A semi-coupled analysis framework for the dynamic optimization of hybrid wind–wave energy platforms

Introduction: The integration of wave energy converters (WECs) with floating offshore wind turbines (FOWTs) presents a promising pathway to increase power density and improve platform stability, though accurately modeling these complex hybrid systems remains computationally prohibitive for rapid design iteration. This paper presents a refined, two-tiered, semi-coupled analysis framework utilizing OrcaFlex and WEC-Sim to overcome this barrier. Materials and methods: Initially, the methodology is verified by calibrating a DeepCWind-Wavestar model against published fully coupled data, demonstrating excellent agreement in the critical heave degree of freedom. These validated parameters are then applied to a 15 MW VolturnUS-S platform integrated with RM3-type WECs to conduct an advanced optimization study for the Illawarra region, Australia. To efficiently evaluate stochastic irregular sea states, the study employs a mathematically justified short-duration, phase-matched simulation technique utilizing cumulative variance convergence to isolate structural damping. Parametric sweeps of WEC mass and power-take-off (PTO) damping reveal a critical power–stability Pareto frontier. Results: The results demonstrate that optimized WEC configurations act as highly effective dual-purpose motion-suppression devices, reducing dynamic surge, heave, and pitch variances by up to 80% under rated collinear conditions. Conclusions: Despite inherent limitations in resolving second-order horizontal drift forces, this work validates the computationally efficient, semi-coupled approach as a robust tool for the preliminary parametric design and dynamic optimization of hybrid marine platforms.