Optimal control of static VAr compensators in power supply systems with electrical arc furnaces

摘要

Throughout the world, steel is melted in high-power electrical arc furnaces. Such furnaces, fed by either direct or alternating current, have power ratings of more than 100 MW. The operation of AC electrical arc furnaces causes system perturbations in the supplying network due to unbalanced fluctuations of active and reactive power in the three-phase system lines and due to the non-linear V-A-characteristic of the electrical high-current arc. Consequently, the decrease in power quality may interfere with power grid operation. In the majority of cases, inadmissible distortions, unbalances and highly dynamic fluctuations of system voltage must be avoided by using compensators. Requirements for such compensators are: Supply of reactive power (base load) for limitation of voltage deviations. Filtering to keep voltage distortions within permissible limits. Controlled supply of unbalanced reactive power for mitigation of impermissible voltage fluctuations in association with flicker and time varying unbalances.