The Development of the Swedish 400-Kv Network

The main objective of the Swedish 400-kv system is to transmit a large amount of energy from the hydropower resources in the north of the country to the consumers in the south. The average distance is 400 to 500 miles, whereas the distance between the extreme points is 850 miles. Today 3,800 mw is transmitted. The main problems are stability and insulation co-ordination. Bundled conductors and series capacitors in the power lines and low reactances in alternators and transformers are used to improve stability conditions. The insulation strength can be gradually decreased with the growth of the system because of the lowered internal overvoltages. Transmission capacity of individual power lines and unit sizes of transformers are increased. Service reliability is excellent.