Wind-induced response of an offshore wind turbine under non-neutral conditions: A comparison with Hywind Scotland

Abstract

In this study, aeroelastic simulations of a 5 MW spar wind turbine are performed by using simulated wind fields that are representative of surface layer marine atmospheric turbulence under different atmospheric stratifications. The spar floater's motion responses from the simulations are then compared with the observations from Hywind Scotland's 6 MW spar wind turbine. The platform's pitch and yaw motions from the simulations are consistent with the observations, in terms of mean wind speed and atmospheric stratification. The simulations and the observations show that a stable atmosphere induces the lowest platform pitch and yaw motions compared to neutral and unstable stratifications. Nonetheless, the discrepancy of platform motions between stable and unstable conditions is more pronounced from the observations than in the simulations. Uncertainties associated with the estimation of the atmospheric stability and the modelling of the turbulence's co-coherence for lateral separation may partly account for the discrepancies between the observed and the simulated motion responses of the spar wind turbine.