How is the wind power measured

Wind power part 1: How does wind power actually work?

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Although the principle of wind power is simple, it is a complex technique to get the most out of the systems.

How is electricity generated from wind?

The wind causes the individual rotor blades on the wind turbines to rotate. This drives a generator that produces electricity. In physical terms, the kinetic energy of the air flow is converted into electrical energy.

Wind turbines are not a new invention. Who does not know the picturesque pictures of windmills? Even with the ancient Egyptians (approx. 4000 years ago) wind turbines were used as mills and pumping stations. In the last few centuries wind energy has also established itself in Europe; it was mainly used for grinding. Another application was the drainage of the dikes in the Netherlands.

In the middle of the 19th century there were 200,000 windmills in Europe. The term windmill, as we heard it over and over again in the first years of wind power, is of course no longer correct for today's wind turbines, because our power plants no longer grind.

From a variety of different construction methods have emerged Wind turbines in the early 1980s enforced with a horizontal axis of rotation, three rotor blades, gearbox and asynchronous generator. (the so-called "Danish concept")

Components

To put it simply, a wind turbine consists of a foundation, a tower, a nacelle and the rotor, which converts the flow energy of the wind into rotational energy. The towers of large turbines now reach a height of 120 m. As a rule of thumb, the higher the tower and the larger the rotor diameter, the more energy a wind turbine can deliver. The height of the tower is important because with increasing height there is a more uniform flow and higher wind speeds.

The flow of the wind creates a lift on the aerodynamically shaped rotor blades, which sets the rotor in rotation. The rotor drives an asynchronous generator connected directly to the power grid via a multi-stage gearbox. There are both systems with a specified constant speed (dependent on the mains frequency) and with variable speed.

The nacelle, which is mounted on the tower, can be rotated and contains all mechanical and electrotechnical components for converting the rotation of the rotor into electrical energy. The system is tracked in order to make the best possible use of the wind conditions; so it adapts to the wind direction.