Parametric Study of a Counter Weight Suspension System for the TetraSpar Floating Wind Turbine

New floating wind turbine designs are needed to reduce production costs and to increase mass production feasibility. The TetraSpar floating wind turbine achieves these goals by being constructed using components highly suitable for standardization and industrialization. The design makes use of a suspended submerged counter weight to obtain a low center of gravity of the floating system, while also allowing a low draft during transport and installation. This novel concept requires a multibody modeling approach to perform a dynamic load and response analysis, as the stiffness between the floating platform and the counter weight is provided by chains. Additional design criteria are required for the counter weight system dependent on a combination of chain capacity and maintaining positive tension in all of the lines. To satisfy these design criteria a global hydrodynamic load and response analysis of the floater and counter weight is performed. In this concept, the counter weight depth contributes significantly to the dynamic properties of the system and therefore a parametric study is conducted. The global response parameters of the rigid-body motion natural frequencies, nacelle accelerations, counter weight chain tensions, and maximum platform-pitch angles are compared. Design recommendations are made for the configuration of counter weight depth and suspension system layout.