Dynamic behaviors of wind turbines under wind and earthquake excitations

Abstract

The dynamic behaviors of wind turbines subjected to combined wind-earthquake loading were investigated. Numerical simulations were performed to examine the influence of wind speed and earthquake intensity on the dynamic behaviors of wind turbines after evaluating the influence of randomness of wind. Subsequently, the effect of start time and input angle of earthquakes on seismic responses of wind turbines was evaluated to explore the temporal and spatial combinations of wind and earthquake loads. It is noted that the wind increases and decreases the response amplitude of the wind turbine under weak and strong earthquake excitations, respectively. Consequently, the most unfavorable seismic load conditions are represented by the wind-earthquake combination in the former scenario and by only the earthquake case in the latter scenario. Because the start time of earthquakes can significantly affect the dynamic response of the wind turbine, sufficient wind samples must be generated to obtain the mean of the response amplitudes. Moreover, the input angle of earthquakes influences the seismic response of wind turbines, owing to the asymmetry of aerodynamic damping and blade stiffness. Consequently, the combination of wind and earthquake excitations in the space domain must be considered prudently.