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With the increase of the number and geographic
dispersion of distributed energy resources (DERs), the microgrid (MG) has
become scattered along with the higher complexity of control and communication.
This paper proposes a two-level regulation strategy to achieve the local
objective of frequency regulation and power sharing as well as the global
objective of economic operation in the real time for the scattered MG. Firstly,
the MG integrated with multiple DERs is partitioned into severalnanogrids
(NGs) such that DERs connecting on the same feeder are grouped in the same NG for
the efficient and cost-effective communication and control. Thenin the NG
level, the total power mismatch of the entire MG can be learned and an optimal
incremental cost can be agreed by each NG through the fastest distributed linear averaging (FDLA)
and discrete-consensus algorithm, respectively. In the DER level, a cost-driven
droop gain is developed to indicate the willingness of each DER in the NG to
participate into the frequency regulation service. The pinning-based protocol
is formulated to regulate the frequency and meanwhile enable the proportional
power sharing among DERs based on the economic droop function. Case studies
satisfactorily demonstrate the effectiveness of the proposed regulation
strategy for the economic frequency regulation in the tested MG.