• Analytical model for stability analysis of floating platforms • Metacentric height, righting arm and righting moment of floating wind turbine platforms • Hydrostatic equilibrium analysis of floating wind turbine platforms • Effect of draft, members spacing and KG on stability of floating platforms Floating platform is the core subsystem of the floating offshore wind turbine system, and is the key source of stability besides mooring lines. Hydrostatic stability analysis is the primary step in preliminary design of a floating platform. The stability analysis of platforms is commonly performed using software packages which utilizes panel-based numerical methods. In this study, we have developed an analytical model for nonlinear stability analysis of floating wind turbine platforms. The analytical formulation takes into consideration the nonlinear co-relation between platform degrees of freedoms and its hydrostatic properties. For each prescribed rotation the equilibrium state of platform is determined and the stability parameters are analytically computed. The model also computes the nonlinear hydrostatic restoring forces and thus can also be easily integrated with other floating wind turbine simulation tools. The numerical accuracy of the analytical model is validated against DNV HydroD. Furthermore, a parametric stability analysis is also performed to evaluate the effect of platform draft, member center-to-center span and KG. The draft of the platform primarily influences large angle stability while having negligible effect on initial stability. The members center-to-center span and KG both have significant influence on stability. However, KG inversely influence stability margin as opposed to center-to-center span which has direct relationship with stability. The proposed formulation eliminates the discretization of the platform surface into panels thus significantly simplify the computation. It is computationally efficient, and can be of useful to researcher in the preliminary design of the floating platform.
Ullah et al. (Wed,) studied this question.