A method for reducing blade vibrations in a wind turbine

A method for controlling a wind turbine, the wind turbine comprising a tower, a nacelle mounted on the tower, a hub mounted rotatably on the nacelle, and three or more wind turbine blades, each wind turbine blade extending between a root end connected to the hub via a pitch mechanism, and a tip end, the wind turbine blades defining a rotor plane, the wind turbine further comprising blade connecting wires, each blade connecting wire extending between a connection point on one wind turbine blade and a connection point on a neighbouring wind turbine blade, and pre-tension wires, each pre-tension wire being connected to one of the blade connecting wires and to a pre-tension adjustment mechanism, the method comprising:

• measuring at least one parameter of the wind turbine blades of the wind turbine,
• deriving, from the at least one measured parameter, an estimate for blade vibrations within the rotor plane of each wind turbine blade and/or coupled rotor vibrations originating from the wind turbine blades, and
• controlling the pre-tension adjustment mechanism based on the estimated vibrations in order to counteract the blade vibrations and/or coupled rotor vibrations.