Adaptive control of the electric arc furnace electrodes using Lyapunov design

In this paper, an adaptive controller is designed to control an Electric Arc Furnace (EAF) electrode. For this purpose, a nonlinear model for EAF is considered. Piecewise-linearization method is used and based on the Lyapunov´s method an adaptive control rule is achieved. EAF different operating conditions are considered and in each condition the system response by using proposed adaptive controller is compared with its response with PI controller which is usual controller for EAF. At first minutes of melting process, scrap surface changes suddenly. When the scraps are melted, the distance between electrode tip and melted material surface is considered to change sinusoidal containing the white noise. Also the effect of noise in current measurements is investigated. In all conditions the controller should change the electrode position so that the effective value of arc current remains constant. Additionally several conditions that don´t occur in actual EAF are simulated to compare the response of those nonlinear systems that have transfer functions similar to EAF, with adaptive and PI controller.