System identification of a three-phase submerged-arc ferrosilicon furnace

A 36 MW submerged-arc ferrosilicon (FeSi) furnace is modeled using the technique of system identification. The main purpose of the modeling is for the simulation and evaluation of different control schemes. In particular, the part of the system associated with the control of the three-phase electrode currents, which is done by positioning of the electrodes, is examined. Data were collected at Icelandic Alloys Ltd., using experiments conducted mostly in open loop. The positioning of electrodes responding to control signals was estimated and modeled using measurements in closed loop. Data collection for the disturbance identification was done by keeping the three electrodes fixed and recording the currents. A first-order autoregressive (AR) model was used to model the disturbance environment. Different ARX MIMO models were tried using several model orders, combinations of inputs, and input delays. The results obtained indicate that the simple linear models developed include all the critical factors needed in a simulation of different electrode position based control schemes for the electrode current control of the furnace.