Grid Friendly Supply of Nonlinear Dynamic Loads by a Scalable Hybrid Multilevel Converter

Abstract:
European steel industry is currently facing challenges driven by stricter power quality requirements. Historically, utility requirements have been satisfied with the use of compensators (SVCs or STAT-COMs) connected in parallel to electric arc furnaces (EAFs), to correct the power factor and reduce harmonics, flicker, and unbalance. To achieve maximum power quality performance and furnace productivity improvements, a series-connected modular multilevel converter system for directly feeding EAFs has been developed. Thanks to the new topology of the converter front-end, one third of the IGBT submodules of the rectifier can be replaced by diode stacks, with positive impact on size and cost.