Structural monitoring and smart control of a wind turbine

The remarkable growth in height of wind turbines in the last years — for a higher production of electricity — makes the issues of monitoring and control of such challenging engineering works pressing than ever. The research herein proposed is addressed to monitor the structural demand imposed to the tower as well as to bound it within given limits thanks to the presence and automatic remote control of smart devices at the base of the tower. The latter are magnetorheological (MR) dampers, i.e. special dissipative devices able to change, almost in real time, their mechanical behaviour according to the intensity of current feeding them. A specific control algorithm is proposed to drive MR dampers during severe wind loads. It aims to instantaneously calibrate the current to be supplied to the MR dampers, i.e. their “stiffness”, so as to reduce stresses and displacements imposed to the wind tower. The idea of a variable base restraint for the tower, made up of an hinge and a set of vertical MR dampers, as well as the effectiveness of the above controller, have been experimentally test by means of a shaking table facility at the Denmark Technical University. Two extreme wind loads have been reproduced to assess the control system under very different types of action. The results gathered, encouraging for further investigations, are presented and discussed, also looking at possible further developments.