Method and apparatus for adjusting a yaw angle of a wind turbine
A method and an apparatus for adjusting a yaw angle of a wind turbine comprising a rotor having a plurality of rotor blades and a hub are provided. The method is adapted for adjusting the yaw angle from an actual yaw angle to a desired yaw angle and comprises the steps of measuring a wind direction at the location of the wind turbine, measuring the yaw angle of the wind turbine and/or determining a wind direction relative to the nacelle orientation, calculating a pitch angle of at least one rotor blade as a function of the measured wind direction and the measured yaw angle and/or the wind direction relative to the nacelle orientation, and adjusting the pitch angle of the rotor blades according to the calculated pitch angle such that a yaw momentum is generated for changing the yaw angle from the actual yaw angle to the desired yaw angle.
1. A method for adjusting a yaw angle of a wind turbine from an actual yaw angle to a desired yaw angle, the wind turbine comprising a rotor comprising a plurality of rotor blades attached to a hub, the method comprising:
measuring a wind direction at a location of the wind turbine;
measuring a yaw angle of the wind turbine;
calculating a set signal for a yaw angle modification as a function of the measured wind direction and the measured yaw angle;
measuring a yaw momentum of the wind turbine;
calculating a pitch angle of the rotor blades as a function of the set signal and the measured yaw momentum; and
adjusting the pitch angle of the rotor blades according to the calculated pitch angle such that a yaw momentum is generated for changing the yaw angle from the actual yaw angle to the desired yaw angle.
2. The method in accordance with claim 1 , wherein the step of calculating the set signal for the yaw angle modification is based on the determination of an angle difference between the measured wind direction and the measured yaw angle of the wind turbine or a measured relative wind direction at a nacelle of the wind turbine.
3. The method in accordance with claim 1 , wherein the step of calculating the set signal for the yaw angle modification and the step of calculating the pitch angle of the rotor blades as a function of the set signal and the measured yaw momentum is performed by means of one single processing unit.
4. The method in accordance with claim 1 , wherein the adjustment of the pitch angle of each rotor blade is dependent on a rotational position of the each rotor blade.
5. The method in accordance with claim 1 , wherein the adjustment of the pitch angle of the plurality of rotor blades is performed independently for each rotor blade.
6. The method in accordance with claim 1 , wherein the adjustment of the pitch angle of the plurality of rotor blades is performed with respect to an incoming wind direction measured by a wind direction sensor.
7. The method in accordance with claim 1 , wherein the change of the yaw angle is supported by driving at least one yaw motor and at least one yaw brake of the wind turbine.
8. The method in accordance with claim 1 , wherein a yaw momentum of the wind turbine is compensated by the adjustment of the pitch angle of at least one of the plurality of rotor blades.
9. A wind turbine comprising a rotor comprising a plurality of rotor blades attached to a hub, said wind turbine further comprising:
a sensor device configured to measure a wind direction at a location of the wind turbine;
a first processing unit configured to calculate a set signal for a yaw angle modification from an actual yaw angle to a desired yaw angle as a function of the measured wind direction and at least one of the actual yaw angle and a wind direction relative to a nacelle orientation of the wind turbine;
a second processing unit configured to calculate a pitch angle control signal for a pitch adjustment as a function of the set signal and a measured actual yaw momentum; and
an actuator device configured to adjust a pitch angle of at least one of the plurality of rotor blades as a function of the pitch angle control signal such that a yaw momentum is generated for changing the yaw angle from the actual yaw angle to the desired yaw angle.
10. The wind turbine in accordance with claim 9 , wherein the sensor device comprises a yaw angle sensor for measuring the actual yaw angle.
11. The wind turbine in accordance with claim 10 , wherein the sensor device further comprises a yaw momentum sensor for providing the measured actual yaw momentum.
12. The wind turbine in accordance with claim 9 , further comprising a pitch control unit configured to supply a pitch angle driver signal as a function of the control signal for the actuator device in order to control the pitch angle of the rotor blades.
13. The wind turbine in accordance with claim 11 , wherein the actuator device comprises a yaw angle adjustment unit for adjusting the yaw angle in cooperation with the actual yaw momentum.