Method and arrangement for continuous calibration of a wind direction measurement

A method for performing a wind direction measurement for a wind turbine, the method comprising:

• measuring plural samples of a relative wind direction representing a difference angle between a real wind direction and an orientation of a measurement equipment, to obtain plural measured relative wind directions, wherein the orientation is a direction orthogonal to a rotor blade plane;
• deriving a measured relative wind direction change based on the measured relative wind directions;
• measuring plural samples of a performance parameter indicating a performance of the wind turbine;
• deriving a performance change based on the plural samples of the performance parameter;
• determining a correlation value between the measured relative wind direction change and the performance change, wherein the correlation value is a mean correlation value averaged over all reasonable wind speeds;
• measuring further plural samples of the relative wind direction;
• and
• correcting the measured relative wind directions based on a single averaged correlation value, such that the correlation value approaches closer to zero;
• wherein an effective wind speed is estimated using a turbine model, taking into account at least one of actual power produced, actual rotor speed, and actual pitch angle and wherein the performance parameter comprises the effective wind speed.

A method for performing a wind direction measurement for a wind turbine, the method comprising:

• measuring plural samples of a relative wind direction representing a difference angle between a real wind direction and an orientation of a measurement equipment, to obtain plural measured relative wind directions, wherein the orientation is a direction orthogonal to a rotor blade plane;
• deriving a measured relative wind direction change based on the measured relative wind directions;
• measuring plural samples of a performance parameter indicating a performance of the wind turbine;
• deriving a performance change based on the plural samples of the performance parameter;
• determining a correlation value between the measured relative wind direction change and the performance change including performing an operation that results in a scaled estimation of the correlation between the measured relative wind direction change and the change in the performance parameter, wherein the correlation value is a mean correlation value averaged over all reasonable wind speeds;
• measuring further plural samples of the relative wind direction;
• and
• correcting the further measured relative wind directions based on the correlation value, such that the correlation value approaches closer to zero;
• correcting the further measured relative wind directions based on a single averaged correlation value;
• wherein an effective wind speed is estimated using a turbine model, taking into account at least one of actual power produced, actual rotor speed, and actual pitch angle and wherein the performance parameter comprises the effective wind speed.