Dynamic modeling and characterization of a wind turbine system leading to controls development

With the growing energy demand and need to decrease greenhouse gas emissions there has been a rise in the popularity of renewable energy systems. One of the most popular renewable energy systems over the past decade has been the wind turbine. Technological advances in modeling, prediction, sensing and control combined with the current shift towards decentralized power have prompted development of wind energy systems. Decentralized distribution allows for lower transmission losses because of the closer proximity to the consumer and greater regional control. The wind turbine has positioned itself as the leading energy system to serve as a cornerstone in the development of decentralized energy distribution. This research focuses on the development of a nonlinear dynamic model of a variable speed wind turbine. The modeling effort is followed by model validation against published data. Subsequently, benchmark control problems and existing control strategies are reviewed from literature. Emphasis is placed on variable speed form of operation. Control strategies are studied for two different operating modes of a wind turbine, namely operations below and above the rated-speed. For the former case control design is based on power maximization and for the latter the control design is based on power regulation. For each case, standard control strategies appearing in literature for individual operating regimes are implemented, and thereafter focus is placed on robust performance. Subsequently attempts are made to design new and/or improved strategies. The new control strategies proposed in this research are based on principles from nonlinear control. Furthermore, the research attempts to apply certain relatively new techniques such as extremum-seeking-control to the wind-turbine application. Finally, the research proposes a switching method to combine the control strategies for individual operating regimes