On the Correlation Between Floating Wind Turbine Accelerations, Rotor and Tower Loads

Abstract

Abstract Research in floating wind turbine resulted in the publication of a number of studies comparing wind turbine loads on a variety of floaters and fixed foundations. Some of them concluded that the blade and drivetrain loads would only be marginally increased -if increased at all — when a turbine would be installed on a floater [1] [2] and [3]. This paper proposes to evaluate how rotor and tower loads are correlated to nacelle acceleration, wind and wave conditions. It can somehow be considered as an extension to a barge-type floater and onsite measurements, of published work applied to fixed offshore wind turbines [4] and a spar-type floating wind turbine [5]. The body of data used for this exercise includes results from full-scale prototype measurements and simulations for a variety of turbine ratings. It can be concluded that in power production cases, blade and main shaft loads are only weakly correlated to nacelle low frequency accelerations and hence wave conditions, hence aerodynamic loads are still the main driver for rotor and tower top loads. In rotor-idling conditions, the situation is mainly dependent on the wind speed range, but aerodynamics are the largest contributor of blade and main shaft loads in severe wind conditions. These results can help understand where design uncertainties lie in floating wind turbine loads.