Dynamic response and mooring optimization of spar-type substructure under combined action of wind, wave, and current

Floating wind turbines (FWTs) have become the preferred structures to exploit offshore winds since a large part of the offshore wind resource is located in deep water zones. In the harsh marine environment, a spar-type substructure is the most promising substructure for FWTs with good structure stability and economic advantages. In this study, the surge, heave, and pitch motions of the spar-type substructure under combined action of wind, wave, and current are analyzed by using the AQWA module of ANSYS. Besides, the effects of different parameters, namely, the mooring line distribution form, fairlead position, and line number of mooring systems, on the spar-type substructure motion response are also investigated. Based on the calculation results, a new spar-type substructure with an optimized mooring system is put forward and analyzed. It can be found that both the dynamic response and the mooring tension of the new spar-type substructure are significantly improved relative to the non-optimized structure. The results of this paper could offer reference for further development of spar-type FWTs in real marine environments.