Patent ID: 7928593
Filing Date: 2011-04-19
Classification: F03D,F05B,Y02E

Abstract:
1. A method for damping oscillations in a wind turbine comprising a wind turbine tower, a nacelle arranged on top of the wind turbine tower, and a number of rotor blades rotatably connected to the nacelle, the oscillations being generated by forces induced on the nacelle and the wind turbine tower by the rotating rotor blades, the method comprising: providing an internally suspended pendulum mass structure being operationally connected to an upper tower section; providing a platform being fixedly attached to the upper tower section; and providing a plurality of stacked, mutually displaceable friction plates being displaceably arranged relative to the platform, the plurality of stacked, mutually displaceable friction plates being adapted to be displaced relative to the platform in response to relative movements between the suspended pendulum mass structure and the platform in order to dissipate energy from the suspended pendulum mass structure by friction.