turbine model 3, a ballast tank 4, a liquid level sensor 5, pipes 6, remote control valves 7, and a water pump 8. The components form a closed-loop test system of "support-simulation-execution-monitoring-control". Through physical equivalent mapping, the land-based reproduction of the real marine environment is achieved, which solves the pain points of high cost, long cycle, and uncontrollable environment of traditional tests. It can accurately verify the full-link performance of the active ballast system.

[0030] like Figure 2 As shown, the swing frame 1 in this embodiment consists of two bases 11, two support legs 12, two cutter head and cutter head mechanisms 13, two connectors 14, and a frame 15. The frame 15 is a box-type truss structure made of metal profiles. Its upper surface is used to support the floating wind turbine model 3. The side walls of the frame 15 are connected to the cutter head and cutter head mechanisms 13 and reinforce the overall structure. The box-type truss structure has both lightweight and high strength characteristics, which can avoid the deformation of itself from affecting the test accuracy. The metal profiles are made of high-strength aluminum alloy, which ensures structural rigidity and reduces the overall weight, making it easy to assemble and move the device.

[0031] Two connectors 14 are symmetrically mounted on the top profile sidewall of frame 15 about the longitudinal axis OX of swing frame 1. The cross-section of connector 14 is inverted L-shaped (Figure 3). The side perpendicular to the ground is welded and fixed to the top profile sidewall of frame 15, and the side parallel to the ground is fixedly connected to the lower end of the corresponding cutter head and cutter holder mechanism 13 by bolts. The inverted L-shaped structure can achieve uniform force transmission, the welding fixation ensures connection strength, and the bolt connection facilitates disassembly and maintenance. At the same time, the connection gap can be eliminated by adjusting the bolt preload, thereby improving rotation accuracy. The upper end of the cutter head and cutter holder mechanism 13 is connected to the upper surface of the corresponding support leg 12 by bolts. The cutter head of the cutter head and cutter holder mechanism 13 has an inverted triangular cross-section, allowing the cutter head to rotate around the blade axis. This, in turn, drives the frame 15 and the floating wind turbine model 3 on the frame 15 to rotate around the transverse axis OY of the swing frame 1, simulating the tilting motion of the floating wind turbine under external load. The inverted triangular cutter head design reduces rotational friction resistance, ensuring the smoothness and repeatability of the tilting motion. The blade is made of wear-resistant alloy steel, extending its service life. This rotation mechanism can accurately reproduce typical attitude changes of the floating wind turbine, such as roll and pitch, providing a realistic attitude response scenario for the active ballast system. The support leg 12 is elongated, with its lower end fixed to a square plate base 11 at the corresponding position. A triangular elbow plate is installed between the two to increase structural strength and stability. The square plate base increases the contact area with the ground, reducing ground pressure and preventing base settlement during the test. The triangular elbow plate utilizes the principle of triangular stability to effectively disperse the vertical and horizontal loads transmitted by the support leg, preventing structural damage caused by stress concentration at the connection and ensuring the structural reliability of the swing frame during long-term testing.

[0032] The platform static water stiffness simulator 2 is used to simulate the roll and pitch static water stiffness of a floating wind turbine platform. Its stiffness value is determined by the actual static water stiffness value of the platform, the scale ratio, and the conversion based on the installation position of the platform static water stiffness simulator 2. The accurate conversion of stiffness values ​​is based on the principle of similarity, ensuring consistency between the model and the actual platform's dynamic characteristics. The conversion formula comprehensively considers the influence of structural dimensions, material properties, and installation layout, avoiding distortion of experimental results due to stiffness simulation deviations. The top of the platform static water stiffness simulator 2 is connected to the bottom of the swing frame 1 and frame 15, and the bottom of the platform static water stiffness simulator 2 is vertically fixed to the ground. When the swing frame 1 and frame 15, along with the floating wind turbine model 3, rotate, the platform hydrostatic stiffness simulator 2 will deform and generate a torque to resist the rotation of the floating wind turbine model 3. This simulates the hydrostatic stiffness of the floating wind turbine model 3 in water during roll and pitch. This simulation mechanism uses mechanical deformation to equivalently replace the restoring torque of seawater. Compared with traditional pool tests, it does not depend on the water environment and is not affected by water quality, water temperature, or other factors. Moreover, the stiffness adjustment is flexible, and different types of floating wind turbines can be adapted to test requirements by changing simulators with different stiffness coefficients. In this embodiment, the floating wind turbine model 3 rotates around the OY axis as an example. Therefore, the four platform hydrostatic stiffness simulators 2 are symmetrically arranged about the rotation axis OY. The symmetrical arrangement ensures uniform torque transmission during rotation and avoids model tilting deviation caused by unilateral force. The number of simulators has been optimized through mechanical calculations to ensure the accuracy of stiffness simulation while avoiding excessive redundancy that leads to structural complexity. At the same time, the symmetrical structure facilitates data acquisition and comparison during stiffness calibration.

