Modeling and dynamic analysis on spar-type floating offshore wind turbines system via structure-preserving iterative method

As one of the mainstream systems for deep-sea wind power generation, the dynamic behavior of spar-type floating offshore wind turbines directly affects operational stability and power generation efficiency. The complex structure of spar-type floating offshore wind turbines systems and strong coupling between components pose significant challenges to dynamic modeling and analysis. Focusing on the Norwegian Hywind spar-type floating wind turbine system, this paper establishes a coupled dynamic model of the spar-type floating offshore wind turbines system based on Hamilton's variational principle. For the rigid body motion part of the coupled dynamic model, the symplectic Runge-Kutta method is used for solution; for the blade flexible vibration part of the coupled dynamic model, the generalized multi-symplectic method is employed; a coupled iterative algorithm is designed to realize structure-preserving numerical analysis of the coupled dynamic model. Using the established structure-preserving iterative algorithm, the dynamic response of the spar-type floating offshore wind turbines system under rated wind speed conditions is simulated. The influence laws of wind speed and mooring system tensile stiffness on the dynamic response of the spar-type floating offshore wind turbines system are explored respectively, and the dynamic responses of the spar-type floating offshore wind turbines system under different wind field types (steady wind and turbulent wind) are obtained. These results provide important references for the dynamic stability design and structural design of spar-type floating offshore wind turbines systems.