Research And Application Of The Intelligent Decoupling Control System On The Three-Phase Electrodes Of The Submerged Arc Furnace

Submerged arc furnace is widely used on the ferroalloy production in China. The smelting efficiency can be improved and the economic cost can be saved if the three-phase electrodes’position can be controlled well. However currently, most control ways of three-phase electrodes’position are controlled through primary current balance manually. That brings poor control effect. Therefore, the study of the three-phase arc furnace electrode position control technology is important for improving the process efficiency and reducing production costs. To this end, this paper carried out the following studies:1. To keep the temperature field in the weld pool of the submerged arc furnace balanced, the three-phase power in the weld pool must be controlled balanced. Considering the three-phase loads and the load currents for calculating the three-phase power in the weld pool can’t be measured directly, the superposition principle is used to calculate the "short net" currents and then the load currents can be calculated. The "U-I" model of the three-phase loads is established according to their own characteristics. At the same time, the electrode current-position model which can fully reflect the coupling effects among three-phase electrodes is established. Besides the model’s parameters are identified by using large numbers of field data.2. Considering the system’s strong coupling characteristic, a method analyzing the coupling effect qualitatively is proposed. Take "current change ratio" as the coupling factor, which can intuitively reflect the coupling law and coupling strength of the system; And a new decoupling control strategy based on the "most sensitive phase electrode" is proposed. By using that decoupling control strategy, it can reduce the number of electrode move and the electrodes’displacement, thereby, protect the motors, inverters and other control equipments, enhance the dynamic and steady-state characteristics of the system.3. Considering the fact that it is very difficult to establish a precise mathematical model on submerged arc furnace system, the variable universe fuzzy control which doesn’t rely on precise mathematical model is adopted. It can expand and contract the universe according to melting and redox period during the smelting process, thereby, improve control accuracy and stability. Meanwhile, design an intelligent decision and decoupling controller, which can set control cycle and dead zone depending on furnace conditions. At last, design an intelligent decoupling controller of submerged arc furnace electrode system by combining the variable universe fuzzy controller and intelligent decision-decoupling controller. The simulation results show that control effect is good. The intelligent decoupling controller is used in industrial field through PLC control program and WinCC configuration system. The tests show that its decoupling effect is good, the system is stable, there is a certain energy saving effect.66figures,5tables and66references are involved in this paper.