[0033] As shown in Figure 4, the floating wind turbine model 3 in this embodiment sits on the frame 15 and consists of a platform body 31, platform column flanges 33, tower bottom flanges 34, tower 35, six-component force sensors 36, load simulator bottom flanges 37, and load simulator 38. In this embodiment, the platform body 31 is a four-column semi-submersible configuration, consisting of four columns 311, including three side columns and one central column, and a Y-shaped lower floating body 312. It is also machined into a hollow structure to facilitate the subsequent installation of the drive actuators and wiring of the active ballast system inside. The four-column semi-submersible configuration is a typical structural form of floating wind turbines. The model configuration is consistent with the actual model, which is a necessary condition to ensure similar hydrodynamic characteristics. The hollow structure design reduces the weight of the model and provides sufficient space for internal equipment installation and cable layout, avoiding equipment interference that affects the test operation, while also facilitating later maintenance and component replacement. Attitude sensor 32 is mounted on the upper surface of the bottom flange 34 of the tower. It is used to collect and provide real-time feedback of the platform's motion attitude during the test. The active ballast system then formulates load adjustment commands based on this motion signal. The mounting position at the bottom flange of the tower minimizes the impact of the sensor's own vibration on the measurement, ensuring the accuracy of the attitude data. The attitude sensor uses a high-precision fiber optic gyroscope inertial navigation system, achieving a measurement accuracy of 0.01° and a sampling frequency of 100Hz. It can capture rapid dynamic changes in the platform's attitude, providing high-frequency and accurate feedback signals for the real-time control of the active ballast system. The tower 35 is located on top of the central column 311 of the platform, and the two are bolted together via the platform column flange 33 and the bottom flange 34 of the tower. The height of the tower 35 is determined by the magnitude of the torque corresponding to the wind, wave, and current loads, calculated using the following formula:

[0034] In the formula, It is the height of the tower. and These are the average load values ​​and center height of the wind, wave, and current loads, respectively, defined relative to the bottom of the tower 35.

[0035] A six-component force sensor 36 is bolted to the top of the tower 35 to measure the horizontal thrust generated by the load simulator 38. The six-component force sensor can simultaneously measure three-dimensional force and three-dimensional torque; the focus here is on acquiring horizontal thrust data. The measurement accuracy can reach ±0.1% FS, providing real-time feedback on the thrust output accuracy of the load simulator and offering data support for load calibration and test result verification. The bolted installation method facilitates sensor calibration and replacement. The load simulator 38 is bolted to the top of the six-component force sensor 36 via the bottom flange 37 of the load simulator. The load simulator 38 generates thrust by driving a turbine fan to rotate via a motor. The horizontal force exerted on the floating wind turbine by wind, wave, and current loads can be simulated by dynamically controlling the rotation speed. The floating wind turbine model tilts under this horizontal force. The turbine fan is driven by a high-speed brushless motor with a speed adjustment range of 0-3000 rpm and a response time of less than 200 ms, enabling rapid dynamic adjustment of the thrust and accurately reproducing the time-varying characteristics of wind, wave, and current loads.

