The paper deals with the main results of comparative analysis of static var compensator (SVC) control modes, which are used in electric power system of high and ultra-high power electric arc furnaces (EAF). Traditional SVC control modes designed for implementation of zero reactive power consumption of the steel-smelting complex and voltage stabilization at the common connection point of EAF and SVC are considered. In addition, this paper describes the developed mode, which maintains a constant active power of an electric arc furnace. The effects of supply main parameters and SVC control modes on the EAF electrical characteristics are investigated with a mathematical model of the EAF-120 and SVC-100 MVAr steel-smelting complex developed in the Matlab’s Simulink application. Thus, advantages and disadvantages of the discussed SVC control modes are determined and main recommendations for their application are given.