Variable pitch and variable speed
Gamesa's wind turbines are equipped with a variable pitch technology. This technology allows for feathering the angle of the blades for each wind speed, whereby controlled extraction is made of the maximum energy in the wind flow. Thus, in below normal conditions the pitch is tailored to derive the maximum energy potential, and in above normal conditions the pitch is altered to derive a controlled amount of energy, so that the machine produces the rated power in a controlled and stable manner up to cut out wind speed. This system, besides maximising the wind energy derived, reduces the torque on the device and allows for the use of the full blade as an aerodynamic brake.
The generators in Gamesa wind turbines operate on the basis of variable rotation speed, providing stable generation at the grid frequency. This means that they perform as synchronous generators regarding the grid, but they allow for generation at varying speeds of rotation, whereby depending on the wind conditions the device's speed of rotation is the most appropriate for the maximum harnessing of wind energy. For variable rotation velocities of the generator the power control system is capable of generating electricity at the grid frequency (50 or 60 hz.). Only in this way is it possible to regulate the speed of rotation and derive maximum power from different wind conditions, operating under optimum aerodynamic conditions and controlling the torque affecting the equipment's various components.
In order to achieve this operation under conditions of varying speed, Gamesa equips its machines with doubly fed wound rotors. The supply frequency to the rotor is altered depending on the speed of mechanical rotation, using the most advanced technology for IGBTs.