Evaluation of of operating High Power Electric Arc Furnace from set of generators

Abstract

Electric arc furnaces (E.A.F) are used in most countries of the world to melt scrap iron. The capacity of these furnaces ranges between 20-100 (MW). Smaller furnaces are mostly fed from 33-66 (KV) networks, while larger furnaces are fed exclusively from 230-150 (KV) networks. Due to the lack of energy sources in the local electric grids, some researchers and electric grid operators are considering the possibility of using independent turbine-generator sets, which act as islands to feed electric arc furnaces. In this paper, the work of electric arc furnaces was analyzed, based on real values ​​of an electric arc furnace with a capacity of 60 (MVA), and the specifications of real transformers and reactors used in such furnaces were also adopted.

In the first step, the system was simulated when operating from the public network 230(KV), in order to show the reality of regular operation and to verify model and compare them with the real EAF operation values. Then, independent turbine-generator sets of different capacities (60-90-150) megawatts were used, connected to the existing furnace network. In each case, the results of feeding the furnace with these generators were analyzed. Results show the impossibility of feeding electric arc furnaces from independent generating sets, no matter how high the power of these generators is, and it was found that the values ​​of current and voltage arising in the generators are very large and will lead to apply a large electromagnetic torque on the axes of the rotating parts and thus damage and break them. The voltage of the coupling point will also rise and the system will enter the non-realistic safe operation.