Sliding variable-pitch resistance pneumatic brake structure of lift-drag composite vertical axis wind turbine

Abstract

The invention discloses a sliding variable-pitch resistance pneumatic brake structure of a lift-drag composite vertical axis wind turbine, comprising: an end plate, the end plate comprising a first fixed plate and a second fixed plate, the first fixed plate and the second fixed plate being arranged at an interval; the guide rail piece is fixed on the end plate, the guide rail piece comprises a first guide rail rod and a second guide rail rod, the first guide rail rod is fixed on the first fixing plate, and the second guide rail rod is fixed on the second fixing plate; a plurality of resistance type blades are movably arranged on the guide rail piece, and the resistance type blades are located on the guide rail piece through a lead screw sliding block assembly to move; one end of the first guide rail rod is fixedly connected with a first driving motor, and one end of the second guide rail rod is fixedly connected with a second driving motor; and the displacement control feedback assembly is in electric signal connection with a first driving motor and a second driving motor. According to the structure, rapid braking is achieved, and the safety and reliability under the extreme wind condition are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbines, and in particular to a sliding variable pitch resistance aerodynamic brake structure of a lift-drag composite vertical axis wind turbine. Background Art

[0002] Vertical axis wind turbines (VAWTs) have garnered widespread attention in recent years for their compact structure, wind direction independence, and low noise performance in distributed energy systems, urban environments, and off-grid power supply scenarios. However, their inherent aerodynamic characteristics make them susceptible to speed loss, dynamic stall, and mechanical overload in wind speeds exceeding rated limits, necessitating the development of efficient and reliable braking technologies. While conventional braking solutions are primarily focused on horizontal axis wind turbines (HAWTs), the axially symmetric nature and complex three-dimensional flow structure of VAWTs present unique challenges for braking systems.

[0003] The braking technology of vertical axis wind turbines has long been the focus of academia and industry. Existing braking solutions mainly include three categories: mechanical friction braking, electromagnetic eddy current braking and pneumatic brakes. Among them, mechanical braking (such as disc brakes) relies on physical contact friction, and has problems of response delay (typical delay time > 2s) and short wear life. Although electromagnetic eddy current braking can achieve non-contact deceleration, its energy consumption is high (accounting for 5%-10% of the rated power) and it is prone to failure in high humidity environments. In comparison, pneumatic brakes achieve energy dissipation by changing the aerodynamic characteristics of the blades, and have the advantages of fast response and no mechanical loss, but its design needs to take into account both braking efficiency and aerodynamic stability.

[0004] In the field of aerodynamic braking, existing technologies mainly focus on two types of solutions. 1) Passive deflector braking: Fixed-angle deflectors reduce the rotational speed by increasing the drag area. However, its static geometric design leads to significant parasitic drag at low wind speeds (efficiency loss of up to 15%), and it is easy to induce blade flutter under high-speed conditions. When the wind speed exceeds 25m / s, traditional deflector braking takes 8-10 seconds to reduce the rotational speed to a safe threshold, and is accompanied by a large vibration amplitude, which significantly shortens the bearing life. 2) Blade yaw braking: The angle of attack is changed by adjusting the overall yaw angle of the blade, such as the active variable pitch system reported in the journal "Renewable Energy". However, this method requires extremely high precision of the drive mechanism, and the sudden change of the lift component during yaw may cause torque oscillation, exacerbating structural fatigue.

[0005] These drawbacks severely restrict the feasibility of vertical-axis wind turbines in typhoon-prone areas. Therefore, a new brake structure is urgently needed that can sense the flow field state in real time, dynamically adjust aerodynamic parameters, and achieve coordinated optimization of lift and drag torque. Summary of the Invention

[0006] In response to the shortcomings of the prior art, the present invention aims to provide a sliding variable-pitch drag aerodynamic brake structure for a lift-drag hybrid vertical-axis wind turbine, addressing the low braking efficiency, dynamic response hysteresis, and structural complexity of conventional vertical-axis wind turbines. To achieve the above-mentioned and other advantages of the present invention, a sliding variable-pitch drag aerodynamic brake structure for a lift-drag hybrid vertical-axis wind turbine is provided, comprising:

