Wind turbines can be broadly divided into the following important components: Center support, fixed blade auxiliary support, rotor hub, blade, gear transmission, etc. In the world, wind turbines are generally divided into two categories: It is a horizontal axis wind turbine, and it is a vertical axis wind turbine.
First, the advantages of vertical axis wind turbines
1. The overall performance index is high. In the construction, the double vane design of straight blades and triangles is used, and the main force points are concentrated on the hub, solving problems such as blade shedding, breakage and blade flying out. The vertical axis wind turbine blades are pressed. The same angle difference forms a circle, so that the purpose of the design can reduce the pressure on the center support; in addition, a series of auxiliary equipment such as a gear box, a reduction gear box, and a transmission device can be placed on a work platform relatively close to the ground, which reduces the The weight of the fan itself reduces the construction and maintenance costs of the fan to some extent, and the vertical axis fan can be used in building integration, which is conducive to urban construction.
2. To reduce noise pollution. The use of horizontal plane rotation and blade application aircraft wing principle design, making the noise reduced to the extent measured under the natural environment.
3. It is not necessary to install auxiliary systems. Compared with the horizontal axis fan, the vertical axis fan's blade rotation plane is parallel to the ground, so that the wind energy can be obtained from all directions, and does not need to be increased like the horizontal axis fan. The navigation device to adjust the direction of receiving wind energy, the overall structure becomes more simple, to a certain extent, reduce the vibration generated by the operation of the fan, and enhance its reliability.
4. Strong wind resistance. The principle of horizontal rotation and triangular double fulcrum design makes it vulnerable to wind pressure and can withstand typhoons of 45 meters per second.
5. The blade structure is simple. As the vertical axis fan blade enhances the capture of wind energy, when the blade is rotated by the wind, only the pressure of the fan and the centrifugal force of the rotary centrifugal force are applied to the blade. Therefore, the degree of requirement for the blade material is reduced, and the selected material is more The universal, reduces the cost of purchasing the blade.
6. The rotational speed range becomes larger. Compared with the horizontal axis fan, the vertical axis wind turbine can reach much higher maximum rotational speed than the horizontal axis fan, and the running stability under strong wind speed is better than that of the horizontal axis fan. Can withstand 60m / s high-intensity wind speed. As long as the control strategy and the fan itself material selection is appropriate, the use of vertical axis fan wind energy is much greater than the horizontal axis fan.
At the same time, the vertical axis wind turbine has the following disadvantages: First, the vertical axis fan's starting performance index is worse than that of the horizontal axis fan, and the second is that the blade rotates one week, producing negative torque at some positions, resulting in low fan output efficiency; third, all The common problems of wind turbines are: anti-vibration problems, especially the vibration problems of large-scale wind turbines; and fourthly, wind is an uncertain real-time change factor, and the stability of wind power output power is not as good as traditional thermal power generation. Fluctuations are not easy to connect to the net.
Second, the improvement of vertical axis wind turbine
Building a vertical axis wind turbine platform requires two aspects of software design and hardware design. In the hardware design, it mainly includes the overall structure design of the fan, the material selection of the parts, the dimension design of each part of the structure, etc. Mainly in software design Including the aerodynamic analysis of the vertical axis fan, the large control strategy for the fan, and the development of the control software. The two aspects of the hardware and software design are independent and connected. Each aspect is based on other aspects. On the basis of the final combination of software and hardware, a unified system is formed. Since the development and application of software are complex and cumbersome in the research, there are not many introductions here. The following mainly introduces the hardware requirements that have a significant influence on the vertical axis wind turbine in the hardware design. For the development and use of vertical axis fans, it is not only necessary to conduct in-depth research on control strategies, but also on the fan's hardware conditions can not be ignored. The ultimate goal is to make the fan in various conditions for optimal design of all aspects of the fan , Make the fan can make better use of wind energy, ensure the output power of the fan The highest efficiency, and for the fan itself, to make increase its service life, easier to maintain, construction and maintenance of the finished product more in line with the economy.
For the selection of the number of fan blades, one depends on the output power that the fan wants to reach in the original design; the second is the need to consider the cooperation between the gearbox of the blade and the fan; and the third is to consider the noise of the fan to the environment. Pollution; fourth is to consider the construction and maintenance costs of the fan. Today, most common H-axis fans are mostly 4-blade, 6-blade and 8-blade fans.
The number of blades affects the overall performance of the fan to a certain extent. Regardless of the material composition and size of the fan blades, comparing a two-bladed fan with a three-bladed fan, the output power of the two blades is similar, but the two-bladed fan can have a high The tip speed ratio, when the wind speed is too large, the two-blade winder is more practical than the three-blade fan.
The number of blades of the wind wheel has a certain influence on the load of the wind turbine. When the number of blades is large, the noise of the fan will increase, and the vibration of the wind wheel will also increase. The hard-axis index is added to the compressive and seismic conditions of the machine hardware. However, from the appearance Considering that the three-blade fan is more acceptable to the public due to its symmetry and other reasons.
After the two-bladed fan has reduced the number of blades, the cost of constructing the fan and the maintenance cost will be reduced accordingly, but there are also some unfavorable factors. Therefore, the choice of the number of fan blades depends on the specific circumstances, and the purpose of constructing the fan is determined. For example, home fans, large-scale fan networks and experimental fans for teaching, the number of blades of these fans is uncertain.
Third, speed control
When the fan reaches the rated power, the fan speed at this time is called the rated speed of the fan. The rated speed is an important scalar, especially in the variable pitch fan, the control system controls the change of the pitch angle, the purpose is mainly The fan is controlled within the rated speed range to ensure that the output power of the fan is always under the rated power, so that the output power of the fan is stable, and the stable value is the minimum difference between the fan and the ideal value of the maximum use of wind energy. Pitch control The ultimate goal is to keep the fan running at this optimal rated speed.
The tip speed ratio affects the overall performance of the fan's hardware during the overall operation of the fan. When the wind speed is constant, the high tip speed ratio indicates that the fan speed is fast at this time, and the speed is faster, indicating that more wind energy is received. It is the fast rotation speed that can make the blade produce a larger rising buoyancy, to a certain extent, reduce the weight of the wind wheel bracket to the spindle, which is beneficial to the service life of the fan. Therefore, when designing the fan, the fan will have a larger tip speed. In addition, the higher tip speed ratio reduces the requirements on the blade material and reduces the cost of constructing the fan. However, if the tip speed ratio is too high, it will cause some problems: For example, it will cause Noise pollution is not conducive to people's lives. Secondly, it will cause fan vibration problems. If resonance occurs, it will directly threaten the service life of the fan. If the fan is applied in the city, it will even threaten human life. Therefore, the fan Tip speed ratio to choose the right value.
