Horizontal-axis wind turbine weathervane yaw differential error

The paper deals with the problem of orientation of the traditional horizontal-axis wind turbine (HAWT) when changing the direction, strength and speed of the wind.
When the wind direction changes, the active swept area of the rotor, which is a circle when the rotation axis and the incoming air flow vector are collinear, decreases and takes the form of an ellipse. This, in turn, leads to a decrease in the electricity volume generation.
Weathervane or rumba-anemometer is a device for registering the speed and direction of wind flow. When the wind direction changes, the device transmits a corresponding signal to the Control System, which in turn generates the command to turn the HAWT rotor on the wind. However, when the wind flow is passing between the rotating blades, the direction of distorted wake is changing, causing eddy formation. As a result the device gives out the initially incorrect data about the direction and velocity of the air flow. Furthermore, when adjusting the position of the rotor (yawing), the collinearity of the rotation axis and the vector of the incoming flow is not achieved, the swept area remains mostly elliptical, and the power generated is proportionally reduced. In accordance with the relevancy of the said problem, the goal of the study was to calculate numerical values of the wake deflection angle in various modes, using the three-dimensional modeling in Ansys CFX software package. The obtained information can be used then to develop the algorithm for eliminating this error.