Study the Effect of Floating Platform Rotational Disturbance on the Aerodynamic Performance of Offshore Wind Turbine in the Presence of Pitch Control System

In this paper, the effects of a floating platform rotational motion on performance of an offshore wind turbine are investigated. For this sake, the unsteady blade element momentum method is used as the aerodynamic modelling tool. The proposed model has been validated based on data available for the reference turbine in the ground or fixed platform. To estimate the pitch angle as the control parameter in the power adjusting system, the PI controller is being utilized. The rotation of floating platform including three main angular motion as pitch, roll and yaw have been studied which are approximated by a sinusoidal function. Results showed that among rotational motions, the effect of pitch motion is more considerable than roll and yaw motions. In case of pitching motion input, reduction of mean power coefficient for tip speed ratios less that 7 is expected. For high tip speed ratios more than a critical TSR, the trend is reverse with respect to fixed-platform case. Magnitude of change in the power coefficient however depends on several parameters which is explained more in the paper. The same but degraded trend also occurs in the case of roll and yaw disturbances. Moreover, the mean value of blade pitch angle which is an index of control effort is being increased.