Effects of long-period ground motion and SSI effect on dynamic response of wind turbine

For large-scale wind turbine structures built on soft soil foundation, effects of both long period ground motion and soil-structure interaction (SSI) should be considered. Here, in order to fully study effects of long period ground motion and SSI on dynamic response of wind turbine tower structures, firstly, based on a certain 1.25 MW variable pitch wind turbine structure, an integral finite element (FE) model for the wind turbine structure consisting of blades, nacelle, tower and foundation was established to conduct modal analysis. Secondly, two long-period waves (HKD054 wave and CDAO wave) and an ordinary wave (EI-Cento wave) were selected in the worldwide earthquake record database, and time-frequency characteristics of the two kinds of seismic waves were analyzed contrastively. Moreover, two FE dynamic models for the wind turbine structure considering SSI effect and not considering SSI effect were established, respectively. Finally, the software ANSYS and the time history analysis method were used to analyze seismic responses of the wind turbine structure considering SSI effect and not considering SSI under action of the two kinds of seismic waves. In addition, collision between blade and tower, stress concentration in door hole area, failure of main shaft in nacelle under action of shear force and failure of foundation were further studied. Results showed that under action of long-period seismic waves, the wind turbine structure responses of displacement, acceleration, stress and internal force are larger than those under action of ordinary seismic wave, some responses even are amplified by SSI effect, so long-period ground motion and SSI effect should be considered in the seismic design of wind turbine structures, especially, in soft soil foundation regions; the connecting area between tower and door frame, and the weak areas of main shaft in nacelle and foundation need to be appropriately enhanced. © 2021, Editorial Office of Journal of Vibration and Shock. All right reserved.