[0036] The ballast water tank 4, pipe 6, remote control valve 7, and water pump 8 constitute the ballast water flow channel of the active ballast system, as shown in Figure 5. In this embodiment, three cylindrical ballast water tanks 4 are used, located inside the three side columns 311 of the platform body 31. The structural form and arrangement of the three ballast water tanks are consistent with the ballast tank layout of the actual floating wind turbine, ensuring the effectiveness of the ballast strategy verification. Each ballast water tank 4 consists of a tank body 41, an inlet 42, and an outlet 43. The tank body 41 is made of transparent acrylic material, which facilitates observation of the internal liquid flow during the test. The transparent acrylic material combines high strength and high transparency, allowing for direct observation of the ballast water flow, fluctuations, and level changes. This helps test personnel judge the system's operating status and promptly detect abnormalities such as pipe blockages and valve jamming. At the same time, the acrylic material is resistant to seawater corrosion, extending the service life of the tank. A circular inlet 42 is provided at the top for adding ballast water during the test preparation stage, and an outlet 43 is provided at the bottom for ballast water to be pumped in / out during the test. The inlet is located at the top for rapid water injection, and the outlet is located at the bottom to utilize gravity to assist in the discharge of ballast water, improving ballast efficiency. Both the inlet and outlet are equipped with sealing caps to prevent liquid leakage during the test. The outlet 43 is connected to the pipe 6, thereby connecting the different ballast water tanks 4 and enabling the transfer of ballast water between them. The pipe is made of corrosion-resistant stainless steel, and its inner diameter is designed according to the ballast flow requirements to ensure minimal pressure loss during ballast water flow. The pipe connections are sealed with flanges to prevent liquid leakage from affecting the test accuracy. The pipe layout is optimized to reduce the number of bends and lower flow resistance. Several level sensors 5 (Figure 6) are installed inside each ballast water tank 4. During the test, the tank level data is collected in real time. The active ballast system then calculates the ballast water volume and issues ballast commands based on this level signal. The level sensors are capacitive level gauges with a measurement range of 0-1000 mm and an accuracy of ±1 mm. They are unaffected by changes in liquid density and temperature, exhibiting strong stability and accurately reflecting the tank level, providing reliable data support for the calculation of the ballast water volume. In this embodiment, three liquid level sensors 5 are installed inside each ballast tank 4. One sensor is located at the centroid of the cross-section of the ballast tank 4, and the other four are evenly installed near the side walls along the circumference of the cross-section of the ballast tank 4. The sensor at the centroid is used to obtain the average liquid level in the tank, and the four sensors on the side walls are used to monitor the uniformity of the liquid level to avoid measurement errors caused by liquid sloshing. Through multi-sensor data fusion algorithm, the accuracy and stability of liquid level measurement can be further improved. At the same time, the multi-sensor configuration has redundancy function, and the failure of a single sensor does not affect the overall measurement effect.Remote-controlled valve 7 is installed on pipe 6 and can open or close according to the instructions of the active ballast control system, thereby precisely controlling the flow path of ballast water in pipe 6. The remote-controlled valve is an electric ball valve with a response time of less than 200ms and a switching life of more than 100,000 cycles. It has a position feedback function and can provide real-time feedback on the valve's opening and closing status to the control system to ensure the accurate execution of the control logic. The valve is made of stainless steel, which has strong corrosion resistance and good sealing performance to prevent liquid leakage. Water pump 8 is installed on pipe 6 and is used to drive the ballast water to flow in pipe 6. It can open, close, and adjust the flow rate according to the instructions of the active ballast control system to realize the injection and discharge of ballast water between each ballast water tank 4. The water pump is a variable frequency centrifugal pump with a flow rate adjustment range of 0-2000L / h and a head of 0-12m. It can achieve precise flow rate adjustment through variable frequency control to meet the needs of different ballast scenarios. The water pump has functions such as dry run protection and overload protection to improve operational safety. At the same time, it adopts a low-noise design to reduce noise pollution in the test environment. Pipeline 6, remote control valve 7, and water pump 8 are located inside the lower float 312. The internal space of the lower float is enclosed, which can protect the pipes, valves, and water pump from external environmental interference, while reducing the risk of damage caused by equipment exposure. An internal maintenance passage is reserved to facilitate equipment maintenance and troubleshooting.

