Once the DG has been separated from the utility system, after
interconnection protection operation, the intertie must be restored.
Two DG tripping/restoration practices are widely used within the
industry. The first restoration method (case 1) is used in
applications where the generation at the distributed generation
facility does not match the local load. In these cases,
interconnection protection typically trips the DG breakers, as
illustrated in Fig. 7. When the utility system is restored, the
distributed generators are typically automatically resynchronized.
Many utilities require a synchrocheck relay (25) at the main
incoming breaker to supervise reclosing as a security measure to
avoid unsynchronized closure. The synchrocheck relay is
generally equipped with dead bus undervoltage logic to allow