Experimental study of effects of electrical arc furnace on electric network and computer aided modeling

During the recent years, with its increasing steel production, Turkey has succeeded becoming one of the ten biggest steel producer countries in the world. In Turkey, approximately 71.3% of the steel produced in Turkey is producing with the help of Electric Arc Furnace (EAF) facilities. EAF's have significant advantages such as high melting and low production costs. However, due to their nonlinear characteristics, they cause significant power quality problems in electrical networks. In this study, the power quality problems caused by 60 MVA EAF load, which is located in SİDEMİR facility, have been experimentally investigated. Harmonic effects have been evaluated with the help of the Electromagnetic Transient Program (EMTP) using a phase equivalent of the electrical system feeding the EAF load. Suggetions to improve of the power quality problems caused by EAF 60 have been presented by comparing experimental measurement results and EMTP analyzes. Suitability of the time-domain arc models which has been presented in literature for the definition of electrical arc have been examined with the arc characterization obtained from the experimental data and the curve fitting methods using Matlab Curve Fitting Toolbox and a new time domain arc model have been developed to identify the electrical arc for EAF's. It is seen that the developed new time domain model describes the operating characteristics of EAF furnaces better than the models presented in the literature. It has been shown that the three-phase simulation model using this arc model can be used with high accuracy to identify power quality problems caused by the EAF. As a result of the experimental studies carried out and the simulation done it has been identified that SVC systems cause even harmonics, and serial reactor application is not suitable for the current system. The transformers must be protected with differential differential relay and It has been determined that when synchronous compensation and SVC compensation are used together, voltage harmonics occurring at the beginning of melting can be reduced. According to the probability theory, current and voltage deviations smaller than 5% in the present network.