[0037] During use, the attitude sensor 32, liquid level sensor 5, remote control valve 7, and water pump 8 are electrically connected to the active ballast control system under test to control the operation of the test device. The electrical connection uses shielded cables to reduce the impact of electromagnetic interference on signal transmission. The control system and each device use a standard communication protocol to ensure the compatibility and reliability of data interaction. It also has a fault diagnosis function, which can monitor the operating status of each device in real time, promptly detect sensor failures, actuator jamming, and other problems, and ensure the smooth progress of the test.

[0038] Example 2: like Figure 7 As shown, this embodiment provides a method for onshore testing of a floating wind turbine active ballast system, utilizing the onshore testing device for the floating wind turbine active ballast system of Embodiment 1, including the following steps: S1, Load simulator 38 RPM-Thrust calibration: 1. Based on the wind, wave, and flow load of the actual floating wind turbine The target thrust of the load simulator 38 in the land test was calculated using the Froude number similarity criterion based on the time period. Time and calendar, such as Figure 8 The target value curve is shown in the figure, and the conversion formula is as follows:

[0039] in, This is the scale ratio of this land-based test. The wind, wave, and current load history of the actual floating wind turbine was calculated using the integrated numerical analysis model of the floating wind turbine. The Froude number similarity criterion is the core similarity criterion for floating structure model tests, ensuring that the gravity-inertial force ratio of the model and the actual turbine is consistent, thereby guaranteeing similar dynamic characteristics. The conversion formula fully considers the influence of the scale ratio on the load, avoiding test deviations caused by scale effects. The integrated numerical analysis model of the floating wind turbine integrates theories from multiple disciplines such as aerodynamics, hydrodynamics, and structural dynamics, and can accurately calculate the wind, wave, and current load history under different sea conditions. Compared with the field measured load data, it has the advantages of low acquisition cost and wide coverage of scenarios, and can provide rich load input scenarios for the test.

[0040] 2. Using the bottom flange 37 of the load simulation device, the load simulator 38 is connected and fixed to the top of the six-component force sensor 36. The flange connection ensures a rigid connection between the load simulator and the sensor, avoiding loosening of the connection due to vibration and ensuring the accuracy of thrust transmission. At the same time, the high coaxiality of the flange connection can reduce the additional torque during the thrust measurement process and improve the measurement accuracy.

[0041] 3. Place the connected device from step 2 in an open area. Use a motor to control the speed of the turbine fan in the load simulator 38, and then test the horizontal thrust of the load simulator 38 at different speeds to obtain the "speed-thrust" characteristic curve. The open area can avoid the interference of surrounding obstacles on the airflow and ensure the accuracy of thrust measurement. The speed adjustment adopts an equal-interval gradient setting to cover the full range of speed of the load simulator. Each speed point is kept running stably for 30 seconds, and multiple sets of thrust data are collected and averaged to reduce the impact of random errors on the characteristic curve. The characteristic curve can intuitively reflect the nonlinear relationship between speed and thrust, providing a basis for subsequent speed control.

[0042] 4. Based on the target thrust time history and the "speed-thrust" characteristic curve of the load simulator 38, the speed change time history of the load simulator 38 is calculated. The calculation process uses an interpolation algorithm to ensure that the speed time history can accurately track the change trend of the target thrust time history. For the nonlinear region of the characteristic curve, piecewise interpolation is used to improve the calculation accuracy and avoid thrust output deviation caused by nonlinearity.

[0043] 5. Develop a dynamic control program for the rotational speed of load simulator 38 to achieve accurate output of the target thrust. Figure 8 shows a comparison diagram between the measured thrust and the target thrust of load simulator 38. The deviation between the measured thrust and the target thrust is controlled within ±3%, meeting the requirements of the test for load reproduction accuracy.

[0044] S2, Floating Wind Turbine Model 3 Assembly: 1. Connect the load simulator 38, in which the six-component force sensor 36 is installed in S1, to the top of the tower 35 in sequence. Then, use the platform column flange 33 and the tower bottom flange 34 to install the tower 35 on the top of the central column 311 of the platform body 31. Install and fix the attitude sensor 32 on the upper surface of the tower bottom flange 34. The assembly process is carried out in the order of "from top to bottom" to ensure the coaxiality and connection reliability of each component. When connecting the flanges, tighten the bolts diagonally and evenly to avoid structural deformation caused by uneven force at the connection. Perform zero-point calibration before installing the sensor to ensure the accuracy of the measurement data.

