Avoiding MV distribution system blackout by using rocof relay

Generation systems in Riau Islands Province of Indonesia consist of many diesel generators, some of them own by PLN and the others are third party properties rent by PLN. Powers of these generation systems are delivered to customers via 20 kV overhead distribution lines. Generation shut down events in the last year that have made inconveniency due to unavailability of electricity supply to customers. Frequent faults on these overhead distribution lines, especially on heavy load feeder, may cause some generators trip, especially on third party generators, even feeder protection already trip firstly to clear the fault. The governor of the third party generators set in load control mode. In order to avoid system blackout, rocof relays are introduced in this system. This paper describes how to maintain the system that consists of different type of governor control modes.