Flexible dynamic modeling and analysis of drive train for Offshore Floating Wind Turbine

Drive train has a significant influence on the reliability of wind turbines. As for the Offshore Floating Wind Turbine (OFWT), the importance of the drive train is even more prominent due to the more complex operating conditions at the ocean. In this study, dynamic characteristics of the OFWT drive train are investigated based on flexible dynamic model. First, this paper presents a flexible dynamic model of the drive train, which includes not only the full coupling of gear meshing but also the flexibilities of planet carrier and ring gear. Then, a corresponding finite element model is established to verify the reliability of the proposed model by comparing natural frequencies and vibration responses. Afterwards, dynamic characteristics of the drive train are analyzed under different excitations, including the time-varying mesh stiffness, wind turbulence, tower shadow, wind shear and platform motions. Results show that resonant peaks of the system are more likely to appear when the mesh frequency or its multiplication of the gear pair 1–2 is equal to the natural frequency. In addition, it is revealed that the tower shadow is the most significant excitation source for OFWT drive train, followed by platform pitch and surge motions.