Dynamic Analysis for Dynamic Cables of Floating Offshore Wind Using an Integrated Floater-Mooring-Cable Coupled Model

The fatigue life and structural integrity of dynamic cables are critical to the overall system reliability of floating offshore wind turbines (FOWTs). The prevailing industry practice employs a decoupled analysis method based on Response Amplitude Operators (RAOs), which, however, fails to capture the nonlinear dynamic interactions between the floater and the cable. This limitation can lead to an underestimation of fatigue damage and extreme structural responses under severe environmental conditions, thereby introducing potential risks in engineering applications. To address this challenge, this paper proposes an efficient coupled time-domain analysis method for engineering design. First, an integrated model coupling a Morison-type Tension Leg Platform (TLP) floater, a 16 MW wind turbine under aerodynamic loading, and a nonlinear dynamic cable is developed within the OrcaFlex platform. This model enables the direct simulation of transient dynamic responses of the coupled floater-cable system under combined wind, wave, and current loads. The proposed method is then applied and validated through the Lufeng Oilfield Group Clean Energy Power Supply Modification Demonstration Project. Numerical results demonstrate that under 50-year extreme sea states and internal solitary wave conditions, all key performance parameters of the dynamic cable—including effective tension, minimum bend radius (MBR), and clearance from adjacent tethers—comply with design requirements, with a strength utilization factor below 1.0. The estimated end-of-life (EOL) fatigue life reaches 3.86 × 104 years (incorporating a safety factor of 10), significantly exceeding the required service life. By integrating the traditional two-step process of “RAO extraction plus time-domain analysis” into a single-run coupled simulation, the proposed method enhances analysis efficiency and engineering practicality. This study establishes a coupled time-domain analysis framework for the design of dynamic cables in floating wind applications. Its engineering feasibility is confirmed through a successful application in a demonstration FOWT project in the medium-water-depth environment of the South China Sea, highlighting its value in supporting the safety and economic viability of future deep-water floating wind systems.