Online Energy Sharing for Nanogrid Clusters: A Lyapunov Optimization Approach

Nanogrid (NG) cluster (NGC) has the potential to act as one type of basic structure for the future low voltage distribution networks. In this paper, an online energy sharing method is proposed for improving the self-sufficiency and photovoltaic (PV) consumption of NGC. First, a hybrid cyber-physical peer-to-peer (P2P) energy sharing framework is proposed, which is a combination of P2P physical system (i.e., NG-to-NG) and client-server cyber system (i.e., NG controllers-central controller). Moreover, an energy sharing strategy with the classification of energy exporting and importing NGs is designed. Considering the stochastic features of PV energy and end user load, an online optimization model and algorithm is formulated based on Lyapunov optimization, as to maximize the self-sufficiency and guarantee the stability of energy storage queues. Finally, in a case study using the realistic data from the residential community, numerical experiments show the effectiveness of the proposed method in improving the self-sufficiency of NGC.