Stratosphere regional residence resistance type vertical axis power generation system and application method thereof

Abstract

The application discloses a stratosphere area residence resistance type vertical axis power generation system and an application method thereof, and relates to the field of power generation. The system comprises a high altitude balloon, a fixed length connecting rope, an adjustable connecting rope, a connecting rope adjusting device and a resistance type vertical axis wind turbine. The high altitude balloon is connected with the fixed length connecting rope through a flange plate. The fixed length connecting rope suspends the connecting rope adjusting device. The upper end of the adjustable connecting rope is connected with a roller of the connecting rope adjusting device. The resistance type vertical axis wind turbine is suspended through the adjustable connecting rope. The application combines the function of a floatation device with the resistance type vertical axis wind turbine to form a double floatation device system. The high altitude balloon is connected with a high altitude wind power generation device through the connecting rope. The east-west direction aerodynamic forces of the two are in opposite directions and are offset to each other, so that the area residence is realized and the working height of the resistance type vertical axis wind turbine is effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of high-altitude airship technology, and particularly relates to a stratospheric region dwell drag type vertical axis power generation system and its application method. Background Technology

[0002] With the continuous deterioration of the environment, countries around the world have begun to focus on the new energy industry, and wind power, as an important renewable resource, is a crucial direction for the development of renewable energy globally. Wind turbines are classified into vertical axis wind turbines and horizontal axis wind turbines according to the direction of their rotation axis. Vertical axis wind turbines are not constrained by wind direction, relying on wind resistance for rotation, and do not require the gearboxes necessary for horizontal axis wind turbines. They have advantages such as simple structure, low starting speed, low noise, and low cost. Currently, the main factor restricting the development of vertical axis wind turbines is their low wind energy utilization efficiency, requiring a large supply of wind energy to compensate. Compared to traditional low-altitude wind power generation, high-altitude wind power generation has advantages such as high capacity coefficient and low generation cost. Furthermore, the abundant wind energy at high altitudes can significantly improve the operating performance of vertical axis wind turbines. Therefore, vertical axis high-altitude wind power generation has enormous development potential.

[0003] As a common type of aircraft that relies on atmospheric buoyancy to take off, aerostats operate at altitudes far higher than current wind power generation facilities. At these altitudes, wind speeds and energy levels are significantly increased, effectively improving the output efficiency of wind power generation equipment. Furthermore, by leveraging the characteristic that wind direction reverses significantly at different altitudes in the east-west direction of the stratosphere, aerostats can remain stationary in the east-west direction of the stratosphere.

[0004] The following research has been conducted on control strategies for drag-type vertical axis wind turbines and dual-aircraft systems:

[0005] (1) Drag-type vertical axis wind turbine

[0006] Hand Brain et al. used numerical simulation to analyze various parameters affecting wind turbines, identified the advantages and disadvantages of each influencing factor, and proposed a baseline wind turbine design method based on the analysis of these advantages and disadvantages, which further promoted the development of wind turbines.

[0007] Akwa et al. considered the influence of Reynolds number on numerical simulation results and established a continuity equation applicable to low Reynolds numbers. Through research on the overlap ratio of wind turbines, they found that the continuity equation can be applied to this type of numerical simulation research. When the overlap ratio reaches 15%, the drag rotor has the best aerodynamic performance, and the average power coefficient of the best performance is 0.3161.

[0008] Li Yusheng et al. studied the transient flow field of a 5-bladed drag-type vertical axis wind turbine. They conducted numerical simulations and analyses on factors such as the size of the computational domain and the outlet boundary, investigated the influence of the rotor position on the turbine's output power, and optimized the blade width. The turbine achieved maximum power with a blade width of 800 mm, at which point the rotor's wind energy utilization efficiency was 24.3%.

[0009] (2) Control strategy for dual airship system

[0010] Deng Xiaolong et al. from the National University of Defense Technology studied the trajectory design of a new type of stratospheric airship that utilizes wind fields. They designed independent control area dwell strategies in the east-west and north-south directions, as well as a cooperative control area dwell strategy based on the comprehensive utilization of wind fields. The north-south flight control is achieved by providing thrust through the power propulsion system.

