Beyond the linear limitations by combining switching and QFT: Application to wind turbines pitch control systems

Abstract

Abstract This paper introduces a methodology to design a family of robust controllers able to go beyond the classical linear limitations. Combining robust designs and stable switching, the new controllers optimize the time response of the system by fast adaptation of the controller parameters during the transient response according to certain rules based on the amplitude of the error. The methodology is based on both a new graphical stability criterion for switching linear systems and the robust quantitative feedback theory (QFT). It is applied to the design of a pitch control system, which is one of the most critical issues in wind turbines, where a tight combination of high reliability (robustness), minimum mechanical fatigue and performance optimization is required. Copyright © 2008 John Wiley & Sons, Ltd.