Energetically optimized control of an electric arc furnace

The control concept described here is based on an existing control system for three phase arc furnaces that uses the impedances of the three phases as control variables. It calculates the impedance set points in such a way that the electrical energy is optimally transferred into the scrap without damaging the furnace vessel. To keep the abrasion of the furnace vessel as small as possible the temperatures of the water cooled panels are measured. With a fuzzy algorithm the temperatures of each cooling panel and their time gradients are transformed into a so-called abrasion signal, which is the controlled variable of a superior control loop. The control concept was tested on a 50 t three-phase arc furnace. Exemplary results are presented.