Patent ID: 8803349

Claim:
A control method for reducing maximum loads experienced by a two-bladed wind turbine during extreme wind conditions, the wind turbine comprising a tower, a nacelle located at the top of the tower, a rotor hub rotatably mounted at said nacelle, a generator coupled to said rotor hub via a shaft, a pair of wind turbine blades of at least 35 meters length provided on said rotor hub, and a yaw system coupled to said nacelle, the method comprising the steps of: in the event of an extreme wind condition, placing said rotor blades in a substantially horizontal alignment; aligning said rotor blades such that a tip end of one of said rotor blades faces into the wind to reduce the extreme wind loads experienced by the rotor blades, wherein said step of aligning comprises actively yawing said nacelle and said rotor hub by actuating said yaw system; detecting the wind direction at said turbine, and wherein said step of aligning is based on said detected wind direction; detecting the current direction of said tip end of said rotor blades, and wherein said step of aligning is performed when the difference between the detected tip end direction and said detected wind direction exceeds a threshold error margin value; and detecting the current wind speed at the turbine, wherein said threshold error margin value is selected based on the detected wind speed at said wind turbine.