Utilizing the ring operation mode of MV distribution feeders MV networks in Finland: Neutral isolated and compensated systems Networks are traditionally used radially but constructed partly meshed Open-points of the network are often at the remote controlled disconnector stations The perspective of the study Ring connection of two feeders fed from the same primary substation When the ring-connection is advantageous and what the preconditions are?

Utilizing the ring operation mode of MV distribution feeders - improved preconditions Increased breaking capacity and reduced operation times of SF6-insulated switch-disconnectors Modern feeder terminals Economic voltage and current sensors available Measurements and state estimation of loads

Conclusions Benefits: Optimal power flow between looped feeders Reduced maximum voltage drop Reduced power losses Possibility to determine the distance to earth faults neutral isolated and compensated systems Option for dynamic use of ring connection according to seasonal load variations Option to increase the integration capacity of distributed generation at existing network

Conclusions Major drawbacks: More complicated feeder protection Such as autoreclosures of overhead line feeders Severity of voltage sags are increased compared to radial operation mode Especially systems including mainly overhead lines