Abstract: The paper presents the theories of an in-house time-domain simulation code for floating offshore wind turbines. The unsteady blade-element-momentum method with correction methods is applied to calculate aerodynamic loads. Combination of the potential-flow theory and the Morison’s formula are used to calculate hydrodynamic loads. The quasi-static catenary mooring method is implemented to calculate restoring forces from mooring lines. Kane’s dynamic equations are used to establish dynamic governing equation for the system. The generator-torque controller and the full-span rotor-collective blade-pitch controller are used to regulate wind energy tracking. Subsequently, feasibility testing of the code is conducted by a series of code-to-code comparisons, which will benefit researchers in their theoretical study and development of numerical code for floating offshore wind turbines.

Key words: floating offshore wind turbine; numerical code; potential-flow theory; Kane’s dynamic equations; blade-element-momentum