Variable Speed Drives for Household Wind Energy Systems: Model Predictive Control of the Squirrel Cage Induction Generator with the Nine-Switch Converter

Household power generation is a key part of smart grids. Among the power sources, variable speed wind turbines offer good power output with reliability. This chapter investigates the use of a squirrel cage induction generator in a variable speed drive system for the aforementioned application. In this downsized scale of power, reduced-count switch converters are interesting alternatives, for the sake of cost and size reduction. Therefore, this work applies the Nine-Switch Converter (NSC) in the integration of a squirrel cage induction generator onto the grid, with use of Finite Control Set Model Predictive Control (FCS-MPC), a powerful control theory, specially for power electronics. The converter is analyzed, with focus on its available voltage vectors, leading to the development of two structures of FCS-MPC: the concentrated approach and the decoupled approach. Furthermore, the decoupled approach enables the incorporation of duty cycle optimization into FCS-MPC for the NSC, which leads to improvements on the generator torque ripple and on the grid active power ripple. Additionally, considerations are made about the use of NSC wind energy system also for grid reactive power compensation. All the considerations are accompanied by simulated results of the considered system. As a result, the NSC is a feasible alternative for variable speed drive wind energy systems in household applications.