Segmented Energy Routing for a Modular AC/DC Hybrid System

This paper presents a modular AC/DC system with both distributed and centralized power ports for energy router (ER) applications. In each module of the described system, photovoltaic (PV) power generation units, battery-type energy storage (ES) units, and critical loads are connected to the cascaded H-bridge-organized medium-voltage (MV) DC links, with fully distributed low-voltage (LV) DC power ports. Copies of modules share the centralized load bus and interact with an MV AC grid in parallel. Hybrid-power-port (HPO) assigns flexibility to the system but makes energy routings a necessity for stable operation. In this paper, a segmented energy management strategy for the HPO-ER is proposed. In terms of the grid-side power transferring, the system ratings are intentionally designed to match significant power imbalance. Focally, a segmented energy management strategy is proposed in order to realize fully autonomous energy routing involving MV AC grid, distributed PV generations, distributed battery storages, and LV load. The system is proved to be stable by using the derived impedance-based model considering the interaction between power blocks. The feasibility of the topology and control strategy is also verified through software simulation, laboratorial hardware prototype experiment, and hardware-in-the-loop (HIL) emulation.