The influence of uncertain soil conditions on the dynamic response of offshore wind turbines using an efficient time-domain model

The present paper investigates the influence of uncertain soil conditions on the stochastic dynamic responses of monopile-supported offshore wind turbines (OWTs) due to the dynamic soil-structure interaction (SSI). First, a reduced-order aero-hydro-servo-elastic model of the OWT is established based on the multi-body dynamics formulation and analytical-dynamics method. Next, using the dynamic impedance functions of the soil-pile system obtained from semi-analytical frequency-domain solutions, consistent lumped-parameter models (LPMs) are calibrated with very few internal degrees of freedom. A fully-coupled reduce-order OWT-SSI model is then obtained by coupling the LPMs with the aeroelastic model, which enables computationally efficient time-domain simulations as well as the uncertainty quantifications in the probabilistic setting. Different combinations of the stochastic wind and wave loads have been considered. The influence of the parameter uncertainty of soil on the responses of the OWT is evaluated by means of Monte Carlo simulation.