[0045] 2. Install the level sensors 5 at the target locations in each ballast tank 4, and then install them together inside the platform side column 311. Connect the remote control valve 7 and water pump 8 to the pipe 6 and arrange them together inside the floating body 312 under the platform. Then connect the end of the pipe 6 to the outlet 43 of the corresponding ballast tank 4. After the ballast water flow channel is connected, inject the target amount of ballast water into each ballast tank 4 through the water inlet 42. When installing the level sensors, ensure that the probe does not contact the inner wall of the tank to avoid measurement interference. Perform a pressure test before connecting the pipes to ensure no leakage. Monitor the level sensor data in real time during the water injection process to accurately control the water injection volume and make the initial liquid level of each tank consistent, laying the foundation for the reference state for subsequent ballast tests.

[0046] 3. Connect the active ballast control system to the attitude sensor 32, level sensor 5, remote control valve 7, and water pump 8. This connection is used to control the acquisition of sensor signals and the opening or closing of each drive actuator. At this time, both remote control valve 7 and water pump 8 are in the closed state. After the electrical connection is completed, a communication test is performed to ensure that the data interaction between each device and the control system is normal. The sampling frequency of the sensor signal acquisition is set to match the sampling frequency of the device itself to avoid data loss or redundancy. In the initial state, the valve and water pump are closed to prevent disorderly flow of ballast water and ensure the stability of the initial state of the test.

[0047] S3, Floating Wind Turbine Model 3: Mass Parameter Adjustment and Positioning: 1. Weight Adjustment: Several counterweights are placed inside the platform body 31, and the floating wind turbine model 3 is weighed until the model weight matches the target weight. The counterweights are made of lead, which has high density and small volume, making it easy to adjust the weight accurately. A high-precision electronic scale is used for weighing, with a measurement accuracy of ±0.1kg. The weight adjustment deviation is controlled within ±1% to ensure that the model weight is consistent with the weight of the actual model after conversion according to the scale ratio, and to avoid distortion of dynamic characteristics caused by weight deviation.

[0048] 2. Model Placement: Place the counterweighted floating wind turbine model 3 on the bottom profile of the swing frame 1 frame 15. Adjust the position of the model to ensure that its longitudinal and transverse sections coincide with the longitudinal and transverse sections of the swing frame 1. The coincidence of the sections can ensure that the rotation center of the model is consistent with the rotation center of the swing frame, avoiding additional torque caused by eccentricity. During the placement process, use a level to calibrate the initial horizontal state of the model to ensure that the initial tilt angle is 0°, providing an accurate reference posture for the experiment.

[0049] 3. Adjustment of center of gravity position: Adjust the vertical distribution of the counterweights inside the platform body 31, and measure the center of gravity height of the floating wind turbine model 3 until the model's center of gravity height matches the target center of gravity height. The center of gravity height is measured using the suspension method. The center of gravity coordinates are calculated by measuring the balance position of the model at different suspension points. The measurement accuracy can reach ±1mm. The precise adjustment of the center of gravity position ensures that the model's stable center height is similar to that of the real model, avoiding distortion of the platform stability test results due to center of gravity deviation.

[0050] 4. Moment of inertia adjustment: Adjust the horizontal distribution of the counterweights inside the platform body 31, and measure the natural periods of the roll and pitch of the floating wind turbine model 3 through the swing frame 1 until the period matches the target period. The moment of inertia is indirectly measured through the natural period. The natural period is obtained by collecting attitude sensor data through the free swing of the swing frame. The moment of inertia is changed by adjusting the horizontal distribution of the counterweights so that the natural periods of the roll and pitch of the model are consistent with the period after the scale conversion of the real model, ensuring that the rotational dynamics characteristics of the model are similar to those of the real model.

[0051] 5. Model positioning: Horizontally rotate the floating wind turbine model 3 to the tilt direction required for the test. In this embodiment, the floating wind turbine model 3 will rotate around the OY axis. The model positioning uses an angle encoder to measure the rotation angle, and the positioning accuracy can reach ±0.1°. The initial tilt direction can be accurately set according to the test requirements to simulate the initial attitude of the floating wind turbine under different sea conditions, thereby improving the diversity and comprehensiveness of the test scenarios.

