Nonlinear analysis of a wind turbine tower with a tuned liquid column damper (TLCD)

Tall wind turbines are structures susceptible to high vibration levels, which may affect their optimal functioning and, ultimately, their overall structural stability. One alternative to minimize undesirable vibrations is to install vibration control devices. Various such devices are documented in the literature, with one noteworthy example being the tuned liquid column damper (TLCD), which is a vertical column filled with a liquid mounted at the top of the structure. When the main structure is dynamically excited, the appropriate TLCD vibrates out of phase with the structure, controlling its dynamic response. In this work, the nonlinear vibrations and control of a wind tower-nacelle-blade system subjected to an external harmonic force are studied. Nonlinear Euler–Bernoulli beam theory, together with the Rayleigh–Ritz method and Hamilton’s principle, are used to obtain a set of nonlinear equations of motion, which are, in turn, solved by the Runge–Kutta method. A TLCD device located at the top of the tower is used to control vibrations. First, the effect of blade rotation on the natural frequencies of the system is studied. Second, resonance curves are obtained to study the effect of blade rotation and the frequency of the external force on the nonlinear vibrations of the tower, and the effect of the TLCD on vibration control is also analyzed. This study provides valuable perspectives on the dynamics of offshore wind turbines, contributing to the development of wind energy systems that are more robust and adaptable.