[0007] An end plate, the end plate comprising a first fixing plate and a second fixing plate, wherein the first fixing plate and the second fixing plate are spaced apart from each other;

[0008] A guide rail member, the guide rail member is fixed to the end plate, and the guide rail member includes a first guide rail rod and a second guide rail rod, the first guide rail rod is fixed to the first fixing plate, and the second guide rail rod is fixed to the second fixing plate;

[0009] The guide rail member is provided with a plurality of resistance-type blades which are movable and are moved on the guide rail member by a lead screw slider assembly;

[0010] One end of the first guide rail is fixedly connected to a first drive motor, and one end of the second guide rail is fixedly connected to a second drive motor;

[0011] A displacement control feedback component is electrically connected to the first drive motor and the second drive motor.

[0012] Preferably, the guide rail member is fixedly connected to a bottom bearing assembly, the bottom bearing assembly is fixedly connected to a power generation assembly, and the power generation assembly is connected to an electrical and control assembly.

[0013] Preferably, an ultrasonic anemometer is fixedly connected to the displacement control feedback component, and the ultrasonic anemometer is used to monitor the wind speed in real time and transmit the signal to the displacement control feedback component. The displacement control feedback component realizes the precise sliding of the resistance-type blade according to the preset mapping relationship between the sliding displacement and the wind speed, thereby adjusting the aerodynamic characteristics of the wind turbine to achieve the purpose of pneumatic braking.

[0014] Preferably, the lift-type blades are fixedly connected to the bottom bearing assembly, and are transmission-connected to the power generation assembly.

[0015] Compared with existing technologies, this invention offers the following advantages: by adjusting the radial position of the drag blades, the effective frontal area of ​​the blades is altered, leveraging the nonlinear coupling effect of lift and drag to generate a reverse aerodynamic torque, achieving rapid braking. The aerodynamic brake structure includes: designing a sliding drag blade and its drive system; and optimizing the matching relationship between sliding parameters and aerodynamic performance through numerical simulation. This invention addresses the limited adjustment freedom and complex structure of traditional mechanical brake structures, significantly improving safety and reliability in extreme wind conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the layout and structure of the wind wheel of the sliding variable pitch drag aerodynamic brake structure of the lift-drag composite vertical axis wind turbine according to the present invention;

[0017] Figure 2 Schematic diagram of the sliding pitch-variable aerodynamic brake structure of the lift-drag composite vertical axis wind turbine according to the present invention;

[0018] Figure 3 The figure is a schematic diagram of the pneumatic brake structure-drag type blade movement of the sliding variable pitch drag aerodynamic brake structure of the lift-drag composite vertical axis wind turbine according to the present invention. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] Reference Figure 1 A sliding variable-pitch drag aerodynamic brake structure for a lift-drag composite vertical axis wind turbine, comprising:

[0021] The end plate 1 includes a first fixing plate and a second fixing plate, wherein the first fixing plate and the second fixing plate are spaced apart from each other; the end plate 1 serves as a top support.

[0022] The guide rail member 9 is fixed to the end plate 1 and comprises a first guide rod and a second guide rod. The first guide rod is fixed to the first fixed plate, and the second guide rod is fixed to the second fixed plate. The guide rail member 9 is coated with polytetrafluoroethylene (PTFE) and has a coefficient of friction of less than 0.03. Combined with the planetary roller screw, the displacement accuracy is controlled to ±1mm. The low friction coefficient of the PTFE coating ensures low energy consumption and high precision during the sliding of the resistance-type blade 3. The planetary roller screw provides high load capacity and transmission accuracy, ensuring the stability and reliability of the sliding of the resistance-type blade 3.

