Technical and Economic Aspects of Implementing 20 Kv Electrical Networks

Abstract

This article analyses peculiarities of technical and economic preconditions for modernization of existing 6 and 10 kV distribution electric networks by turning them into 20 kV networks. The analysis is based on 6 and 10 kV networks of one of Lviv districts, Ukraine. The features of these networks is a considerable length of 6 and 10 kV overhead lines and dynamic load growth leading to an overload of individual line sections and significant reduction of the voltage level on the buses of many consumers.

Investigation of the initial mode of maximum loads shows that technological losses of active power in 6 kV electric network are 14,8 %, and in 10 kV electric network — 9,21%, with the current overload of individual line sections and a significant decrease in the voltage levels on the substation buses. Switching the 6 kV electric network to the voltage of 10 kV can reduce the technological losses of active power of the entire 10 kV network to 7,36 %, but this does not solve the overloading of transmission lines and unsatisfactory voltage levels. Switching all investigated power network to voltage of 20 kV allows to reduce active power loss to 2,8 %, and if power network is optimized — up to 2,12 %, and voltage losses on all optimized sections of 20 kV electric network will not exceed 3 %.

Investigation of the power network modes with the condition that during next 15 years the load will be increasing, shows that the mode with 6 kV voltages cannot exist physically; switching the entire power network from 10 kV voltage to 20 kV will allow to maintain voltage losses on the buses of the most remote consumers at 3 %, and savings on electricity losses will be 48,0 %, or 4,1 million kWh.

Calculation of economic indicators shows that the return on investment for switching the studied electric networks to a nominal voltage of 20 kV is more than 15 years.