H. Jouybari-Moghaddam - Student Member- Department of Electrical Engineering, Amirkabir University of Technology, Tehran
S.H. Hosseinian, - Department of Electrical Engineering, Amirkabir University of Technology, Tehran
B. Vahidi, - Senior Member, IEEE - Department of Electrical Engineering, Amirkabir University of Technology, Tehran

In order to avoid unnecessary loss of supply especiallyfor high priority loads, distributed generators (DGs) stand-aloneoperation is getting more attention. However, to ensure morereliability, the islanded distribution network must reconnect tothe grid as soon as the quality of supply from grid is refined. Asthe circuit breaker (CB) which had been opened forunintentional/intentional islanding operation is often kilometersfar from the DG, introducing a reliable method for localizedreconnection detection and proper DG control mode activationwill be an interesting issue. Such a method could be implementedvia a micro-processor based relay as a low cost alternate for theexpensive communication means required between all of the CBsthat may initiate the islanding and the DG. In this paper asuitable procedure to provide reconnection detection signal forsynchronous type DGs is presented. The procedure is based ongovernor signal processing.

Active distribution networks, micro-grid,stand alone operation, synchronous generator, reconnection, signal processing