Wind turbine structural control using H-infinity methods

Abstract

Wind turbines are complex dynamic structures, exposed to random wind input exciting several structural modes. In recent years, the wind turbines have evolved to large-scale machines, with rotor diameter and tower height attaining unforeseen dimensions compared to initial commercial wind turbines. In this context, the structure design has become more flexible and susceptible to dynamic actions, rising the need for the development of active structural control methodologies. On the other hand, the wind turbine dispose of standard control systems, dedicated to operational control. The use of these control systems to mitigate wind turbine loads is feasible due to the dynamic couplings within the structure, and could provide a significant comparative advantage to the new wind turbine structures. In order to provide structural control from conventional wind turbine control, it is necessary to deploy a suitable modeling and the use of advanced control methods. In this paper, the use of H∞ control design is combined with wind turbine dynamics equations to develop an active structural control to reduce wind turbine tower loading. Dynamic simulations under steady and turbulent conditions demonstrate the effectiveness of the proposed approach.