[0011] In patent CN 110244754 B, Chen Li et al. proposed a control system and method for stationary hovering of stratospheric airships. Through a PID tracking algorithm, the vector thrust coincidence module is controlled to resist wind field effects and achieve stationary hovering. However, this strategy still relies on an active propulsion system, placing extremely high demands on energy, propulsion, and control systems, thus limiting its application in the airship field.

[0012] Du Huafei et al. from Beijing University of Aeronautics and Astronautics developed an effective method to utilize winds from different directions by changing the balloon's floating altitude. They also established a mathematical model to simulate the flight performance and dwell time of a stratospheric ultra-high-pressure balloon in a real wind field. The results show that the balloon's altitude fluctuates within a diurnal cycle as its volume changes. By utilizing the variations in wind conditions at different altitudes, the horizontal displacement of the balloon can be greatly reduced, enabling the balloon to remain in a region for extended periods.

[0013] The above studies have the following problems / deficiencies:

[0014] (1) For drag-type vertical axis wind turbines

[0015] Drag-type vertical axis wind turbines generally suffer from high starting wind speeds and poor wind energy capture capabilities. Furthermore, under low wind speed conditions, drag-type vertical axis wind turbines often stop generating electricity due to insufficient starting torque. The standard NACA0012 airfoil drag-type vertical axis wind turbine with four blades has a power coefficient of only 0.19 and is prone to dynamic stall due to pressure differences.

[0016] (2) Regarding high-altitude wind power generation technology

[0017] Currently, existing flight platforms carrying high-altitude generators require ground base stations for tethering and control. The flight altitude is severely limited by the length of the tether. An excessively long tether can make the overall attitude of the flight platform difficult to control, while an excessively short tether will greatly limit the generator's power output. Furthermore, the tether often serves the purpose of power transmission and has its own weight; an excessively long tether increases the load, making it difficult to further increase the flight altitude. Summary of the Invention

[0018] The purpose of this invention is to provide a stratospheric region dwell resistance type vertical axis power generation system and its application method that can solve the above-mentioned defects.

[0019] The stratospheric region stationary drag-type vertical axis power generation system provided by the present invention includes a high-altitude balloon, a fixed-length connecting rope, an adjustable connecting rope, a connecting rope adjustment device, and a drag-type vertical axis wind turbine. The high-altitude balloon is connected to the fixed-length connecting rope through a flange. The fixed-length connecting rope suspends the connecting rope adjustment device. The upper end of the adjustable connecting rope is connected to the roller of the connecting rope adjustment device. The drag-type vertical axis wind turbine is suspended by the adjustable connecting rope.

[0020] In one embodiment of the above system, the drag-type vertical axis wind turbine includes a main airbag, wind turbine blades, an auxiliary airbag, a main support, a Magnus starter rotor, and a wind power generation system; the outer wall of the main airbag is provided with wind turbine blades and the wind power generation system is fixed thereon; the auxiliary airbag is provided with a compressor and an air vent, and is built into the main airbag; the main airbag has main supports at both ends of the main shaft, and the main supports are respectively equipped with Magnus starter rotors.

[0021] In one embodiment of the above system, the main airbag is based on the Darrieux wind turbine and its shape is a biomimetic simulation of the nautilus.

[0022] In one embodiment of the above system, the wind turbine blades are obtained by rotating a Fibonacci spiral around a central axis 6-12 times within a range of 180°.

[0023] In one embodiment of the above system, the wind power generation system includes a speed increaser, a generator, an off-grid controller, a digital inverter, a battery pack, a motor, and a gearbox. The speed increaser, generator, off-grid controller, digital inverter, and battery pack are fixed to a bracket on the same axis but opposite in direction to the auxiliary airbag in the main airbag by bolt connections, and the connecting wires are attached to the wall of the main airbag. The motor and its driven gearbox are respectively installed on the fixed brackets at both ends of the main airbag, so that the gear at the output shaft end of the gearbox meshes with the Magnus rotor.

