Abstract
The networking of geographically-close microgrids (MGs) offers additional operational flexibility for realizing the benefits of various DERs. The failures of CMC (central master controller) or master controllers (MCs) in certain MGs due to natural or human-made disturbances might impede the performance of networked MGs and even compromise the system security. This paper proposes a unification scheme to restore the MG function in a networked MG system with failed CMC and certain MCs. In the unification scheme, failed CMC delegates its control authority to certain MCs and failed MCs relinquish their control responsibilities to designated MCs in adjacent MGs. The neighboring functional MCs are accordingly allowed to take the lead for managing the operations in malfunctioning MGs. The unification control signal provided by the designated MCs is imposed on pinned DERs and propagated among remaining DERs in the MGs with failed MCs, which reduces the communication complexity among MGs significantly. The proposed unification scheme is expected to achieve desired control performances even when the available communication resources are not sufficient to maintain continuous unification control signals in networked MG system. The effectiveness of the proposed unification scheme is validated by the time-domain PSCAD/EMTDC simulations of two networked MG systems.