Dynamic analysis of a 5 MW Barge-type FOWT with two-mooring failure of wind-wave misalignment scenarios

Abstract

A floating offshore wind turbine (FOWT) experiencing two mooring failure can substantially escalate the risk of persistent damage to the remaining moorings. Industry standards mandate that FOWTs must demonstrate the capability of maintaining self-sustainability even in the occurrence of dual mooring failure. Therefore, it is importance to investigate the dynamic response of wind turbines in the case of two mooring line failure. In this study, a novel coupling method of FAST and AQWA was used to analyze the dynamic response of a 5 MW FOWT installed on a barge platform when two mooring lines fail at the same corner. The time-domain response processes of rated and extreme sea conditions were simulated for different failure time intervals (0s, 60s, and 1500s), and the dynamic response of the platform and the change of mooring line tension at each stage are regularly explored. The results indicate that a shorter interval between two mooring line failures results in a more unstable FOWT state. The center of gravity of the wind turbine presents an irregular spiral trajectory, and the platform response exhibits varying characteristics at each stage of the failure process. The transient effect is smaller as the wind turbine approaches the motion limit state.