Research On Control Method For Electrode Regulating System Of Electric Arc Furnace

The electric arc furnace (EAF) is crucial equipment in the steelmaking process. In the steel-making process, it is requested that the EAF should have characters of low power consumption, high thermal efficiency, little grid harmonic disturbance etc.. So the electrodes should move fast and accurately in accordance with the requirements of smelting process. Thus, based on conditions of production to adjust the position of the electrode quickly and accurately, it has a very important significance on efficiency of the EAF.The main purpose of this thesis is to use intelligent control algorithm to control the movements of EAF electrodes, and then to improve steel quality and equipment utilization, and to reduce power consumption. This can not only have better effect on digestion and absorption of foreign equipment and technology, but also is important to develop high-performance electrode automatic regulator for the steel-making to improve quality, reduce energy consumption. Owing to that the EAF electrode regulator system has nonlinear, delay, random characters, this thesis uses appropriate control algorithm to control Electrode regulator system, making the electrode regulation system has good dynamic performance at all stages in refining.In this thesis, the components of impedance control system of the SIMATIC are analyzed. And for that the traditional PID control can not solve the conflicts of dynamic quality and steady precision fundamentally, the parameter self-tuning fuzzy PID control is applied to the EAF electrode regulator system. The designed controller can adjust parameters according to changes in arc current in real time, and improve the system performance and robustness of the regulation.Based on that the system architecture of sliding mode control is varied with working condition, the sliding mode control is used in EAF electrode regulator system. For the output of sliding mode controller exists the chattering problem, a dynamic sliding mode controller is designed. The dynamic sliding mode control can not only make the system has better dynamic performance and excellent tracking characteristics, but also effectively solve the system chattering problem. As arc current fluctuation and uncertain disturbance in the melting period are comparatively large, it is hard to sum up complete control rules. Based on analysis of sliding mode control method, the fuzzy sliding mode control is used in EAF electrode regulator system. It not only can reduce the system error that caused by the uncertainty of the system, but also enhance the system against internal disturbances and external disturbances. However, the output of the controller is still existed some chattering.For the output of fuzzy sliding mode controller exists the chattering problem, an adaptive fuzzy sliding mode controller is designed. Based on principle of sliding mode variable structure, the adaptive fuzzy sliding mode controller makes the switching between fuzzy control and adaptive control. Then the designed adaptive fuzzy sliding mode controller can meet the technological requirements of various smelting period. It makes the system has a good tracking performance, and it can enhance the system’s rapid and robust. It gives a great help for the future development of the intelligent control system of EAF.