What is a WIND TURBINE and how does generate electricity? Wind power - Components - Accidents

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Wind turbines are devices that convert the wind's kinetic energy into electrical energy.

We can simply describe the wind as moving air, caused by differences in atmospheric pressure between different regions of our planet.
Differences in atmospheric pressure arise as a result of temperature differences.
When the air moves from an high pressure region into a low-pressure region, we feel the moving air as wind.

On the other hand, we can describe wind energy as the process in which wind is used to generate mechanical energy or electricity.

Since the beginnings of civilization man has always took advantage of wind energy: from the simple sail boats, to the grinding grain with the windmills, up to the actual production of electricity thanks to the wind energy converters, also known as WIND TURBINES.

There are different types and different sizes of wind turbines.
In this video we will focus on the most common horizontal axis turbines:
-We'll find out which are the main components of this particular type of wind turbine
-We will understand how these devices are able to transform wind energy into electric current.
-We’ll see why don’t wind turbines have more than 3 blades, through the observation of their airfoil shape.
-And we will also see what are the main causes of accidents that can occur during the operation of these devices.

The first wind turbines were built towards the end of the nineteenth century with the aim of supplying electricity to small isolated villages

In the following years, the gradual structural and technological improvements of these devices, allowed the creation of real wind farms entirely dedicated to the production of electricity

Nowadays there are about 26 companies in the world specialized in the production of wind turbines

As we already mentioned at the beginning of this video, wind turbines transform mechanical energy into electrical energy. The wind energy caught by the wind turbines is in fact transferred thanks to a mechanical shaft to a generator.

The generator transforms the rotation energy into electrical energy, which in turn is transferred to a transformer, usually placed at the base of the wind tower. The transformer acts as a link between wind turbines and distribution grid. It steps up the low output voltage from the generator to higher distribution voltage level.


Let's take a look at the various components of a wind turbine:

This is the TOWER, one of the most important parts. It represents the supporting structure of the wind turbine and has the function of absorbing the vibrations generated by the rotary motion of the blades.

These are the BLADES which are aerodynamically optimized to capture the maximum power from the wind and transfer it to the rotor hub. Each blade is usually 20 m or more in length, depending on the power level.

The ROTOR is the rotating part of the wind turbine. The rotor hub holds the wind turbine blades while connected to the gearbox via the low-speed shaft. Here we can find the pitch control system. Thanks to the pitch control, blades are turned in their longitudinal axis to change the angle of attack according to the wind directions. This mechanism also blocks the rotation of the rotor when the wind is too strong, or too weak.

The NACELLE is instead the enclosure of the wind turbine that houses all of the generating components, including: the gear box, the braking system and the generator, but also the pitch control system and the yaw system, which is responsible for the orientation of the wind turbine rotor towards the wind.

An anemometer places at the rear of the nacelle, in fact, constantly detects the wind direction. Whenever there’s a change in wind direction, the anenometer sends a signal to the yaw system, that provides to rotate the entire nacelle and consequently the rotor and the blades , to meet the wind at the best angle.

But now let's see in detail what happens when the wind turbine goes into action:
The blades starts to turn when the wind reaches the so called “cut-in wind speed”, that is the point at which the turbine starts generating electricity from turning.

The rotor is connected to the drive shaft, which rotates inside the necelle.
The rotational energy of the drive shaft is transformed into electrical energy by the generator.
A generator is in fact a device that uses electromagnetic induction to produce electrical voltage...