Wireless based real-time power coordinated control strategy for a DC microgrid

In a dc microgrid, the bidirectional dc-ac converters are usually operated as a utility interface to control the dc bus voltage and ensure the power balance within the system. In the case of grid failure, power limiting or malfunction condition for dc-ac converters, the dc microgrid will lose its power balance unit. At that time, the distributed generations in dc system will change their operation mode to maintain the dc bus voltage through energy management control. However, this kind of control strategy may not be able to implement realtime power balance due to communication delay and may lead to system collapses in some extreme cases. This paper proposes a wireless based real-time power coordinated control strategy, which is a decentralized control strategy without extra communication link and makes it a viable option for plug and play. In this strategy, each unit in dc microgrid not only can realize smooth transition between different operation modes upon the dc bus voltage signal, but also can adjust its droop curve adaptively according to operation condition. Therefore, the voltage regulation, power balance and power sharing among different sources can be guaranteed. Finally, the validity of the proposed control strategy is confirmed by experiments based on a typical low voltage dc microgrid with simulated dc source, dc-ac interface converters and dc load.