Dynamic response analysis of innovative concrete offshore floating wind turbine platforms

The design and dynamic performance of floating platforms are crucial for advancing offshore wind energy in deep-sea, where stability and dynamic performance are key challenges. Traditional semi-submersible platforms, such as the OO-Star platform, may experience significant motion responses under harsh environmental conditions, affecting operational efficiency and structural integrity. To enhance hydrodynamic performance and stability of the floating platform, this study presents an innovative concrete four-column semi-submersible platform. A finite element model of the platform was developed to define the platform's structure as a prerequisite for the hydrodynamic analysis, and the hydrodynamic coefficients were calculated based on potential flow theory and a compensatory viscous damping method. Subsequently, the ANSYS-AQWA software was used to compute the dynamic responses of the four-column platform in six degrees of freedom. Time-domain and frequency-domain analyses were employed to compare the dynamic responses of the four-column platform and the OO-Star platform under varying wind and wave conditions. The results demonstrate that the four-column platform has superior hydrodynamic performance compared to that of the OO-Star platform. Specifically, under normal operating conditions, the average angular displacement responses of four-column platform are reduced by 52.30 % in the pitch and 60 % in yaw directions. Under extreme shutdown conditions, the dynamic response of the four-column platform is significantly reduced, compared to that of the OO-Star platform. Furthermore, the variation in mooring tension for the four-column platform is more stable, suggesting that it exhibits superior stability combined wind and wave actions.