Energy harvesting and vibration damping on wind turbines

In the last years, Energy Harvesting (EH) for applications in structures and infrastructures is a key research topic, and focuses on different aspects, ranging from the production of small quantities of energy (e.g. for powering structural health monitoring sensors and devices), to the energy production for the sustainability of civil engineering structures. At the same time, the mitigation of vibration in civil engineering structures is an important issue, considering the possible positive consequences on safety and reliability issues (e.g. for the fatigue). This paper deals with an innovative device for the energy harvesting and possibly vibration damping of wind turbines. The device is placed on the connection between the blade and the rotor hub. The efficiency of the device is tested by means of FE numerical analyses, accounting for the detailed loading conditions on the blades. In this sense, a procedure for the accurate modelling of the wind-induced stress on the hub is also provided. The analyses have been carried out in the frequency domain and the effects of the blade rotational motion have been taken into account by superposing a so called “rotating force spectrum” to the wind turbulence action spectrum. The results are provided in terms of Power Spectral Densities (PSDs) of both displacements and wind-induced voltage. The obtained energy by this innovative device can be used in different applications (e.g. alimentation of semi-active control devices or structural monitoring sensors).