Energy management system (EMS) for real-time operation of DC microgrids with multiple slack terminals

DC microgrid with multiple slack terminals has higher system reliability in case of slack terminal outage and communication failure. However, system bus voltage deviation from the nominal value and power sharing error are the main drawbacks of the droop-based distributed control. A three-level Energy Management System (EMS) is proposed in this paper to ensure both fast response and accurate control of the multiple-slack-terminal DC microgrid. All Energy Storages (ESs) are scheduled to operate in voltage regulation mode in level I control. The bus voltage regulation and power sharing among ESs are realized based on local bus voltage autonomously. In level II, bus voltage restoration and power sharing compensation are implemented to eliminate voltage deviation and power sharing error accordingly. Level III control takes the constraints of ESs' power capacity and energy capacity into consideration. Load shedding and generation curtailment are to be activated based on the real-time system net power and ESs' State of Charge (SoC). Case studies based on MATLAB simulation were carried out to verify the effectiveness of proposed methods.