Protection relay coordination on ring-fed distribution network with distributed generations

Distributed generation converts distributed resources such as wind, solar, and bio-mass into electrical energy. A successful criteria to make it profitable is a secure and reliable utility interconnection. The conventional distribution protection is traditionally designed for one supply source. In a distribution network with distributed generation, two or more sources will feed to one fault causing mis-coordinated relay operations resulting in lower supply reliability. This paper presents the time coordination method which can coordinate the overcurrent relays to protect the ring-fed distribution network with distributed generations. The results show that the optimized relay settings can improve the supply reliability especially in distributed generation cases.