Contribution to the advanced control strategies of a tidal turbine generator conversion system.

Abstract

This PhD thesis models the whole power chain of a tidal current turbine system and investigates the use of passivity-based control strategy to improve power quality. First, a passivity-based voltage control method is proposed to address the problems faced by the conventional PI controls in the machine-side of the tidal current generation system. Second, a passivity-based current control combined with fuzzy logic strategy is investigated. The proposed control strategy uses a PI loops to design the control law and the desired torque on the generator-side. Finally, a passivity-based backstepping control and fuzzy logic control is proposed. In this context, the backstepping strategy is selected to improve speed tracking error convergence, while the fuzzy logic controller is introduced to design the desired torque and introducing more robustness properties over the nonlinear dynamical and time-varying parameters of the closed-loop system. in the present work, the tidal conversion system is connected to the grid, thus, a classical PI control is adopted for the grid-side converter, for injecting a smoothed power to the grid.