[0024] In one embodiment of the above system, a rigid coupling is used to connect the generator shaft to the output shaft of the speed increaser and the motor shaft to the input shaft of the speed reducer, ensuring that the gears at both ends mesh and that the current in the wires flows smoothly.

[0025] The altitude control strategy of the above-mentioned system provided by this invention, during flight near the stratosphere, involves activating the compressor of the auxiliary airbag to draw in outside air, increasing the overall mass of the system and decreasing its overall flight altitude; conversely, opening the vent on the auxiliary airbag releases the air to the outside, reducing the overall mass of the system and increasing its overall flight altitude. Without changing the air content in the auxiliary airbag, extending the connecting rope simultaneously increases the altitude of the high-altitude balloon and decreases the altitude of the drag-type vertical axis wind turbine; conversely, shortening the connecting rope decreases the altitude of the high-altitude balloon and increases the altitude of the drag-type vertical axis wind turbine.

[0026] The east-west wind field cancellation strategy provided by this invention, when the entire drag-type vertical axis wind turbine is located within the stratospheric region, executes the wind field cancellation strategy of the dual-aircraft system. At this time, real-time wind field data near the stratospheric region is obtained by satellite. Based on the wind speed and direction at different altitudes, the height at which the resultant force on the high-altitude balloon and the drag-type vertical axis wind turbine is minimized is calculated and set as the target working height. By adjusting the overall mass of the system and the linkage control of the change in the length of the connecting rope, the system reaches a balanced state. At this time, the resultant force on the system is minimized, and the system is stationed in the target region.

[0027] This invention proposes a wind turbine blade with a Fibonacci spiral shape, and adds a Magnus starter rotor to the main shaft of the wind turbine to assist in starting. It also combines the features of a dual-aerostat system, significantly increasing wind speed and energy efficiency in the operating area, effectively overcoming the common shortcomings of high starting speed and low wind energy utilization in vertical axis wind turbines. Connecting the high-altitude balloon and the drag-type vertical axis wind turbine with a connecting rope to form a dual-aerostat system effectively increases the operating altitude of the power generation equipment. Simultaneously, by adjusting the inflation and deflation of air in the auxiliary airbag on the wind turbine and the rope retraction and deployment mechanism on the high-altitude wind power generation platform, the operating altitude of each part of the system is adjusted to regulate the force balance in the east-west direction. In short, this invention combines the function of an aerostat with a drag-type vertical axis wind turbine to form a dual-aerostat system. The high-altitude balloon is connected to the high-altitude wind power generation equipment via a connecting rope. The east-west aerodynamic forces acting on both are opposite and cancel each other out, achieving both regional dwell time and effectively increasing the operating altitude of the drag-type vertical axis wind turbine. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the system structure according to an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram of the drag-type vertical axis wind turbine in this embodiment (wind turbine blades are not shown).

[0030] Figure 3 This is a schematic diagram of the rotor cross-section structure of the drag-type vertical axis wind turbine in this embodiment.

[0031] Figure 4 This is a schematic diagram of the power generation system configuration in this embodiment.

[0032] Figure 5 This is a schematic diagram showing the state of the Magnus starter rotor after installation in this embodiment.

[0033] Figure 6 This is a schematic diagram of the cross-section under stress after the Magnus starter rotor is installed in this embodiment.

[0034] Figure 7a and Figure 7b This is a schematic diagram of the overall flight altitude adjustment process of the system in this embodiment.

[0035] Figure 8 This is a schematic diagram of the adjusted system equilibrium state. Detailed Implementation

[0036] like Figure 1 As shown, the stratospheric region stationary drag-type vertical axis power generation system disclosed in this embodiment includes a high-altitude balloon 1, a fixed-length connecting rope 2, a connecting rope adjustment device 3, an adjustable connecting rope 4, and a drag-type vertical axis wind turbine 5.

