Different from the fixed-based wind turbines, the floating type wind turbines are regarded as under a free–free end operating condition. The tower structure of a floating offshore wind turbine is an integrated part connecting the nacelle and support platform. An analytic solution is presented in this technical brief for the free-vibration of the tower structure of a spar-type offshore wind turbine. The tower structure is modeled as a free–free beam based on Euler–Bernoulli beam-column theory. The platform and the nacelle are considered as two large mass components connected by torsion springs at two tower ends with different stiffness. The effects of system parameters on the natural frequencies are investigated under a range of variables, including the tower structure parameters, platform and nacelle parameters, and the connection types. Nonlinear relationships between those variables and the natural frequency of the tower structure are numerically found and some design issues are discussed for the spar-type floating wind turbines.
Issue Section:
Technical Brief
Keywords:
Design of offshore structures,
Dynamics of structures,
Floating,
Offshore structures,
Structural mechanics ,
Moored production systems,
Foundation,
Ships in ice
Topics:
Offshore wind turbines,
Spar platforms,
Wing spars,
Wind turbines,
Design,
Dynamics (Mechanics),
Floating wind turbines,
Free vibrations,
Ice,
Manufacturing systems,
Mooring,
Offshore structural design,
Offshore structures,
Ships,
Springs,
Stiffness,
Structural analysis,
Structural mechanics,
Torsion
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