Posters

Abstract

As wind turbines become larger, their structural components become more flexible and more susceptible to fatigue loading. Especially periodic blade loads are of concern. To reduce such loading, individual pitch control (IPC) is often used and traditionally aims for maximum attenuation of the targeted harmonic blade loads, leading to significant pitch activity. While pitch-input constrained implementations have been proposed in the past, this work proposes an output-constrained IPC control method that only uses pitch actuation when the periodic blade moments exceed predefined bounds. In this way, a trade-off between load reduction and pitch actuation is made. The proposed control method uses the multiblade coordinate (MBC) transformation to transform the blade moments into a nonrotating reference system. By controlling an additional rotation in the MBC transformation, the nonrotating loads can be represented as polar coordinates, enabling a single single-input single-output controller to regulate the magnitude of the nonrotating load. To get insight into the working mechanisms of the controller, results are analyzed from OpenFAST simulations in laminar and offshore turbulent wind conditions. The reduction in damage equivalent load is initially large when partly enabling IPC but leads to smaller returns when operating close to full IPC.