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 power.
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 to be able to supply it to the electrical network.
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 into the grid.
The useful life of the wind turbines that are currently installed is close to 25 years.
What does the aerogenerator do?
The operation of a wind turbine is based on a series of cleverly designed steps that converge to harness the power of the wind and convert it into electricity.
First, the wind turbine blades are aerodynamically designed to capture the momentum of the wind as it blows. The wind crashes against them, generating a force that makes them spin. This rotating movement is transmitted to the rotor, which is connected to a main shaft located at the heart of the wind turbine.
This main axis becomes the focal point of energy transformation. As the blades turn and the rotor moves, the kinetic energy of the wind is channeled into a gearbox. In this step, the gearbox performs an ingenious mechanical feat: it transforms the slow but powerful movement of the rotor into a fast and lower force movement in the generation shaft.
This generating shaft connected to the gearbox, in turn, is linked to an electrical generator. The generator contains magnets and coils of wire that interact in amazing ways to generate alternating electrical current (AC). This newly created electrical current is the tangible product of the kinetic energy of the wind.
Types of wind turbines
There are two types of wind turbines depending on the position of the rotor axis:
-
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 ground rotating horizontal axis wind generator is formed by 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 wind energy into mechanical energy.
-
A gearbox to change the ratio of angular speed and power in order to have optimal values for the operation of the electric generator. However, some wind turbines use other techniques to perform this operation.
-
The electric generator driven by the rotor that is the one that transforms mechanical energy into electricity.
This type of wind turbine can generate a highly variable power, which can range from a few kW to 5-6 MW, depending on the local wind and weather conditions.
Traditional wind turbines have, almost without exception, the axis of rotation horizontal.
The blades of this type of wind turbines 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 high resistance to strong gusts of wind and the ability to take advantage of any direction of the wind 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 in 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 on the blades during rotation. This variation causes great fatigue and risk of breakage.
Maximum and minimum operating speed
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 rotate. When the speed reaches 12 to 14 m/s, it can already 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 blocking can be done with brakes that block the rotor or by turning the blades to modify the aerodynamics so that the wind cannot propel them.