COUPLED SIMULATION BETWEEN FAST AND HYDRO-STRUCTURAL CODE FOR A FLEXIBLE FOWT CONSIDERING BLADE PITCH CONTROL MALFUNCTION

摘要

In this research, a coupled numerical simulation method for a Floating Offshore Wind Turbine (FOWT) is developed. Flexibility of the platform and blade pitch control malfunction can be accounted for by the proposed method. The numerical method is validated qualitatively against a series of scaled model experiment and further simulations are carried out to predict the structural load due to the abrupt failure of blade pitch control system. The influence of blade pitch malfunction for a FOWT is confirmed by utilizing a SPAR and a semi-submersible type floaters and compared against onshore wind turbine case. The behavior and tendency for combined effect of wind and wave is compared and the tool developed is validated. It is found that the abrupt change of the rotor thrust induces the tower flexible modes for the onshore case while almost rigid body motions are the dominant for the floater cases with almost no excitation of the flexible vibration mode. The maximum bending moment after malfunction is almost comparable among the onshore and floating cases however it is observed that the time duration during which the vertical bending moment takes the largest value is different.