A wind turbine is a windmill that converts the kinetic energy of the wind into a rotating motion to generate electricity. These wind turbines are an essential element for the generation of wind energy.
Wind energy is a renewable energy source that produces electrical energy thanks to the force of the wind. Wind turbines are designed in an aerodynamic way to convert the force of the wind into mechanical energy and later into electricity in an alternator.
Wind farms are made up of several wind turbines. The purpose of wind farms is the production of electrical energy in order to supply it to the electrical grid.
The frequency fed to the network connection must be constant at 50 Hz in Europe and 60 Hz in America. The electricity produced is sent to a series of converters before feeding the power to the grid.
The useful life of the wind turbines that are currently installed is close to 25 years.
Types of Wind Turbines
There are two types of wind turbines according to the position of the rotor shaft:
Horizontal axis wind turbines: in which the rotor is oriented, actively or passively, parallel to the direction of origin of the wind.
Vertical axis wind turbines: whose orientation is independent of the direction of origin of the wind.
Horizontal Axis Wind Generator
A wind generator with a horizontal axis of rotation on the ground is made up of a steel tower with heights between 60 and 100 meters. At the top of the tower there is a gondola where the most important elements of the machine are located:
The blades that capture the energy of the wind. The blades are between 20 and 60 meters long.
The rotor converts the energy of the wind into mechanical energy.
A gearbox to change the angular speed and power ratio in order to have optimal values for the operation of the electric generator. However, some wind turbines use other techniques to do this.
The electric generator driven by the rotor that is the one that transforms mechanical energy into electricity.
This type of wind turbine can generate highly variable power, which can range from a few kW to 5-6 MW, depending on the local wind and the weather.
Traditional wind turbines have, almost without exception, the horizontal axis of rotation.
The blades of this type of wind turbine are made of wood or polyester or epoxy reinforced with fiberglass.
Vertical Axis Wind Generator
This type of windmill is characterized by having fewer moving parts in its structure. This simplicity gives it a high resistance to strong gusts of wind and the ability to take advantage of any wind direction without having to constantly orient yourself.
Vertical axis wind turbines are very versatile machines. These machines can be used both for domestic use and for centralized production of electricity on the order of megawatts. A single turbine meets the electrical needs of about 1,000 homes on average.
The substantial difference compared to horizontal axis turbines is the strong torque variation in the blades during rotation. This variation causes great fatigue and risk of breakage.
What Is the Maximum and Minimum Speed at Which a Wind Turbine Can Operate?
The range of wind speeds is in a median of 4 to 22 m / s.
All wind turbines require a minimum wind speed (cut) of 3 to 5 m / s to turn. When the speed reaches 12 to 14 m / s it can deliver electrical power.
On the other hand, with very strong winds 20–25 m / s, the braking system blocks the wind turbine for safety reasons. The lock can be done with brakes that lock the rotor or by turning the blades to modify the aerodynamics so the wind cannot push them.