DESIGN AND PERFORMANCE OF A PASSIVE VIBRATION CONTROL DEVICE FOR HAWT

This study proposes an innovative technique for reducing wind-induced stress at the base of a horizontal axis wind turbine (HAWT) and its foundation. The technique involves the use of a relaxed base constraint composed of rotational springs and friction devices in parallel, which dissipate energy to reduce bending moment demand while limiting displacement increase within acceptable limits. The aim of this study is the evaluation of a HAWT controlled by a rotational friction damper (RFD) under different wind load conditions for which the turbine is also operational, and studying the effectiveness of the proposed technique in multiple states. In this direction, spectrum compatible wind loads have been generated through the use of the QBlade® software and the European standard IEC61400-1. An optimization procedure has been performed to identify the characteristics of the device providing a satisfactory dynamic response of the turbine against all the evaluated load cases. The results of nonlinear numerical analyses with a 5 MW NREL wind turbine demonstrate that the proposed system significantly reduces the bending moment at the base compared to the conventional 'fixed base' configuration. The proposed system confirms the promising potential of achieving a considerable reduction of the bending moment at the base compared to conventional 'fixed base' configuration.