Abstract
The co-location of Floating Offshore Wind Turbines (FOWTs) and Wave Energy Converters (WECs) is a promising approach to optimise spatial use and reduce wave-induced loads in the FOWT, potentially reducing fatigue. This dissertation investigates how the co-location of WECs affects the fatigue behaviour of FOWT mooring cables—an essential component for maintaining platform stability under dynamic environmental loads. The main objective is to assess whether co-location can reduce fatigue damage and extend the operational life of mooring lines, and which parameters have more influence.
A comprehensive methodology was employed, beginning with the generation of 30 realistic sea states using ERA5 reanalysis data modelled through a Gaussian copula and Monte Carlo sampling. The wave field was simulated with SWAN to account for the shadowing effects of WECs. WEC-Sim was used to model the dynamic response of the FOWT platform, and MooDy simulated mooring line dynamics. Fatigue analysis was carried out using WAFO, employing rainflow counting and Miner’s Rule. A Taguchi Design of Experiments (DoE) approach was applied to investigate the effects of WEC array configuration on fatigue performance.
Results indicate that the presence and configuration of WECs can significantly alter mooring fatigue response. The optimal configuration achieved a fatigue reduction of 23% in one of the cables. In Cable 1, the cable lifespan was extended by more than three years. The parameters exerting the greatest influence were the number of WECs, the angle of alignment of the WEC array with FOWT, and minimum distance between devices. These findings underscore the importance of array design in enhancing the durability and robustness of co-located offshore renewable-energy systems.