  This paper proposes a novel hierarchically coordinated energy management
system (EMS) for a regional community (e.g., residential area, campus,
industrial park, etc.) comprising multiple small-scale microgrids (MGs) (e.g.,
houses, buildings, etc.). It aims to minimize the total operational cost of the
MG community and maximize the individual benefit of each MG simultaneously. At
the local level inside each MG, with the detailed modeling of various energy
resources including photovoltaics (PVs), energy storages (ESs), electric
vehicles (EVs) and dispatchable loads, the individual optimization problem is
formulated as a mixed-integer linear program (MILP). Local EMSs makes power
dispatch decisions for all the controllable units to minimize the operational
cost in individual MGs. At the community level, a novel pairing algorithm is
proposed to explicitly find the MG pairings with surplus and deficit. The
community-level EMS employs the pairing algorithm to determine specific power
exchanges among MGs and minimizes the energy transactions with the upstream
grid. The operational cost of each individual MG is further reduced by
additional economic benefits procured by the community-level EMS. The proposed
method has distinguishing advantages on modeling generality, computational
complexity and privacy protection, and its performance is verified by the
simulation results.
