Modeling and dynamic simulation of a hybrid floating wind–wave platform with integrated flap-type wave energy converters

• A hexagonal wind–wave platform with integrated flap-type wave energy converters. • Coupled wind–wave–control model implemented in WEC-Sim for time-domain simulation. • Sensitivity study identifies flap size and tower length as dominant design drivers. • Flap-angle sweep from − 55 ∘ to + 55 ∘ shifts steady-state platform pitch from + 5 . 54 ∘ to − 5 . 24 ∘ . • AEP: 16.86 GWh (wind) + 3.65 GWh (wave), with wave energy contributing ∼ 17.8 % of total hybrid output. Offshore renewable energy systems offer promising solutions for sustainable power generation, yet most platforms harvest either wind or wave energy in isolation, and even in hybrid wind–wave systems, wave energy converters (WECs) are often treated as secondary components. This study presents a hybrid floating platform integrating a wind turbine with three oscillating surge WECs into a hexagonal semi-submersible structure. In this configuration, the flaps are integrated with the platform geometry to provide both energy extraction and buoyancy-related stability. A modeling and simulation framework was implemented using WEC-Sim and benchmarked against the NREL 5 MW semisubmersible. Metacentric height analysis confirmed hydrostatic stability across a range of flap angles. Sensitivity analysis of twelve geometric variables identified flap dimensions and tower length as dominant drivers of stability, energy capture, and stress. Time-domain simulations showed dependence on wave incidence angle, with variations in flap power sharing, capture width ratio (CWR), and platform response. The feasibility of using flap sweeps to modulate pitch motion was demonstrated. Annual energy production estimates indicated 16.86 GWh from wind and 3.65 GWh from wave energy, with WECs contributing about 17.8 % of the total. These results highlight the potential of integrated wind–wave platforms and motivate future work on structural modeling and advanced control.