|WIND||A wind farm or wind power installation comprises one or more wind turbines which transform the wind’s kinetic energy into electricity. The power of the wind turns a rotor with two or three blades connected to a d horizontal axis. Through a mechanical system which multiplies the number of revolutions, the rotation is then transferred to an electric generator. After being suitably transformed to a higher voltage level, the energy produced is released into the electric power grid.
Wind turbines are installed onto towers high enough to capture a greater amount of energy from the wind while avoiding turbulence created from the ground or obstacles.
A site’s wind characteristics are a critical factor which determines a wind power installation’s concrete feasibility. In fact, taking into consideration that the production of electricity for wind installations is proportional to three times the wind speed, small differences in a site’s anemometric characteristics can translate into in considerable differences in actual producible energy.
A generator, whether with a vertical or horizontal axis, requires a minimum wind (cut-in) speed of 3-5 m/s, providing power at a wind speed of 12-14 m/s. At high speeds (20-25 m/s, cut-off speed) wind turbines are blocked by the braking system for safety reasons.
Wind turbines can be subdivided into different power classes, depending on various dimensional specifications:
Medium and large sized wind turbines are mostly used in large installations known as wind farms, where they are connected to a mid to high voltage power grid.
The main components on a wind turbine are: