Magnetorheological Dampers for Vibration Control in Wind Turbines

The actual trend in wind turbines is toward taller and taller towers to let them be excited by stronger winds and thus producing power in cost-effective ways. The structural design is based on peak stresses corresponding to strong wind gusts. However, practical limits in the design and the cost of the structural part of wind turbines cause the need of putting the blades in a “safe mode” when the wind exceeds some threshold values and, in turn, of interrupting the power generation. Although many different passive control systems have been proposed in the literature, only a few research has been devoted to explore the potential of semi-active (SA) systems. Additionally, experimental data on SA structural control systems applied to wind turbines are completely missing. The present paper describes an experimental activity on a 1:20 scale wind turbine mock up equipped with a SA control system based on the exploitation of 2 magnetorheological (MR) dampers. A purposefully-written control algorithm is first introduced and analytically derived. Then the experimental set up, made up of the wind turbine mock-up, the control hardware and the MR dampers, is described. Finally, the experimental tests on a shake table are explained and commented.