Permanent Closed-Loop Operation as a Measure for Improving Power Supply Reliability in a Rural Medium Voltage Distribution Network

Abstract

Power supply reliability is one of the critical elements of power quality. Its improvement in medium voltage distribution systems in urban areas is typically achieved by cabling. Unfortunately, this approach is often too expensive to be applied in rural areas. One of the possible alternative solutions that can be used in rural medium voltage distribution networks is permanent closed-loop operation. It requires the introduction of additional reclosers with properly parametrized protection relays enabling directional protection. This paper focuses on the case study performed in the 20 kV rural distribution network of Elektro Celje d.d.. Two feeders, where the reliability of the power supply was low, were analyzed. Results of techno-economical evaluation eliminated cabling as a viable solution. The permanent closed-loop operation was selected and implemented after proper placement and parameterization of relays with directional protection functions. The results of two years operation in permanent closedloop arrangement of feeders show substantial improvement in the reliability of power supply.