MODELLING OF WIND-WAVE MISALIGNMENT FOR FLOATING OFFSHORE WIND TURBINES

The influence of the combined effects of wind and waves onto the performance of a Floating Off-Shore Wind Turbine (FOWT) is analyzed. A study of the wind conditions relative to the position of the aerodynamic rotor has been made, analyzing how the angle of incidence of the wind (angle of attack) varies with the wind direction and the inclination of the wind turbine mast as a consequence of the undulatory movement of the waves. This analysis should result in a theoretical model based on the variation of the angle of attack which allows the characterization of the turbine under the combined effect of the oscillation of the sea surface and changes in relative wind direction to the aerodynamic rotor. The results obtained from this research will allow designers and operators to properly manage the situation under which the FOWT is working for a cross action of wave movement and wind direction. A proposed method to compensate for the aforementioned changes in the aerodynamics of the turbine rotor is a so-called “pitch and yaw compensation” system that allows eliminating the effect produced by the variation in the angle of attack and, therefore, minimizing the effect of oscillation on the generated power generated.