WORLD WIND ENERGY NET

From wind to electricity
Wind turbines use energy from the wind in order to generate electricity. They do this with their blades, which capture the wind and turn. When there is no wind, the blades will remain at a 45-degree angle so that the turbine can draw maximum energy from gentle winds. Turbines begin to produce energy when wind speeds reach about four meters per second. The blade gradually rotates towards an angle of 0 degrees with the broad surface facing the wind. When the wind strikes the blade, it creates positive pressure on the front of it and negative pressure behind it. In other words, the wind pushes against the front edge and creates a suction effect behind the blade, which makes the rotor turn. At maximum rotational speed, the blade tips reach a speed of 250 km an hour.

Connecting to the grid
The generator is connected via the turbine’s electrical control system. The electrical output is lead through a high-voltage transformer to the grid, which supplies people with electricity. In just 2-3 hours, a V90-3.0 MW turbine can produce enough power to cover the annual electricity consumption of an average European household.

Output regulation
There are three ways of regulating output: 1) Passive stall, where turbines operate at a fixed rotational speed with non-adjustable blades. 2) Active stall, where turbines operate at a fixed rotational speed with adjustable blades. 3) Pitch, where turbines operate either at a constant rotational speed or with variable speed. The leading edge of the blade is turned into the wind to reduce uplift.  The turbine stops when the wind exceeds 25 metres per second, since wind speeds above this level place too much strain on turbine components.