[0037] The high-altitude balloon 1 includes a balloon bag 11 and a flange 12 connected to it. The connecting rope adjustment device 3 is suspended by a fixed-length connecting rope 2 connected to the flange.

[0038] The connecting rope adjustment device 3 adopts an existing structure including a motor, a reducer, a battery pack, and a drum, which will not be described in detail here.

[0039] The upper end of the adjustable connecting rope 4 is fixed to the drum of the connecting rope adjusting device 3, and the lower end suspends the drag-type vertical axis wind turbine 5.

[0040] like Figure 2 As shown, the drag-type vertical axis wind turbine 5 includes a main support 51, a main airbag 52, a Magnus starter rotor 53, a secondary airbag 54, and a wind power generation system 55.

[0041] The main airbag 52 is based on the Darrieux wind turbine and is a Fibonacci spiral structure designed based on the biomimetic simulation of the nautilus.

[0042] like Figure 3The cross-sectional diagram of the wind turbine shown illustrates that the airflow channel formed by the turbine blades is obtained by rotating a Fibonacci spiral around the central axis eight times within a 180° range. This airflow channel design increases the windward area while reducing the drag on the leeward side and the turbine. Simultaneously, the leeward blades extend into the interior of the windward blades, providing acceleration and guidance, thus driving the turbine to rotate with less wind force and improving wind energy conversion efficiency.

[0043] The main airbag 52 has a built-in auxiliary airbag 54, which is equipped with an air compressor and has a vent.

[0044] The main airbag 52 is fixed to the main support 51 at both ends, and the lower end of the adjustable connecting rope 4 is fixed to the main support 51. The Magnus starter rotor 53 is fixed to the main support 51.

[0045] like Figure 4 As shown, the wind power generation system 55 includes a speed increaser 551, a generator 552, an off-grid controller 553, a digital inverter 554, a battery pack 555, a motor 556, a gearbox 557, as well as wires, switches, etc.

[0046] The speed increaser 551, generator 552, off-grid controller 553, digital inverter 554, and battery pack 555 are fixed to a bracket on the same axis but opposite in direction to the auxiliary airbag 54 within the main airbag 52 using bolts, with the wires flush against the wall of the main airbag 52. Simultaneously, the motor 556 and gearbox 557 are fixed to the brackets at both ends of the main airbag 52, ensuring that the gear on the output shaft of the gearbox 557 meshes with the Magnus rotor 53. Rigid couplings are used to connect the shaft of the generator 552 to the output shaft of the speed increaser 551, and the shaft of the motor 556 to the input shaft of the gearbox 557, ensuring gear meshing at both ends and unobstructed current flow in the wires.

[0047] As shown in Figure 5, the Magnus starter rotor 53 is installed and outputs torque after being powered by the motor 556. The torque is transmitted through the meshing of the gear set to drive the two Magnus rotors 53 on the same axis to rotate clockwise and counterclockwise respectively. The tangential force generated by the Magnus effect drives the rotation of the main airbag 52, which can effectively solve the problem of high start-up wind speed of the drag-type vertical axis wind turbine 5.

[0048] Figure 6This is a cross-sectional force diagram of the Magnus starter rotor 53 after installation. When there is a westerly wind, the rotors at the rear on the horizontal axis are blocked by the rotors in front, and the tangential forces generated by the Magnus effect decrease sequentially (i.e., F1 > F2 > F3 > F4). The rotors on the vertical axis generate only axial forces, therefore the torque on the entire Magnus starter rotor 53 is clockwise. When starting the drag-type vertical axis wind turbine 5, due to the high required starting wind speed, the wind turbine has difficulty quickly reaching its rated operating speed. Therefore, the motor is energized to accelerate the rotation of the main airbag 52. After the main airbag 52 is successfully started, the power is disconnected, and the Magnus rotor 53 is shut down.

