Dynamic analysis of hybrid mooring system and power cable response for a semi-submersible floating wind turbine at intermediate water depth

This study investigates the dynamic performance of a 66-kV power cable for a 15-MW floating offshore wind turbine (FOWT) in 70 m water depth. Two mooring configurations are compared: a full chain catenary system (M1) and a chain–polyester (PET)–chain semi-taut system (M2) across operational and parked conditions with both north and south wind scenarios. Coupled responses are systematically analyzed, including mooring line tension, platform motions, and power cable performance in terms of maximum tension, maximum curvature, and fatigue life. Additionally, the study assesses hybrid mooring configurations incorporating buoys and clump weights. Results show that the M2 system improves motion stability and reduces cable fatigue, particularly under extreme south wind conditions. While the lazy wave configuration effectively decouples platform motions from cable dynamics, environmental load direction remains a primary driver of surge excursions and fatigue. These findings emphasize the importance of load directionality and mooring design in intermediate water depths. Future work should focus on optimizing cable installation locations to enhance system reliability.