Distributed Voltage Control and Power Management of Networked Microgrids

In this paper, a distributed control scheme is proposed for voltage control and power management of coupled microgrids (MGs). The control scheme is implemented in a two-level structure. In the primary level, a voltage–current droop controller is adopted in the <inline-formula> <tex-math notation="LaTeX">$dq$ </tex-math></inline-formula> reference frame to facilitate proportional load sharing among the distributed energy resources (DERs) with fast dynamic response. A novel distributed secondary control scheme is introduced to regulate the power exchange among MGs and restore the average voltage to the nominal value. The secondary controller is comprised of a network of control agents interconnected through low bandwidth communication links. Each control agent alters the offset of <inline-formula> <tex-math notation="LaTeX">$d$ </tex-math></inline-formula>- and <inline-formula> <tex-math notation="LaTeX">$q$ </tex-math></inline-formula>-axis droop characteristics to change the current output of the DERs within each cluster until the current exchanges among the clusters are regulated at the set points and the average voltage is restored to the nominal value. If the load of an MG cluster is increased above its total generation capacity, the secondary controller alters the current exchange among the clusters to prevent overload. Simulation and experimental results are presented to demonstrate the efficacy of the proposed method.