Analysis of FOWT dynamics in 2-DOF hybrid HIL wind tunnel experiments

This paper presents the main results of experimental hybrid/HIL wind tunnel tests of the National Renewable Energy Laboratory (NREL) 5 MW wind turbine coupled with the DeepCwind semi-submersible floating platform. Experiments in still water and in irregular waves without wind are compared to corresponding FAST simulations in order to assess the effectiveness of the proposed HIL methodology and to highlight the main sources of uncertainty. Tests are repeated under three wind conditions, corresponding to different wind turbine operating points, to evaluate the effect of the aerodynamic force field on the overall system response. Experimental results are compared to the output of FAST simulations to investigate its prediction capability with respect to the influence of unsteady aerodynamic loads on the FOWT dynamics.