a fault analysis of dc electric arc furnaces with svc harmonic filters in a mini-mill plant

this paper proposes the most feasible solution to overcome the failure of the 2nd harmonic filter in the static var compensator (svc) which operates with the dc electric arc furnace (eaf) at gwangyang steel mill in korea. in order to investigate the causes of this failure, various measurements were carried out on the dc eaf and the main transformer at the pcc (point of common connection). it was concluded that the two causes for the failure are; the inrush current in the main transformer, and the parallel resonance between the system impedance and the harmonic filter. three solutions to suppress the transformer inrush current and another three solutions to avoid the parallel resonance are suggested. the feasibility of these solutions was verified through the computer simulation with pscad/emtdc. the most feasible solution to avoid further failures of the 2nd harmonic filter was selected, based on the estimated result for the six optional solutions in the point of performance and cost.