For the study of the double wave configuration for the dynamic power cable of a Floating Offshore Wind Turbine (FOWT) in shallow water, this paper presented a comparison of the hydrostatic and hydrodynamic performance between a lazy wave and a double wave configuration. The double wave shape’s parametric presentation was first developed based on an extension of a previous parametric lazy wave shape. An aero-hydro-servo-elastic integrated model fully coupling the FOWT and the dynamic power cable was then proposed in the SIMO/RIFLEX code for numerical simulation. Subsequently, the strain-cycle curve and the rain flow counting method were employed to estimate the copper conductor’s fatigue damage. The bending moment was proved to provide the major fatigue contribution. The results showed that the double wave offered superior performance than the lazy wave. The second arc of the double wave configuration was proved critical for suffering high curvature, tension, and fatigue damage. A lower position and less hogged wave arc were suggested for the determination of the double wave shape.

Offshore wind turbines serve as critical infrastructure components in marine renewable energy systems, enabling sustainable energy extraction within offshore engineering frameworks. Monopile foundations for offshore wind turbines in deep-water environments are subjected to strong nonlinear wave actions. This study introduces a novel composite monopile foundation specifically designed for deep-sea applications, with its fully nonlinear hydrodynamic performance systematically investigated using potential flow theory. The novel hybrid monopile incorporates a concrete-filled double-skin steel tubular (CFDST) configuration to reduce pile diameter at water level. In the numerical model, the higher-order boundary element method (HOBEM) is implemented to resolve boundary value problems at each temporal iteration. Following numerical validation, nonlinear wave loading and run-up characteristics for the CFDST hybrid structure are quantified, while the limitations of Morison’s equation for large-scale structures under strongly nonlinear wave conditions are concurrently assessed. Results indicate that CFDST implementation effectively attenuates both nonlinear hydrodynamic forces and wave run-up amplitudes, enabling safer and more economical design approaches for deep-water offshore wind turbine foundations.

This paper carried out coupled non-linear aero-hydro-servo-elastic simulations of a semisubmersible floating wind turbine under rated, intermediate and extreme conditions. The NREL 5MW turbine including tower structure is modeled by SIMO-RIFLEX module in SESAM with hydrodynamic and hydrostatic parameters of semi-sub configuration input from WADAM code. A tensioning mooring system