Coordinated Hierarchical Control Strategy for Islanded ac/dc Hybrid Microgrids

Abstract

To meet future practical needs of smart grids, constructing hybrid ac&dc microgrids with the two-type sub-grids becomes more realistic and urgent. However, in the existing literature, it is rare to see the joint controls of these sub-grids in islanded hierarchical control architecture. To this end, a coordinated hierarchical control strategy for this kind of hybrid microgrid has been presented in this paper, where both sub-grids are equipped with primary and secondary controllers. Using the proposed strategy, the power flows can be autonomously shared and deviated bus voltages can be fully restored. The control performance and stability of the overall microgrid system have been ensured to address different ac/dc load changes. Comprehensive simulation studies have verified the validity of the proposed strategy for hybrid microgrids.