A semi-analytical model of aerodynamic damping for horizontal axis wind turbines and its applications.

A semi-analytical model of the aerodynamic damping for horizontal axis wind turbines was established. Considering the translational and rotational degrees of freedom of tower-top, aerodynamic damping forces on the rotor were calculated by the blade element momentum theory and simplified to a resultant force at the tower-top and a resultant couple. Thereafter, the semi-analytical solution of modal aerodynamic damping ratios was suggested. Subsequently, the modal aerodynamic damping ratios of the NREL 5 MW and WP 1.5 MW wind turbines were calculated by the semi-analytical solution and identified from their dynamic response to validate this solution. And, the sensitivity analysis was performed to evaluate the influence of control parameters on the modal aerodynamic damping ratios of wind turbines. Finally, the uncouple analysis method with this aerodynamic damping model was used to predict the dynamic response amplitude of wind turbines, wherein the aero-servo-elastic fully coupled analysis were set as the reference method to examine the reliability of this uncoupled method. The results indicated that the uncoupled analysis method employing this aerodynamic damping model can accurately predict the dynamic response of horizontal axis wind turbines excited by a combined wind-earthquake loading, which is significantly better than the existing uncoupled model. ∙ Tower-top translation and rotation are considered in aerodynamic damping model. ∙ Semi-analytical solution of modal aerodynamic damping ratios is established. ∙ Modal aerodynamic damping ratios for NREL 5 MW wind turbine is investigated. ∙ The accuracy of present model is much higher than that proposed by Santangelo et al. [ABSTRACT FROM AUTHOR]