Hierarchical control of DC microgrids robustness and smartness

This paper investigates the hierarchical control of DC microgrids. Compared to AC microgrids, DC microgrids encounter complicated converter-level control, and simplified system-level management. To address these characteristics, a new three-level control hierarchy is introduced. The converter control level encapsulates sophisticated converter topologies and inner control loops into a black-box representation. The voltage coordination level uses DC voltage signals to coordinate both static and transient power sharing. The energy management level optimizes the power flow and power quality in a broader scope through communication. This architecture lowers the focus of control to bottom levels. More functions are allocated to the converter control and voltage coordination levels. They can maintain basic microgrid performance with fully local control, thereby ensuring reliable power supply in case of communication failures. Moreover, taking advantage of DC microgrids' simplified system-level operation patterns, the energy management level uses straightforward algorithms to achieve intelligent functions. As a result, this architecture achieves both robust and smart control by exploring DC microgrids' critical features.