Conexão de Gerador de Indução com Rotor Bobinado à Micro-Rede CC com Conversor Multinível Modular com Submódulos em Ponte Completa

Abstract

In this undergraduate thesis a wind power generation system based on a doubly-fed induction generator connected to a DC microgrid using a modular multilevel converter was proposed. The proposed system was composed by: a stator-side converter, a rotor-side converter, a doubly-fed induction generator and a wind turbine. The topology of modular multilevel converter with full-bridge submodules was adopted as the stator-side converter, connecting the generator’s stator to the DC microgrid. Since a low voltage DC microgrid was considered, the connected wind power generators can have a line voltage higher than the microgrid, which makes necessary the voltage step-down rectifier operation of the modular multilevel converter. For the variable speed operation of the generator, a three-phase voltage source converter with three arms was used as the rotor-side converter, connected to the DC microgrid, performing the vector control of the generator. In order to increase the accuracy of the generation system, a wind turbine described by the two mass model was considered. A control system was proposed to balance the voltage of the capacitors of the modular multilevel converter, to ensure three-phase symmetrical voltages with a waveform close to a sinusoidal wave in the generator’s stator terminals, and to obtain the value of the torque applied on the generator’s shaft for a wind velocity by the wind turbine. The modulation strategies for each submodule and for each leg of the modular multilevel converter were also discussed. To prove the operation of the control system, simulation results were acquired and analyzed.