[0052] S5, Platform Static Water Stiffness Simulator 2: Installation and Stiffness Calibration: 1. In this embodiment, four platform hydrostatic stiffness simulators 2 are arranged symmetrically about the rotation axis OY. The top of each platform hydrostatic stiffness simulator 2 is connected to the bottom of the swing frame 1 frame 15, and the bottom is fixed vertically on the ground. During the installation process, it is ensured that the axis of the simulator is perpendicular to the ground to avoid stiffness measurement deviation caused by tilted installation. The symmetrical arrangement is ensured by measuring the spacing with a tape measure to ensure consistency. The connection point adopts a hinge method to allow the simulator to generate a certain rotation during deformation and avoid additional stress caused by rigid connection.

[0053] 2. The tension values ​​of the hydrostatic stiffness simulator 2 on the test platform under different rotation angles of the swing frame 1 were measured. The stress torque was further calculated based on the distribution of the hydrostatic stiffness simulators on the platform, resulting in a "rotation angle-torque" characteristic curve. This curve was designed to match the target hydrostatic stiffness of the floating wind turbine platform. The rotation angle was adjusted in steps, from -10° to +10°, with a 30-second pause at each 1° interval. Tension sensor data was collected, with a measurement accuracy of ±0.1N. Torque calculation was based on the product of the lever arm length and the tension. The lever arm length was precisely measured using a laser rangefinder. The slope of the "rotation angle-torque" characteristic curve represents the simulated stiffness. By comparing with the target stiffness, the number or model of simulators was adjusted to ensure that the stiffness simulation deviation was controlled within ±5%, providing an accurate hydrostatic stiffness environment for the experiment.

[0054] S6. Active Ballast System Load Adjustment Test: 1. Based on the required wind, wave, and current load history for the experiment, start the corresponding load simulator 38 speed dynamic control program to make the floating wind turbine model 3 produce the required tilt angle under the action of the horizontal thrust of the load simulator 38. After the load simulator is started, monitor the data of the six-component force sensor in real time to ensure that the thrust output meets the target history. At the same time, monitor the change of the model tilt angle through the attitude sensor to verify the correspondence between the load and the tilt angle, and provide benchmark data for subsequent load adjustment effect evaluation.

[0055] After the load simulator 38 runs stably, the active ballast control system program is started. Ballast water is transferred between different ballast tanks 4 according to the test requirements. The floating wind turbine model 3's motion attitude and the liquid level changes in each ballast tank 4 are recorded in real time during the test. After the active ballast control system is started, it analyzes the attitude data and liquid level data according to the preset control logic, generates pump and valve control commands, and adjusts the flow path and flow rate of ballast water in real time. The data recording frequency during the test is 100Hz. Key data such as attitude, liquid level, and pump and valve status are completely saved, which is convenient for subsequent control logic verification, load adjustment effect analysis and fault tracing. The robustness of the active ballast system can be verified by repeated tests. By changing parameters such as load history and initial tilt angle, system performance tests under different working conditions can be achieved, fully covering the operating scenarios that may be encountered in actual sea operations.

[0056] The above description is an explanation of the invention, not a limitation thereof. The scope of the invention is defined in the claims. Within the scope of protection of the invention, any form of modification may be made.

Claims

1. A land-based test device for a floating wind turbine active ballast system, characterized in that, include: A swing frame is used to support the floating wind turbine model and simulate its tilting motion. The platform hydrostatic stiffness simulator, connected to the swing frame, is used to generate a torque that resists the rotation of the floating wind turbine model, and to equivalently simulate the roll and pitch hydrostatic stiffness of the floating wind turbine platform in water. A floating wind turbine model, mounted on the swing frame, is used to simulate the structural and dynamic characteristics of a real floating wind turbine; Ballast water tank, located inside the floating wind turbine model, is used to store and allocate ballast water; The liquid level sensor is installed inside the conditioning water tank to collect real-time liquid level data. Pipelines, remote-controlled valves, and water pumps form the ballast water flow path, which is used to drive the transfer of ballast water between various ballast water tanks. The active ballast control system is electrically connected to attitude sensors, level sensors, remote control valves, and water pumps to formulate and execute load adjustment commands based on platform attitude and level data.

