Patent ID: 8878376

Claim:
A wind turbine comprising: a wind turbine tower with an upper end and a lower end, which lower end is provided on a wind turbine foundation; a wind turbine nacelle provided at the upper end of said tower; a hub provided at said nacelle; at least two wind turbine rotor blades each with a mounting end and a free end, which mounting end is mounted on the hub for rotation in a rotational plane around an axis that is extended by shaft coupled to a generator or a gearbox; grid connection for feeding produced electricity from the generator to a grid, which grid connection has voltage detection means for detecting changes in the voltage on the grid; at least two masses each placed between the mounting end and the free end of each rotor blade, wherein said wind turbine rotor blades each has a blade weight and a blade length of at least 35 meters between the mounting end and the free end, where each mass is between 10% and 40% of blade weight of each rotor blade; where the rotor blade has an inner blade section and an outer blade section separated by a pitching system, that is located between the mounting end and the free end and configured to pitch the outer blade section relative to the inner blade section, where a weight and radial extend of one of the masses are formed by at least the weight and radial extend of the pitching system.