Impact of the new electric arc furnace on the level of flicker in surrounding transmission and distribution power system

Abstract

Point of connection of Ironworks is 110 kV bus in 110/35(33) kV "Željezara 1" substation in Sisak in Croatian transmission power system. Installation of new electric arc furnace, requires increased agreed power for Ironworks from TSO. New electric arc furnace is connected on low voltage side of T3 transformer with ratio 110/33 kV. As a part of the test operation of the new electric arc furnace in Ironworks in Sisak, detailed measurements of Voltage Quality, in different operating modes of the arc furnace were performed. The purpose of the measurements was to determine Voltage Quality on point of connection of Ironworks during the test operation of new arc furnace and to determine negative influence of Ironworks on Voltage Quality according to the Grid Code of Croatian Power System. Measurements were performed simultaneously at point of connection of Ironworks and surrounding transmission and distribution power network. Measurement results show that in all measuring points flicker short-term and long-term flicker severity exceeds prescribed limits according to the Grid Code of Croatian Power System. From the measurement flicker transfer coefficients between different voltage levels were calculated and conclusion about flicker attenuation was given.