Transient analysis of road tunnel power system

Abstract

The main tasks of Statens Vegvesen is to plan, build and maintain the roads of Norway. Tunnels are included as a part of this task. Due to expected changes in usage patterns and needs, the Norwegian authorities decided to adapt to the European model the design of low voltage networks. The backup power system is one of the most important parts of the installation and presents an independent source of electrical power, which is being used as external power supply in case of loss of regular supply. Nowadays most of the Norwegian networks in tunnel for backup power supply system are built up as a 400V TN/230V IT network, using step-down transformer. A transition to the pure TN system is desired. Backup power system is a complicated system based on usage of uninterruptable power supply (UPS), which has different variations and challenges. That is why it is interesting to investigate how the existing installations of backup power system can be converted according to the new requirements.