Wind turbine and associated control method
AssigneeEnvision Energy (Denmark) ApS
InventorsAnders Varming Rebsdorf, Michael Friedrich
Life of this patent
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Abstract
A method for controlling the position of blades of a two-bladed wind turbine when extreme conditions are detected or forecast for the wind turbine. When extreme conditions are detected or forecast, the wind turbine blades are positioned in a horizontal arrangement, and actively yawed such that a tip of one of the wind turbine blades points into the wind direction. The blades are yawed such as to actively follow the changing wind direction, resulting in a reduced surface area of the blades exposed to the extreme wind forces, due to the spear-like arrangement of the turbine blades. This reduced surface area provides for a reduction in the extreme loads which may be experienced by the wind turbine in such extreme wind conditions.
Claims12
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.
A wind turbine comprising
- a tower,
- a nacelle located at the top of said 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,
- a yaw system coupled to said nacelle,
- a wind direction detector positioned to detect wind direction at said turbine,
- a blade tip end direction detector for detecting the direction of a tip end of the blades,
- a wind speed detector at said wind turbine for detecting wind speed at said wind turbine, and
- a controller operable to:
- in the event of an extreme wind condition, cause said yaw system to actively yaw said nacelle and said rotor hub so as to place said rotor blades in a substantially horizontal alignment with the tip end of one of said rotor blades pointing into the wind to reduce the extreme wind loads experienced by the rotor blades based upon a wind direction detected at said turbine by said wind direction detector and a detected current direction of the tip end of said rotor blades detected by said blade tip end direction detector, when a difference between the detected tip end direction and said detected wind direction exceeds a threshold error margin value that is based on wind speed detected at said wind turbine by said wind speed detector.
Dependencies are inferred from the claim text.