Control Technology for T-type Three Level Power Conversion System Under Non-ideal Grid

摘要

Network voltage unbalance would cause distortion of grid-connected current of power conversion system and increase its harmonic contents, and in worse conditions, devices would be disconnected to protect, which would affect power grid. To guarantee stability of system control, taking balance grid-connected current exported by power conversion system and device networking during failures as the control objectives, the essay put forward control strategies for two-stage type and T-type three-level power conversion systems in non-ideal gird conditions. By controlling AC side negative current, guaranteeing that power conversion system can steadily networked under the condition when power grid is imbalanced. To verify the control strategies, the essay had simulation and experimental verification at last to fully prove validity of the strategies in non-ideal conditions.