[0023] The guide rail member 9 is movably provided with a plurality of drag blades 3, which are positioned on the guide rail member 9 for movement via the lead screw slider assembly 2. Lift blades 5 are fixedly connected to the bottom bearing assembly 8 and are transmission-connected to the power generation assembly 6 to convert torque into electrical energy. The lift blades 5 and the drag blades 3 are coaxially connected and, under the action of wind, respectively generate lift and drag, which together influence the aerodynamic characteristics of the wind turbine. The lift blades 5 primarily drive the rotor by generating lift, while the drag blades 3 change drag by adjusting their position, thereby regulating the rotor speed or achieving braking.

[0024] The lift-type blades 5 utilize a NACA 0018 symmetrical airfoil with a chord length of 1.25m, a rotor diameter of 27m, and a span length of 44m. This airfoil has a symmetrical structure, providing stable lift characteristics and suitable for wind turbine operation in varying wind directions. The upper sliding resistance blades 3 have a diameter of 4m and slide along the blade span via guide rails 9, the first drive motor, and the second drive motor. The sliding range is -100% to 100% of the lift-type rotor radius. The resistance blades 3 are designed to adjust their position according to changes in wind speed, thereby changing the aerodynamic characteristics of the wind turbine and achieving an aerodynamic braking function.

[0025] One end of the first guide rail is fixedly connected to a first drive motor, and one end of the second guide rail is fixedly connected to a second drive motor;

[0026] The displacement control feedback component 11 is electrically connected to the first drive motor and the second drive motor.

[0027] Furthermore, the guide rail member 9 is fixedly connected to a bottom bearing assembly 8, which is in turn fixedly connected to a generator assembly 6, which is connected to an electrical and control assembly 7. The electrical and control assembly 7 connects the first and second drive motors and the generator assembly 6, controlling the operation of the device and the output of electrical energy. The bottom bearing assembly 8 is mounted on the bottom support for rotation.

[0028] Furthermore, an ultrasonic anemometer 10 is fixedly connected to the displacement control feedback component 11. The ultrasonic anemometer 10 is used to monitor the wind speed in real time and transmit the signal to the displacement control feedback component 11. The displacement control feedback component 11 realizes the precise sliding of the resistance type blades according to the preset mapping relationship between the sliding displacement and the wind speed, thereby adjusting the aerodynamic characteristics of the wind turbine to achieve the purpose of aerodynamic braking. The ultrasonic anemometer 10 has a sampling rate of 20 Hz and can monitor the wind speed changes in real time and transmit the wind speed signal to the displacement control feedback component 11. The photoelectric encoder is used to provide displacement feedback of the resistance type blades 3 to ensure the precise control of the sliding displacement of the resistance type blades 3. The MEMS accelerometer is used to monitor the vibration of the wind turbine and provide vibration signals to the intelligent control unit so that the control strategy can be adjusted in time under sudden changes in wind speed or other abnormal conditions.

[0029] Furthermore, a fuzzy adaptive algorithm is employed, and acceleration feedback feedforward control is introduced for dynamic compensation, effectively suppressing overshoot caused by sudden changes in wind speed, keeping the overshoot to less than 3%. This algorithm dynamically adjusts the sliding displacement of the drag blades 3 based on real-time wind speed, rotational speed, and vibration signals, optimizing the wind turbine's aerodynamic performance and ensuring stable operation and efficient power generation under varying wind speed conditions.

[0030] Furthermore, under different wind speed conditions, the ultrasonic anemometer 10 monitors the wind speed in real time and transmits the signal to the displacement control feedback component 11. The displacement control feedback component 11 controls the sliding variable pitch drive system based on the preset mapping relationship between sliding displacement and wind speed, achieving precise sliding of the resistance-type blades 3, thereby adjusting the aerodynamic characteristics of the wind turbine and achieving the purpose of aerodynamic braking. The control sliding variable pitch drive system is composed of the ultrasonic anemometer 10 and the displacement control feedback component 11, ensuring the stable operation of the wind turbine under different wind speeds. The specific mapping relationship is as follows:

[0031]

[0032] Dynamic compensation: Introducing acceleration feedback feedforward control to suppress overshoot caused by sudden changes in wind speed (overshoot < 3%)

[0033] In actual operation, the wind turbine automatically switches operating modes according to different wind speeds:

[0034] Low wind speed mode (≤2m / s): The resistance-type blades slide outward to their maximum position, with the sliding displacement S=R, increasing the aerodynamic resistance and maintaining stable operation of the wind turbine.

