Calculating a wind speed associated with a return period at a proposed wind turbine site. The method comprises selecting a first set of storms from wind speed measurements measured at the proposed site, and selecting a second set of storms from modelled wind speeds, the modelled wind speeds being estimates of wind speeds at the proposed wind turbine site during the measurement period from a mesoscale data set. A comparison is made of characteristic wind speeds of the first and second sets of storms to determine a correction factor. A third set of storms is selected from an extended set of modelled wind speeds from an extended mesoscale data set, and the correction factor is applied to characteristic wind speeds of the third set of storms to provide corrected wind speeds. A wind speed associated with the return period is calculated from the corrected characteristic wind speeds.

Embodiments herein describe a system used to estimate the presence of water on a sensor. A parameter maintains a wind sensor temperature. The parameter can be tracked and evaluated to indicate a likelihood of water on the sensor. Alternatively, or in combination with the above, the sensor is adjusted intentionally or deactivated and reactivated to track a parameter response which is then used to indicate a likelihood of water on the sensor.

A method for calibrating a wind direction measurement for a wind turbine is provided. The method including: measuring plural samples of a relative wind direction representing a difference angle between a real wind direction and an orientation of a measurement equipment, in particular a direction orthogonal to a rotor blade plane, to obtain plural measured relative wind directions; 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; measuring further plural samples of the relative wind direction; and correcting the further measured relative wind directions based on the correlation value, to obtain corrected further measured relative wind directions.

A system and method are provided for controlling a wind turbine of a wind farm. Accordingly, a controller determines a performance differential for the wind turbine at multiple sampling intervals of a yaw event. The controller determines a trendline for the wind turbine correlating the performance differential to a deviation of a wind direction at each of the multiple sampling intervals from an first yaw angle. A difference between an angle associated with the vertex of the trendline and the first yaw angle are utilized by the controller to determine a yaw angle offset. The yaw angle offset is used to adjust a second yaw angle of the wind turbine.

Controlling a wind turbine comprising a wind direction sensor, a yawing system, and a control system for turning the wind turbine rotor relative to the wind. Over one or more time intervals a data set comprising a direction of the wind relative to the wind turbine as measured by the wind direction sensor and a wind power parameter determined as one of a power, a torque, or a blade load of the wind turbine are obtained. The data sets are sorted into a number of bins of different intervals of wind power parameter. or each power bin, a statistical representation of the wind power parameter as a function of the relative wind direction is determined and then used in estimating a wind direction offset corresponding to the relative wind direction where the wind power parameter attains a peak value. The relative wind direction is then adjusted as a function of the set of wind direction offsets to yield more accurate wind direction data which can be used in controlling the turbine.

The invention relates to a method of controlling a wind turbine comprising a wind direction sensor, a yawing system, and a control system for yawing the wind turbine rotor relative to the wind. The method comprises obtaining an estimate for a wind power parameter as a function of a relative wind direction, where the wind power parameter is determined as one of a power, a torque, a blade load, or a blade pitch angle of the wind turbine. At time intervals, a data set is established comprising a wind power parameter and a wind direction parameter as measured by the wind direction sensor. Over time a group of data sets is then obtained for a number of pre-defined wind direction intervals, and a wind direction offset is determined for each interval by comparing the average wind power parameter for that interval with the estimate of the wind power parameter. The wind direction offsets of the different wind direction intervals are used to adjust the wind direction parameter, and applied in the controlling of the wind turbine. The invention further relates to a control system for a wind turbine for performing a control method as mentioned above.

A wind turbine includes at least one wind speed sensor, a number of pitch-adjustable rotor blades, and a control system for changing the pitch of the rotor blades and/or a generator torque. The the control system determines at time intervals an error parameter as the difference between an estimated wind speed and a measured wind speed as measured by the wind speed sensor. Then, based on a number of pre-defined wind speed intervals, a group of error parameters is obtained over time for each wind speed interval. For each wind speed interval and for each group of error parameters a wind speed offset is determined based on the average of the error parameters within the group which wind speed offsets are used in adjusting the measured wind speed.

Controlling a wind turbine comprising a wind sensor, a number of pitch-adjustable rotor blades, a yawing system, and a control system for yawing the wind turbine rotor relative to the wind and for changing the pitch of the rotor blades. A wind parameter is measured by the wind sensor, and is indicative of the wind speed and/or the wind direction relative to the wind turbine. At least a first and a second set of wind correction parameters for different production modes of the wind turbine are obtained. The production mode of the wind turbine is then determined, which may be one of at least normal operation or non-production, and the measured wind parameter is then adjusted as a function of the set of wind correction parameters corresponding to the production mode at the time of adjusting. Hereby a more precise wind parameter is obtained which can be used in the controlling of the turbine.

A control system for yawing a wind turbine rotor relative to the wind and for changing the pitch of rotor blades. A wind direction parameter is measured by a wind direction sensor. The wind direction is calibrated as a function of a predetermined offset parameter, and then adjusted as a function of a wind direction compensation parameter. The adjusted relative wind direction is then used in the determining of a control parameter of the wind turbine. The parameters for the calibration and adjustment of the relative wind direction are obtained from a set of data comprising the wind direction relative to the wind turbine over time and as measured by the wind direction sensor on the wind turbine and as measured by a second wind direction sensor.

A method of determining an orientation of a nacelle of a wind turbine, wherein the nacelle carries a Global Navigation Satellite System (GNSS) sensor, the method comprising: yawing the nacelle between a series of orientations; obtaining locus data based on a series of calibration positions measured by the GNSS sensor, wherein each calibration position is measured by the GNSS sensor when the nacelle is in a respective orientation of the series of orientations; storing the locus data; after storing the locus data, measuring a new position with the GNSS sensor; and determining the orientation of the nacelle on the basis of the stored locus data and the new position.