[0049] The altitude control strategy for the dual airships in this embodiment is as follows:

[0050] like Figure 7a As shown, during flight near the stratosphere, starting the compressor can draw outside air into the auxiliary airbag 54, increasing the overall mass of the system and thus reducing the overall flight altitude. Conversely, opening the vent on the auxiliary airbag 54 to release the air to the outside will reduce the overall mass of the system and thus increase the overall flight altitude.

[0051] like Figure 7b As shown, one end of the connecting rope 4 is fixedly connected to the roller in the connecting rope adjusting device 3, and the other end is welded to the main support 51 of the drag-type vertical axis wind turbine 5. By rotating the roller in the connecting rope adjusting device 3, the distance between the high-altitude balloon and the high-altitude wind power generation platform can be changed by adjusting the length of the connecting rope 4. Without changing the air content in the auxiliary airbag 54, extending the connecting rope 4 can simultaneously raise the height of the high-altitude balloon 1 and lower the height of the drag-type vertical axis wind turbine 5; conversely, shortening the connecting rope 4 will lower the height of the high-altitude balloon 1 and raise the height of the drag-type vertical axis wind turbine 5. Through the linkage control of adjusting the overall mass of the system and the change in the length of the connecting rope 4, the heights of the high-altitude balloon 1 and the drag-type vertical axis wind turbine 5 can be arbitrarily adjusted within a certain range, thereby reaching any target height.

[0052] The east-west wind field offsetting strategy in this embodiment is as follows:

[0053] When the entire drag-type vertical axis wind turbine system is located within the stratospheric region, a wind field cancellation strategy is implemented using the dual-aircraft system. Real-time wind field data near the stratospheric region is obtained via satellite. Based on wind speed and direction at different altitudes, the altitude at which the resultant force on the high-altitude balloon 1 and the drag-type vertical axis wind turbine 5 is minimized is calculated and set as the target operating altitude. Through coordinated control adjusting the overall mass of the system and the length of the connecting rope 4, the system achieves the desired operating height. Figure 8The equilibrium state shown indicates that the net force on the system is minimal, enabling the system to remain in the target region.

[0054] Once the system rises to the working area near the stratospheric zero wind zone and is ready to operate, the switch is first closed to supply current to the motor 556. Through gear meshing in the reduction gearbox 557, the torque is transmitted to the Magnus starter rotor 53. The tangential force generated by the Magnus effect drives the rotation of the main airbag 52, gradually accelerating it. At the same time, the torque generated by the main shaft is input to the speed increaser 551 through gear meshing. When the main airbag 52 reaches the working speed, the switch is disconnected to shut off the Magnus starter rotor 53. The speed increaser 551 increases the rotational speed of the drive shaft through internal gear transmission and transmits it from the high-speed shaft to the generator 552. The generator 552 generates current by cutting magnetic lines of force through the rotation of the shaft, and outputs it from the terminal block. The off-grid controller 553 can detect the DC voltage and output current of the main circuit, calculate the output power of the wind turbine, and achieve maximum power point tracking. After tracking and processing by the off-grid controller 553, the current is introduced into the battery pack 555 through wires and stored. The digital inverter 554 is a converter that can convert the DC power output from the battery pack 555 into AC power with fixed frequency and voltage or frequency and voltage regulation. After conversion by the digital inverter 554, the power generated by the power generation system can be connected to the grid or used to connect to loads.

[0055] In summary, this invention proposes a regionally stationary dual-aerostat system, aiming to solve the regional stationary problem of wind power generation equipment operating in the stratosphere, thus resolving the issue of fixed overall platform position. Furthermore, it addresses the problem of insufficient wind power required for the start-up of drag-type vertical-axis wind turbines, while leveraging the significant reversal of wind direction at different altitudes in the east-west direction near the stratosphere to achieve aerostat stationary in the east-west direction of the stratosphere. Based on research into the shape of a nautilus shell, biomimetic simulations were conducted to propose a wind turbine blade with a Fibonacci spiral shape. The entire turbine rotates around a horizontal axis, increasing the windward area and reducing drag on the leeward side and the turbine itself. Simultaneously, the leeward blades extend into the windward blades, providing acceleration and guidance, driving the turbine rotation with relatively low wind force, improving wind energy conversion efficiency, and enhancing power generation efficiency. Furthermore, a Magnus rotor is added to the shaft to further reduce the turbine's start-up wind speed, enabling the turbine to quickly reach operating speed.

