Vector Polynomial Electric Arc Furnace Models

Abstract

Electric arc furnaces (EAFs) have nonlinear and time-varying voltage-current characteristics which cause voltage flicker and harmonics. An accurate EAF model is required to study its negative power quality impacts and the possible solutions. Although there are many EAF models, most of them are single-phase models. Few others consider the three-phase modeling of the EAF feeding system. However, three arcs with independent mathematical equations are used. There is not much distance between the three arcs; one end of the three arc columns is the shared molten bath. So, the voltage and current of each arc depend on the electrical quantities of the other two arcs, which have been neglected in almost all previous EAF models. This paper presents two EAF models where the arc voltage/current is a polynomial function of three-phase arc current/voltage and their derivatives. Many of EAFs' actual records at the Mobarakeh Steel Company in Isfahan, Iran, are used to develop the proposed models. The best model orders are attained using error indices based on actual data. The models' parameters are calculated every half cycle based on the actual records. Then, they are considered time series and modeled with ARMA models to be reproduced using the enclosed MATLAB codes.