A comparative study of AC/DC converters for high-power DC arc furnace

Today, dc arc furnaces are supplied by thyristor rectifiers. Because of the phase control strategy on the rectifiers, the arc voltage swings induce large reactive power variations on the power network and a static VAr compensator (SVC) or a static synchronous compensator (STATCOM) is always added to avoid flicker effect. In this paper, the authors present a new control strategy which suppresses the flicker effect and increases the furnace productivity. To supply the dc arc furnace, the ac/dc converter is based on diode rectifiers and choppers with a constant power control strategy. Consequently, the ac/dc converter can operate without a STATCOM or an SVC. To evaluate the gain in flicker and furnace productivity, simulations are done with Matlab software. These simulations take into account arc voltage measurements on a 100-MW dc arc furnace and allow for comparison of the different solutions.