Abstract

Series-cascaded microgrid topologies are attracting interest due to their flexibility of control and the reduced number of power conversion stages that are required for low power applications. Existing studies on series-cascaded microgrids have focused on combinations of either dispatchable or non-dispatchable DGs. However, a more practical scenario, in which dispatchable DGs, non-dispatchable DGs and storage elements are incorporated, has not been investigated to date. This hybrid structure poses several operational challenges, since the control frameworks for each microgrid source generally conflict with one another (i.e. droop control for dispatchable DGs, current regulation mode for non-dispatchable DGs and high level (dis)charging regimes for storage elements), which can adversely impact on the autonomous capability of each source. This paper investigates the operation of a hybrid series-cascaded microgrid incorporating diverse DG sources. The proposed topology and control strategies enable smooth operation of the nondispatchable DGs and storage elements in accordance with their preferred operating modes without relying on a centralized control system. The performance of the proposed hybrid series-cascaded microgrid has been validated in simulation for a broad range of loading conditions.