The three voltage level distribution using the 1000 V low voltage system

Abstract

The need to improve the quality and economy of the electricity distribution process has increased year by year. An interesting new innovation in the distribution network development has been the use of 1000 V (1 kV) low voltage lines together with 20 kV and 0.4 kV systems. The 1000 V low voltage distribution system gives an opportunity to answer to the demand of ever-growing need to improve the economy and quality of electricity distribution business. It is based on old principles that today are possible to be taken into use both economically and technically. The EU-legislation enables the use of 1000 V low voltage level as a third distribution voltage level between the current medium voltage network and the low voltage network. Adding the third voltage level shortens the length of the medium voltage network and diminishes the number of short branches and affects the interruption costs of the entire distribution network. In this paper the basic structure of new 20/1/0.4 kV system is illustrated. Paper presents the basics of operating and protecting the 1000 V low voltage network in boundaries given by the European standardising. Techno-economic analyses of the usability of the three voltage level distribution system are introduced as well as some case examples of the three voltage level distribution system already used in Suur-Savon Sahko distribution company located in the Eastern Finland. The three voltage level distribution system has been in use at lake district for several years. The experiences are very promising.