Feedback control system for the impedance control of an electric arc furnace

摘要

A feedback control system for the impedance control of an electric arc furnace having at least one electrode, a hydraulic electrode actuator for adjusting the electrode. The actuator is adapted to be supplied with hydraulic fluid through a control valve. The furnace further includes a controller, which is connected to the valve actuator for the control valve, and impedance signal generator for delivering impedance signals to one input of the controller and a setpoint signal generator for delivering a setpoint signal representing a desired impedance to another input of the controller. In order to prevent non-permissible electrode oscillations in such a feedback control system it is proposed to provide a correcting stage for correcting the controller gain and to provide a correcting signal generator for delivering to the correcting stage a signal which represents the controlled-system gain and which causes the correcting stage to change the controller gain in a sense which is opposite to a detected change of the controlled-system gain.