A Comprehensive Control Strategy for Multibus Nanogrids With Power Exchange Between Prosumers

Microgrids/nanogrids of prosumers must be able to adapt to new business opportunities related to energy trading. Therefore, highly accepted hierarchical control strategies should be modified to allow deliberate energy interchange among prosumers, even when the microgrid they are integrated in, operates islanded. This is the main contribution of this paper, as energy exchange between prosumers is rarely addressed when they are islanded from the main grid. This work proposes a comprehensive hierarchical control strategy for a multibus nanogrid of prosumers, each of them having photovoltaic generation, battery energy storage systems and loads, in such a way that different voltage and power setpoints for each prosumer allow such energy interchange. Power flow inside the nanogrid is controlled to guarantee the technical feasibility of the obtained setpoints. The proposed control strategy is defined and experimentally validated in both islanded and grid-connected modes, by means of a laboratory-scale prototype. In addition, a smooth transition between the two modes is demonstrated. An adequate capability of the power converters to follow setpoints is proved, with acceptable transient behavior.