Line loss optimization based OPF strategy by hierarchical control for DC microgrid

DC micro-grids are considered as a friendly way to integrate renewable energy resources as well as distributed energy storage systems. With high penetration of power electronic converters in DC micro-grids, the control strategies of DC micro-grids can be very flexible. However, the line loss is relatively high at the same time. Thus, a proper optimal power flow (OPF) strategy is needed for DC micro-grids to minimize the line loss. Different from OPF for conventional grids, OPF for micro-grids should not require prior knowledge of grid structure and line impedance because power sources and loads may have frequent reconfiguration in grid architecture and the extendibility of the grid needs to be taken highly into consideration. In this paper, a control strategy for OPF in DC micro-grids is proposed. It is based on conventional hierarchical in DC grids with low bandwidth communication. The key point is an improvement in the secondary control strategy. The proposed OPF strategy needs neither knowledge of grid structure nor operating condition. A 400V microgrid simulation model is presented to verify the proposed method.