Energy storage requirements of dc microgrids with high penetration renewables under droop control

• Energy storage is a important design component in microgrids.
• Distributed droop control enables a completely decentralized control architecture.
• Energy storage requirements are minimized with the optimal choice of droop settings.

Energy storage is a important design component in microgrids with high penetration renewable sources to maintain the system because of the highly variable and sometimes stochastic nature of the sources. Storage devices can be distributed close to the sources and/or at the microgrid bus. In addition, storage requirements can be minimized with a centralized control architecture, but this creates a single point of failure. Distributed droop control enables a completely decentralized architecture but, the energy storage optimization becomes more difficult. This paper presents an approach to droop control that enables the local and bus storage requirements to be determined. Given a priori knowledge of the design structure of a microgrid and the basic cycles of the renewable sources, the droop settings of the sources are determined that minimize both the bus voltage variations and overall energy storage capacity required in the system. This approach can be used in the design phase of a microgrid with a decentralized control structure to determine appropriate droop settings as well as the sizing of energy storage devices.