Dynamic response reduction of floating offshore renewable energy applications with a high-damping mooring system

This study introduces an innovative high-damping mooring system for offshore renewable energy applications to enhance the stability and reduce structural responses of floating platforms subjected to wind/wave forces. The mooring cables in this system are linked to the platform via a rigid rotatable arm, with the arm’s movement restricted by a spring and a damper in parallel positioned between the arm and the platform. Simplified and dynamic models of the proposed mooring system are presented, respectively, for damping evaluation and coupled numerical analysis. The 5 MW NREL offshore on the OC3-Hywind spar is selected for performance evaluation and optimization. Damping of the platform with the proposed mooring is obtained and maximized based on complex modal analysis. The results show that a maximum of 11.4% additional damping ratio can be achieved for the surge and sway motions of the platform with an implementable high-damping mooring system. Coupled analysis of the platform under irregular waves and joint wind-wave loads shows that the standard deviation of platform displacements can be reduced by up to 40% and the dynamic tensions of the cables can be reduced by approximately up to 62%.