Reliability-based planning in rural areas; goals, methods, prioritization, and follow-up at Fortum Distribution

In 2005 Fortum Distribution initiated a reliability improvement program in Sweden, denoted SäkraNät. Since then, more than 3000 km of mainly medium voltage overhead lines has been converted to aerial and/or underground cable. In addition, feeder automation and remotely controlled disconnectors has been installed in order to quickly sectionalize faults and restore power upon an interruption. The goal of this paper is to describe the approach Fortum has been using in Sweden to improve reliability in rural and semi-rural areas. The planning process, beginning with goal-formulation, identification of optimal solutions and methods to improve reliability, prioritization and follow-up is described. All finalized reliability projects are followed up and its effect on, e.g., System Average Interruption Duration Index (SAIDI) is measured by comparing recent interruption statistics from historical. The benefit and cost-efficiency of the investments are evaluated and knowledge is transferred back to the planning department for consideration into future projects.