Individual Pitch Control for Large Scale Wind Turbines

Abstract

In this thesis a number of advanced control algorithms are developed and applied for use with large scale onshore and offshore wind turbines. Individual pitch control for wind turbines is a relatively recent development, and controllers need to be carefully designed. Algorithms are developed for both optimizing power productions and load mitigation, using various techniques and approaches. Individual pitch control methods for controlling the generator speed and blade flap motions are analysed in publications 1-3. The control methods evaluated are LQG control, diagonal control, gain scheduling and H∞ loop shaping. Individual pitch control methods for controlling the tower motions together with the generator speed and blade flap motions for offshore wind turbines has been evaluated and compared in publication 4. The most important novelty of the work is the development and evaluation of the robust H∞ loop shaping method, which to the author’s knowledge has not been used for wind turbine control before. This method works very well in reducing both fatigue damage of the blades as well as in the support structure, resulting in a robust and efficient controller.