Application of spherical tuned liquid damper in vibration control of wind turbine due to earthquake excitations

Summary A spherical tuned liquid damper (TLD) is proposed as a cost-effective method to reduce the earthquake-induced vibration of wind turbines. A 1/20-scale test model was designed to investigate its performance of controlling the structural vibration. A series of free and forced vibration experiments with different water depths in hemispherical containers were performed on the shaking table. Three measured ground acceleration-time histories, including El Centro NS, El Centro EW and Tianjin EW, were selected to verify the effectiveness of spherical TLD in suppressing the earthquake-induced vibration. The experimental results showed that the spherical TLD could effectively improve the damping capacity of the test model. The standard deviation of the dynamic response could be effectively reduced when the excitation frequency was approximately equal to its fundamental frequency. The liquid sloshing motion in containers was characterized by a highly nonlinear and complex nature. The effectiveness of spherical TLDs does not increase linearly as the mass of water in containers and is influenced greatly by the frequency components of earthquake excitations. For El Centro EW excitation, the standard deviations of the dynamic responses could be reduced more than 40% when the liquid mass was about 2% of the generalized mass. Copyright © 2015 John Wiley & Sons, Ltd.