Network voltage distortion by arc furnace and its mitigation
Electric arc furnace (EAF) is the most dangerous type of load for power systems. It causes different kinds of distortion due to its frequently variable character. Nowadays there are different types of arc furnaces. This article is devoted to medium capacity EAF (with operation capacity less than 10 tons). Distortion of 6 kV power system by medium size EAF (3 tons capacity, 3.2 MVA furnace transformer) and its impact on medium voltage systems are considered and analyzed. Medium and high capacity EAFs are compared. Based on the presented experimental results it has been concluded that the main distortion of medium capacity EAF is a flicker. The values of the short-term flicker and a long-term one are 12 times higher than their permissible ones. From the viewpoint of flicker value reducing a mitigations technique is analyzed. Two ways of mitigation: static thyristor compensator and static synchronous compensator are compared for usage with medium capacity EAF. It is shown that the second way is more perspective.