Mooring control of semi-submersible structures for wind turbines

The paper deals with the mooring control of tri-floater support structures for wind turbines; both catenary and vertical tensioned lines are considered. Operational and extreme climate conditions are examined, with reference to three different locations in Southern Mediterranean Sea. Mooring system is dimensioned in such a way that the offset due to environmental actions is restrained within allowable limits. The response of the platform is assessed in terms of: static forces due to turbine thrust, wind and current drag forces and steady drift force; the wave frequency montion RAO curves; the low frequency second order wave motins. Finally, assuming the Dutch tri-floater structure as a test case, a parametric study is carried out to identify the most suitable mooring configurations , varying the water depth in the range between 50 and 200 m.