Power capture optimization of variable-speed wind turbines using an output feedback controller

Abstract

One of the major factors that can increase the efficiency of wind turbines is through control of the rotor speed to track the optimal value. A high performance controller can significantly increase the amount of energy that can be captured from wind. The main problem associated with controller design is the presence of uncertainties in the dynamic model of the system, which can be associated with unknown constant parameters and/or unmodeled dynamics such as external disturbances. several adaptive and robust control approaches have been developed to account for these uncertainties. In this paper, a robust controller is presented that compensates for both types of uncertainties; the full mechanical and electrical dynamics of the turbine are considered. These dynamics require acceleration of the rotor to provide feedback information which is not available in sufficiently accurate form during practice. Therefore, in this approach, an observer estimates this information using the speed of the rotor as the output, with the estimation error considered during the stability analysis. This presents one of the main advantages of the approach; the simulation results illustrate the effectiveness of the controller.