Patent ID: 7800243

Claim:
A variable rotational speed wind turbine comprising a wind turbine rotor comprising one or more blades, a doubly-fed induction generator coupled to the wind turbine rotor, a rotor current controller arranged to control currents of a rotor of the generator, compensation means having computation means, and means for providing input to the compensation means, the input being representative of at least an instantaneous angular speed of the rotor of the generator, wherein the computation means is arranged to compute an instantaneous compensation control output in dependency of said instantaneous angular speed of the rotor of the generator and feed the compensation control output to the rotor of the generator, the computation means being arranged to compute said compensation control output during operation of the wind turbine to compensate at least partly for dependencies on the rotor angular speed of the locations of poles of a generator transfer function, thus making a resulting generator transfer function substantially independent of variations in the rotor angular speed during operation of the wind turbine.