Design and dynamic response analysis of a 15 MW semi-submersible floating wind turbine

• Introduction of a novel design for a 15MW lightweight semi-submersible offshore floating wind turbine platform. • Intact stability analysis conducted using static mechanics principles. • Comparative hydrodynamic analysis of the novel platform in relation to traditional designs. • Investigation on platform responses under combined wind, wave, and current loads. • Comprehensive analysis of platform motion and mooring line tension under varying incidence angles. • The impact of wind, wave and current misalignment on mooring line tension and platform response. • Assessment of the platform's response and mooring line tension under the scenario of mooring line failure. As offshore wind turbine technology continues to mature, the development of offshore wind farms is progressively advancing into deeper waters. This study introduces an innovative design for a semi-submersible floating wind turbine platform, specifically tailored for medium water depth applications with a 15 MW wind turbine. The platform features a three-column and two-pontoon configuration, incorporating a variable column diameter to optimize weight and cost efficiency. Structural braces are integrated to enhance the stability of the columns and pontoons, while also addressing potential buckling concerns. The intact stability of the new platform is first evaluated and validated, after which numerical models for both the proposed platform and traditional designs are developed using SESAM software. Key hydrodynamic parameters, including added mass, potential flow damping, first-order wave forces, mean drift forces, and amplitude response operators, are systematically compared and analyzed to assess the platform’s overall performance. Subsequently, a comprehensive series of studies is conducted to analyze the behavior of the new platform. These investigations explore the platform's motion response under various combinations of wind, wave, and current conditions, while also examining the effects of different incidence angles on both platform motion and mooring line tension. Additionally, the impact of the misalignment of wind, wave, and current directions on platform performance is assessed. The platform's resilience under extreme conditions is further evaluated through an analysis of its motion response in the event of a mooring line failure. This extensive study offers valuable insights into the performance, stability, and operational behavior of the proposed semi-submersible floating wind turbine platform under a diverse range of environmental and operational scenarios.