Method and system for determining an alignment correction function

1. A method for determining a correction function for a wind turbine, by means of which a windward wind speed can be determined on the basis of a leeward wind speed measured by a leeward-side anemometer of the wind turbine, windward and leeward relating to a rotor of the wind turbine, comprising:

measuring a measured windward wind speed, a measured leeward wind speed, and a measured leeward wind direction, whereby a multiplicity of measurement values is recorded for each of the measured windward wind speed, the measured leeward wind speed, and the measured leeward wind direction in a defined time period; and

determining the correction function on the basis of the recorded measurement values by means of a model, the recorded measurement values being related to each other in the model, and the correction function assigning an inferred windward wind speed to a given leeward wind speed in dependence on a given leeward wind direction; and

outputting the determined correction function.

2. The method according to claim 1 , the model being a multilinear regression model.

3. The method according to claim 1 , wherein the correction function is further determined on a basis of a compensation calculation.

4. The method according to claim 3 , wherein the correction function is determined on a basis of a regression analysis.

5. The method according to claim 1 , the measured windward wind speed being determined by means of a sensor device.

6. The method according to claim 5 , wherein the sensor device is arranged on the windward side and separately from the wind turbine.

7. The method according to claim 6 , wherein the sensor device is arranged on an adjacent wind turbine.

8. The method according to claim 5 , wherein the sensor device is configured as a Lidar instrument, a Sodar instrument, or a reference anemometer.

9. A method for determining an alignment correction function for a nacelle of a wind turbine that is arranged on a tower, the wind turbine having at least one anemometer arranged on a leeward side of a rotor of the wind turbine and a wind vane arranged on the leeward side of the rotor, the method comprising:

determining a correction function for the wind turbine, by means of which a windward wind speed can be determined on the basis of a leeward wind speed measured by the at least one anemometer arranged on the leeward side of the rotor of the wind turbine, windward and leeward relating to the rotor of the wind turbine, wherein determining the correction function for the wind turbine comprises:

measuring a measured windward wind speed, a measured leeward wind speed, and a measured leeward wind direction, whereby a multiplicity of measurement values is recorded for each of the measured windward wind speed, the measured leeward wind speed, and the measured leeward wind direction in a defined time period; and

determining the correction function on a basis of the recorded multiplicity of measurement values by means of a model, the recorded multiplicity of measurement values being related to each other in the model, and the correction function assigning an inferred windward wind speed to a given leeward wind speed in dependence on a given leeward wind direction;

measuring a power measure of the wind turbine, a further leeward wind direction by means of the wind vane, and a further leeward wind speed by means of the at least one anemometer, wherein a second multiplicity of measurement values are recorded for each of the power measure of the wind turbine, the further leeward wind direction, and the further leeward wind speed over a second defined time period;

assigning the second multiplicity of measurement values of the power measure and of the further leeward wind direction to the second multiplicity of measurement values of the further leeward wind speed that are grouped into at least one wind-speed bin on a basis of instants at which the second multiplicity of measurement values were recorded, the second multiplicity of measurement values of the further leeward wind speed being corrected by means of the correction function;

determining a model function for a relationship between the power measure and the further leeward wind direction for the at least one wind-speed bin;

determining the alignment correction function for a target alignment of the nacelle relative to the measured further leeward wind direction on a basis of the model function, the alignment correction function fulfilling a predefined criterion in respect of the determined model function for the at least one wind-speed bin; and

outputting the determined alignment correction function.

10. The method according to claim 9 , the criterion being a maximization of the model function.

11. The method according to claim 9 , the power measure being a rotor rotational speed of the rotor or a generator rotational speed of a generator of the wind turbine.

12. The method according to claim 9 , the model function being determined for a plurality of wind-speed bins, and the output alignment correction function forming an operating characteristic for the target alignment of the nacelle relative to the measured further leeward wind direction.

13. The method according to claim 9 , further comprising a method for operating the wind turbine, the method for operating the wind turbine comprising:

determining a current leeward wind speed by means of the at least one anemometer; and

aligning the nacelle by use of the alignment correction function, and taking into account the determined current leeward wind speed.

14. The method according to claim 13 , wherein the alignment correction function comprises an operating characteristic.

15. A computer program, which comprises instructions that, when they are executed by a computer, cause the computer to execute a method according to claim 1 .

16. A computer-readable medium, on which a computer program according to claim 15 is stored.

17. A system for determining an alignment correction function for a nacelle of a wind turbine that is arranged on a tower and has at least one anemometer, a wind vane, and a control facility, the at least one anemometer and the wind vane arranged on a leeward side of a rotor of the wind turbine, and the control facility configured to:

record a second multiplicity of measurement values of a further leeward wind speed determined by the at least one anemometer, of a further leeward wind direction determined by the wind vane, and of a power measure of the wind turbine, over a second defined time period;

assign the second multiplicity of measurement values of the power measure and of the further leeward wind direction to the second multiplicity of measurement values of the further leeward wind speed that are grouped into at least one wind-speed bin, on a basis of instants at which the second multiplicity of measurement values were recorded, the second multiplicity of measurement values of the further leeward wind speed being corrected by the correction function determined according to a method according to claim 1 ;

determine a model function for a relationship between the power measure and the further leeward wind direction for the at least one wind-speed bin;

determine the alignment correction function for a target alignment of the nacelle relative to the measured further leeward wind direction on a basis of the model function, the alignment correction function fulfilling a predefined criterion in respect of the determined model function for the at least one wind-speed bin; and

output the determined alignment correction function via an interface.