Autonomous DC-Bus Voltage Regulation in DC Microgrid Using Distributed Energy Storage Systems

Abstract

A DC microgrid has many advantageous features, such as low power losses, zero reactive power, and a simple interface with renewable energy sources (RESs). A bipolar DC microgrid is also highlighted due to its high-power quality, improved reliability, and enhanced system efficiency. However, the bipolar DC microgrid has high DC bus voltage fluctuation due to the load power unbalance between the poles. Therefore, this paper analyzes the DC bus voltage fluctuation that can occur in the bipolar DC microgrid. An autonomous grid voltage regulation method is introduced to regulate the DC bus voltage of a bipolar DC microgrid using distributed energy storage systems (ESSs). The proposed grid voltage regulation scheme using the distributed ESSs could regulate DC bus voltage in real time, regardless of the structure of the DC microgrid without external communication. Lastly, experimental results using a lab-scale bipolar DC microgrid prototype verified the proposed method.