[0035] Medium wind speed mode (2-12 m / s): The resistance blades gradually retract according to a preset formula based on wind speed changes, with the sliding displacement S = 0.1R + 0.09R (12-U) to balance the speed and ensure power generation efficiency. For example, at wind speed U = 6 m / s, the sliding displacement S = 0.1R + 0.09R (12-6) = 0.1R + 0.54R = 0.64R.

[0036] High wind speed mode (12-20m / s): The sliding displacement of the resistance-type blade is maintained at S=0.1R, and stable power generation is achieved.

[0037] Ultra-high wind speed mode (20-25m / s): The blades gradually retract to their limit position, and the sliding displacement of the resistance blades gradually decreases, with the sliding displacement S = 0.1R - 0.22R (U - 20). For example, when the wind speed U = 22.5m / s, the sliding displacement S = 0.1R - 0.22R (22.5-20) = 0.1R - 0.55R = -0.45R, triggering the pneumatic brake to protect the equipment.

[0038] Extremely high wind speed mode (U>25m / s): The sliding displacement of the resistance-type blade is S=-R, and it is fully retracted to the extreme position to achieve the maximum aerodynamic braking effect and ensure equipment safety.

[0039] The number of devices and processing scales described herein are intended to simplify the description of the present invention, and the application, modification, and variation of the present invention will be apparent to those skilled in the art. Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiment. They can be applied to various fields suitable for the present invention. For those skilled in the art, additional modifications can be easily implemented. Therefore, the present invention is not limited to the specific details and illustrations shown and described herein without departing from the general concept defined by the claims and their equivalents.

Claims

1. A sliding variable pitch drag aerodynamic brake structure for a lift-drag composite vertical axis wind turbine, characterized in that: include: An end plate (1), the end plate (1) comprising a first fixing plate and a second fixing plate, the first fixing plate and the second fixing plate being spaced apart; A guide rail member (9), wherein the guide rail member (9) is fixed on the end plate (1), and the guide rail member (9) comprises a first guide rail rod and a second guide rail rod, wherein the first guide rail rod is fixed on the first fixing plate, and the second guide rail rod is fixed on the second fixing plate; A plurality of resistance-type blades (3) are movably provided on the guide rail member (9), and the resistance-type blades (3) are moved on the guide rail member (9) via the lead screw slider assembly (2); One end of the first guide rail is fixedly connected to a first drive motor, and one end of the second guide rail is fixedly connected to a second drive motor; A displacement control feedback component (11) is electrically connected to a first drive motor and a second drive motor.

2. The sliding variable pitch drag aerodynamic brake structure of a lift-drag composite vertical axis wind turbine according to claim 1, characterized in that: The guide rail member (9) is fixedly connected to a bottom bearing assembly (8), the bottom bearing assembly (8) is fixedly connected to a power generation assembly (6), and the power generation assembly (6) is connected to an electrical and control assembly (7).

3. The sliding variable pitch drag aerodynamic brake structure of a lift-drag composite vertical axis wind turbine according to claim 2, characterized in that: An ultrasonic anemometer (10) is fixedly connected to the displacement control feedback component (11). The ultrasonic anemometer (10) is used to monitor the wind speed in real time and transmit the signal to the displacement control feedback component (11). The displacement control feedback component (11) realizes the precise sliding of the resistance-type blade according to a preset mapping relationship between sliding displacement and wind speed, thereby adjusting the aerodynamic characteristics of the wind turbine and achieving the purpose of pneumatic braking.

4. The sliding variable pitch drag aerodynamic brake structure of a lift-drag composite vertical axis wind turbine according to claim 1, characterized in that: A lift-type blade (5) is fixedly connected to a bottom bearing assembly (8), and the lift-type blade (5) is transmission-connected to a power generation assembly (6).

Images