Dynamic Modeling of H-Type Floating VAWT Considering the Rigid-Flexible Coupling Motions

Abstract

Dynamical characteristics of the H-type floating VAWT (vertical axis wind turbine) were studied. The wind turbine blades and the tower were treated as flexible bodies, and the floating foundation was treated as the rigid body. Considering the nonlinear deformations of the flexible bodies, the Lagrangian equation was used to establish the dynamic equations of wind turbine system. The loads included the wave forces, the wind loads, the mooring forces and the damping forces of the wind turbine system. A numerical calculation code was developed and verified. The innovation of the code is the coupling of rigid-flexible-aerodynamic-hydrodynamic of the floating wind turbine system. Taking the 5MW wind turbine as an example, the directions of the wind and the wave were considered as the same. Then the dynamic responses of the floating foundation, the tower and the blades were calculated. The results show that the wave frequency is the main frequency component of the responses of pitch, heave and surge of the floating foundation. 2P frequency (P is the rotational frequency of the wind turbine) accounts for a higher proportion for the sway, roll and yaw of the floating foundation. 2P and 4P are the main frequency components of the tower motions. 1P is the main frequency component of the blades’ motions. The 2nd mode of the blades and tower are considered. In the following research, the higher modes should be considered to improve the calculation accuracy. Besides, the model test is needed to verify the model further in the subsequent work.