Patent ID: 8186949

Claim:
A method for damping tower vibrations in a floating wind turbine installation, the installation comprising a floating cell, a tower arranged over the floating cell, a generator mounted on the tower that is rotatable in relation to the wind direction and fitted with a wind turbine comprising turbine blades, and an anchor line arrangement that is connectable to anchors or foundations on a sea bed; wherein the method comprises: controlling the generator in response to changes in relative wind velocity against the tower, by controlling the blade angle of the turbine blades by means of a controller in the constant power or RPM range of the wind turbine; and damping the tower's eigenvibrations, ω eig , by, in addition to controlling the controller in the constant power or RPM range of the wind turbine, an increment, Δβ, being added to the blade angle of the turbine blades on the basis of the tower velocities, ΔŻ, so that the eigenvibrations of the tower are counteracted.