Claims

1. A stratospheric region-drag type vertical axis power generation system, characterized in that: The system includes a high-altitude balloon, a fixed-length connecting rope, an adjustable connecting rope, a connecting rope adjustment device, and a drag-type vertical axis wind turbine. The high-altitude balloon is connected to the fixed-length connecting rope via a flange. The fixed-length connecting rope suspends the connecting rope adjustment device. The upper end of the adjustable connecting rope is connected to the drum of the connecting rope adjustment device. The drag-type vertical axis wind turbine is suspended by the adjustable connecting rope. The drag-type vertical axis wind turbine includes a main airbag, wind turbine blades, auxiliary airbag, main support, Magnus starter rotor, and wind power generation system; The main airbag is based on the Darrieux wind turbine and is a Fibonacci spiral structure obtained by biomimetic simulation of the nautilus. The wind turbine blades are obtained by rotating a Fibonacci spiral around a central axis 6-12 times within a range of 180°, with the leeward blades extending into the interior of the windward blades. The auxiliary airbag is equipped with an air compressor and a deflation port, and is built into the main airbag; Main supports are installed at both ends of the main shaft of the main airbag, and Magnus starter rotors are installed on the main supports respectively. The outer wall of the main airbag is equipped with wind turbine blades, and the wind turbine as a whole rotates around a horizontal axis; The wind power generation system is fixed to the outer wall of the main airbag; The wind power generation system includes a speed increaser, generator, off-grid controller, digital inverter, battery pack, motor, and gearbox. The speed increaser, generator, off-grid controller, digital inverter, and battery pack are fixed to the main support on the same axis but opposite directions in the main airbag by bolts, and the connecting wires are attached to the wall of the main airbag. The motor and its driven gearbox are installed on the main support at both ends of the main airbag, so that the gear at the output shaft end of the gearbox meshes with the Magnus starter rotor. The tangential force generated by the Magnus effect drives the main airbag to rotate.

2. The stratospheric region stationary drag type vertical axis power generation system as described in claim 1, characterized in that: A rigid coupling is used to connect the generator shaft to the output shaft of the speed increaser and the motor shaft to the input shaft of the speed reducer, ensuring that the gears at both ends mesh and that the current flows smoothly through the wires.

3. A height control method for the system according to any one of claims 1-2, characterized in that: During flight near the stratosphere, the compressor of the auxiliary gasbag is activated to draw in outside air into the auxiliary gasbag, increasing the overall mass of the system and decreasing the overall flight altitude; conversely, the vent on the auxiliary gasbag is opened to release the air into the outside, reducing the overall mass of the system and increasing the overall flight altitude. Without changing the air content in the auxiliary airbag, extending the connecting rope can simultaneously increase the height of the high-altitude balloon and decrease the height of the drag-type vertical axis wind turbine; conversely, shortening the connecting rope will decrease the height of the high-altitude balloon and increase the height of the drag-type vertical axis wind turbine.

4. A method for counteracting the east-west wind field effect of the system according to any one of claims 1-2, characterized in that: When the entire drag-type vertical axis wind turbine is located within the stratospheric region, a wind field countermeasure strategy is implemented using the dual-aircraft system. At this time, real-time wind field data near the stratospheric region is obtained via satellite. Based on the wind speed and direction at different altitudes, the altitude at which the resultant force on the high-altitude balloon and the drag-type vertical axis wind turbine is minimized is calculated and set as the target working altitude. By adjusting the overall mass of the system and the linkage control of the change in the length of the connecting rope, the system reaches a balanced state. At this point, the resultant force on the system is minimized, and the system is able to remain in the target region.

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