Mooring System Optimization for a Spar-Buoy Wind Turbine in Rough Wind and Sea Conditions

A fully integrated optimization framework for designing a complex geometry offshore wind turbine spar-type floating support structure

“…This, however, leaves open the possibility of subsequent fine tuning of the conceptual design solution obtained through optimization based on hydrodynamic and system-level analyses. By addressing the mooring system in the subsequent detailed design optimization or even in a successive but separate optimization algorithm, the dynamic response of the FOWT system, as well as the mooring line tension itself, can be significantly improved by considering an advanced and more complex optimization problem, in which -apart from various line diameters and lengths -different mooring line arrangements and distribution forms can be utilized, the optimum number of lines within the mooring system and best fairlead position can be elaborated, different mooring types can be used or even mixed within segmented lines, and also clump weights can be incorporated (Tafazzoli et al, 2020;Barbanti et al, 2019;Men et al, 2019;Chen et al, 2017).…”

Influence of Clumps-Weighted Moorings on a Spar Buoy Offshore Wind Turbine

“…The potential-flow theory, which is the one adopted in the present study (as opposed to [22], where the strip-theory was employed), is the most comprehensive approach used in HydorDyn and involves frequency-to-time-domain transformations. It requires the definition of the hydrostatic restoring coefficients, the added mass and damping contributions from linear wave radiation, and the incident-wave excitation (Froude-Krilov forces).…”

“…Surge and pitch RAOs are then evaluated for various combinations of mass and position of the weight along the cable. Heave motion was not considered because clump weights have negligible effect on this DOF [22]. As shown in Figure 3, the natural frequencies do not change using different weights at different positions; in contrast, peaks at the natural frequency vary from case to case.…”

“…This type of platform is connected to the bottom of the sea through three catenary cables. Barbanti et al [22] showed, using a genetic algorithm optimization, that the platform response is almost insensitive to the mooring line geometry, while the use of clump weights can reduce the fatigue load and improve the overall system response. Yuan et al [23] studied a hybrid mooring system with clump weights on the bottom part of the cable and buoy near the platform.…”

“…Hordvik [24] analyzed optimized mooring line configurations for the OC3 Hywind spar platform, focusing on the minimization of the mooring line tension. Most of the studies regarding the spar buoy-type platform [22][23][24] have been performed using the strip-theory approach, which is based on Morison's equation [25].…”