Enhanced models with time‐series coefficients used for electric arc furnace

Abstract

Electric arc furnace (EAF) is one of the most disturbing loads in the power system as it is highly time-varying and nonlinear. In this paper, new models based on the instantaneous EAF voltage and current, recorded from EAFs in Mobarakeh steel company in Isfahan/Iran are proposed. The focus of this paper is on developing efficient models based on the Schwarz model where three modified types are proposed. The original Schwarz model has four constant parameters. Unlike the original Schwarz model which uses invariant parameters, the time-varying nature of the arc's parameters is considered in the proposed models. The first modified model has two constant model orders and two time-varying coefficients. Additionally, to further enhance the model's accuracy, in the second modified model, six parameters include three constant model orders, and three time-varying coefficients exist. The third model uses all the original model's parameters as time-series parameters. The parameters of the time-varying model are derived using autoregressive moving average (ARMA) models. The accuracy of the proposed model is evaluated by calculating the active power, harmonics, instantaneous flicker, and short-term flicker. Finally, three MATLAB codes are provided to generate the model parameters time series.