1. 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?

2. 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

3. 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

4. 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