A Time-Domain AC Electric Arc Furnace Model for Flicker Planning Studies

Abstract

A time-domain model of an AC electric arc furnace (EAF) was developed for power system (flicker) planning studies. The proposed model was implemented in the Electromagnetic Transient Program (EMTP), and it focuses on the behavior of the EAF during the early stages of the melt cycle, thus providing an accurate prediction of the short term flicker created by the EAF, specifically Pst99%.ldr The primary advantages of the proposed model over existing models are: 1) it uses system data that is readily available to the planning engineer; 2) it is a three phase model and can accurately model imbalance and predict flicker at the point of common coupling (PCC) as well as remote buses in the power system; and 3) its accuracy has been verified using synchronized flicker measurements of an actual EAF. Existing time-domain EAF models that are used in flicker planning studies require measurement or statistical data that is difficult to obtain during the planning stages of a project. Frequency domain methods are a popular means of estimating the flicker created by an EAF; however, when these methods are used in flicker planning studies, the operational uncertainty of the EAF introduces error into the calculations. Also, in many cases, frequency domain methods struggle to accurately predict the flicker level at buses remote from the PCC. Thus, a time-domain EAF model which can accurately predict Pst99% at points of interest and uses readily available system information is needed. The following paper describes such an EAF model. Validation of the proposed model is performed by comparing simulation results with flicker measurements of an actual EAF that were time synchronized using Global Positioning Systems (GPS).