Thesis (M.Sc.) - Cairo University - Faculty of Engineering - Department of Mechanical Design and Production

This work investigates the efficiency enhancement of fixed-speed wind turbines employed in distributed power generation systems due to their low cost and relatively high reliability. The employment of a continuously variable transmission has been proposed for fixed-speed wind turbines to harvest more energy away from the rated wind speed. In this work, a hydromechanical power split transmission is proposed to replace the conventional fixed-speed transmission. Basically, the continuously variable hydromechanical transmission splits the power into two paths, namely a mechanical path and a hydrostatic path. This configuration enables the wind turbine to efficiently cope with wind speed variations, thus yielding more energy. First, the proposed transmission system configuration has been modeled in a simulation environment to capture the essential dynamics. Second, the main system characteristics have been explored through the study and analysis of the system{u2019}s model. Finally, a control strategy has been designed to drive the system to its optimum operating conditions. The adopted control strategy is based on Extremum Seeking Control theory which proved to have high potential in renewable energy applications. The simulation results, with various wind scenarios, showed the ability of the proposed system, with hydromechanical power split transmission, to significantly increase the energy yield compared to the conventional fixed-speed configuration

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