A new service restoration algorithm for ungrounded distribution system

Fault section isolation and service restoration are very important for distribution automation system (DAS). A progressive protection method has been adopted in Japan for the line to ground fault. But this method has some drawbacks that the customer would experience outage time and that the usage factor of the feeder is not over 50%. This paper proposes a new algorithm for line to ground fault section isolation and service restoration in ungrounded distribution system. When the single-connection feeder is changed into multi-connection feeder, the outage time can be decreased, which obviously makes the usage factor of the feeder increase. And the proposed algorithm has been successfully verified in a model distribution system.