Vibration control of spar-type floating offshore wind turbine towers using a tuned mass-damper-inerter

This paper investigates the use of a passive tuned mass-damper-inerter (TMDI) for vibration control of spar-type floating offshore wind turbine towers. The TMDI is a relatively new concept as a passive vibration control device. The configuration consists of an "inerter" attached to the tuned mass, parallel to the spring and damper of a classical tuned mass damper (TMD). The inerter provides a mass amplification effect on the classical TMD. The presence of the inerter virtually increases the mass of the damper leading to greater vibration control capabilities. This enables one to achieve improved vibration control using a lighter damper. Using a lightweight damper is particularly important for an offshore wind turbine because increasing mass on top of the tower can destabilize the overall system and increase tower vibrations, as demonstrated in this paper. The development of a passive TMDI for an offshore wind turbine tower has been proposed in detail in this work. Numerical simulations have been performed and results are presented demonstrating the impressive vibration control capabilities of this new device under various stochastic wind-wave loads. It has been shown that the TMDI has considerable advantages over the classical TMD, achieving impressive response reductions with reductions in the stroke of the tuned mass. The TMDI has been shown to be a promising candidate for replacing the classical TMD for offshore wind applications.