Identification of an electric-arc furnace electrode-control system

The dynamic performance of a 135 tonne 35MVA 3-phase electric-arc furnace with a Ward¿Leonard drive is investigated. The design of experiments and collection of data from a production furnace are discussed, and the arc-discharge coefficient and a nonlinear representation of the arc impedance are identified. A difference equation representation of the arc-furnace electrode-position controller is also identified using a generalised least-squares estimation technique with operating data from a production furnace. The identified model is compared with a model derived from the electromechanical properties of the furnace, and interaction of the regulator operating under impedance control is investigated. Adaptive control and the design of an improved control system using the identified models are briefly discussed.