Tuned Mass Damper Inverted Pendulum to Reduce Offshore Wind Turbine Vibrations

Abstract

Wind energy is in a fast development worldwide and is currently receiving great investments mostly for being a clean energy source. Advances in this area are resulting in increasingly high and slender wind turbines, intensifying vibrations in structures caused by its own operation and, also, by wind force. Searching a better performance leads to offshore devices, i.e. wind turbines installed at the ocean next to coast. These structures take advantage of wind forces generated by more intense and consistent wind with less turbulence in these regions. One of the conceptions for this kind of wind turbine is the floating device. A solution to the problem of excessive vibration, which has been studied by several researchers in recent years, is structural control. One of the structural control devices, already extensively studied and implemented in practice, is the Tuned Mass Damper (TMD). An alternative geometry for TMD is the pendulum absorber. However, previous studies have shown that pendulum TMD installed on floating wind turbines requires an excessive length, therefore a different approach is required. In this work it is proposed an inverted pendulum TMD to improve control performance in an offshore wind turbine modeled as an inverted pendulum. This device may be considered as a linear oscillator only for small vibration amplitudes. Numerical simulations are performed to define TMD parameters that improve the control device performance. Good performance is achieved. However, passive devices only work properly for the design frequency range, and wind forces are random type of excitations. Better results would be achieved if a robust control is developed. This study will serve as a basis for the proposition of a semi-active device.