Restructuring of the high-voltage system in a city-effects on the 10 kV system configuration and system operation

Various installations in a 60/10 kV city network have grown old as the system has expanded over the years; this leads to high maintenance and inspection costs. There is so far no other way of assuring the reliability and availability of supplies. Despite substantial support in the form of energy-saving measures implemented by the supply utility (and the resulting general slowing down of growth), there will be no alternative but to renew these installations. Further factors such as the closing down of a power plant (for reasons of environmental protection) necessitate additional expansion measures. The authors analyse the existing supply situation and report on restructuring in the 10 kV network and on the resultant possibilities offered by an expansion variant with 110/10 kV. The authors also describe how isolated installation renewal, together with coordinated practical planning of the medium and high-voltage levels can be the first step in building up a modern supply system for the future