2. The onshore test device for the floating wind turbine active ballast system according to claim 1, characterized in that, The swing frame includes a base, support legs, a cutter head and cutter holder mechanism, a connector, and a frame. The frame is used to support the floating wind turbine model and is connected to the lower end of the cutter head and cutter holder mechanism through the connector. The upper end of the cutter head and cutter holder mechanism is connected to the support legs. The cutter head can rotate around the blade axis, thereby driving the frame and the floating wind turbine model to rotate, simulating the tilting motion of the platform.

3. The onshore test device for the floating wind turbine active ballast system according to claim 1, characterized in that, The platform hydrostatic stiffness simulator uses a spring assembly, the top of which is connected to the bottom of the swing frame, and the bottom is vertically fixed to the ground. Several simulators are arranged symmetrically about the rotation axis, and the resistance torque generated during deformation matches the target hydrostatic stiffness.

4. The onshore test device for the floating wind turbine active ballast system according to claim 1, characterized in that, The floating wind turbine model includes a platform body, a tower, six force sensors, and a load simulator. The platform body is equipped with attitude sensors to collect the platform's motion attitude. The load simulator generates thrust by driving a turbine with a motor to simulate the horizontal load of wind and waves on the floating wind turbine platform.

5. The onshore test apparatus for the floating wind turbine active ballast system according to claim 1, characterized in that, The ballast water tank is located inside the column of the floating wind turbine model and includes the tank body, top water inlet and bottom water outlet; the water outlet is connected to other ballast water tanks through pipes to realize ballast water allocation.

6. The onshore test apparatus for the floating wind turbine active ballast system according to claim 1, characterized in that, At least three liquid level sensors are arranged in each ballast tank, one of which is located at the centroid of the tank's cross-section, and the rest are evenly distributed along the circumference, for real-time feedback of the liquid level height in the tank.

7. A method for onshore testing of a floating wind turbine active ballast system, characterized in that, Using the testing apparatus according to any one of claims 1-6, the method includes the following steps: S1: Based on the Froude number similarity criterion, the actual wind, wave and current load time history is converted into the test target thrust time history. The load simulator "speed-thrust" characteristic curve is obtained through calibration, and a speed control program is written to reproduce the target thrust. S2: Assemble the floating wind turbine model, install the ballast tank, level sensor, remote control valve, water pump and active ballast control system, and complete the connection and pre-filling of ballast water channels; S3: Adjust the weight, center of gravity, and moment of inertia of the floating wind turbine model to the target values ​​by adding counterweights, and position the model in the tilt direction required for the test; S4: Install the platform hydrostatic stiffness simulator and perform stiffness calibration to ensure that the "angle-moment" characteristic curve matches the target hydrostatic stiffness; S5: Start the load simulator to simulate wind, wave and current loads, causing the floating wind turbine model to tilt. Then start the active ballast control system to perform load adjustment operations according to the preset logic, and complete the verification of control logic and system performance.

8. The onshore test method for the floating wind turbine active ballast system according to claim 7, characterized in that, In step S1, the wind, wave and current load history of the actual floating wind turbine is calculated by the integrated numerical analysis model of the floating wind turbine, and then converted into the test target thrust history according to the scaling ratio.

9. The onshore test method for the floating wind turbine active ballast system according to claim 7, characterized in that, In step S3, the height of the model's center of gravity is adjusted by adjusting the vertical distribution of the counterweights, and the rotational inertia of the model is adjusted by adjusting the horizontal distribution of the counterweights, until the natural periods of roll and pitch match the target values.

10. The onshore test method for the floating wind turbine active ballast system according to claim 7, characterized in that, In step S4, the tension value of the platform hydrostatic stiffness simulator under different swing frame rotation angles is tested, the stress moment is calculated, and the "rotation angle-torque" characteristic curve is obtained, which is then compared and corrected with the target hydrostatic stiffness.

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