Study On Intelligent Control Technique For The Electric Arc Furnace ElectrodeRegulator

In the recent years, China has made prominent achievements in steel industry. Steelproduction amount rise sharply, the level of technology and equipment improves rapidly, thedevelopment of the steel smelting in China is an important sign of the industrialization andtechnology progress. Face the realities of the low scrap steel utilization rate and power lacks，energy-efficient modem EAF should be developed to achieve high efficiency production,which is vital to promote the sustainable development of our country’s electric arc furnacesteel industry under the new situation.EAF steelmaking is an industrial process that using arc as heat source to make scrapmelting gradually, the arc are generated from the short circuit between three-phase electrodeand metal scrap when they are moving up and down. Three-phase electrode must adjust therelative distance between the electrode and furnace burden according to length of the arc, toensure the arc length stable and melting burden under the best thermal efficiency. Sinceelectric arc furnace with the characteristic of the complicated nonlinear, strong coupling,time-varying and time-lag, the traditional PID control strategy or modern classical controltheory are hard to reach the expected high precision control effect, so it need to use compoundintelligent control technology to improve the electrode regulator in order to optimize thesystem control effect.On the basis of Intelligence Control theory, the paper is mainly to make a deep analysisand research to the EAF electrode regulator system, combined with the steelmaking’sdevelopment process. It was put forward an intelligent control method based on thecombination of neural network, fuzzy control and PLC computer control system. The mainstudy work has the following three aspects:(1) In accordance with control method requirements of the EAF electrode regulatorsystem, combining with the relevant theoretical knowledge and working principles analysis ofEAF, the mathematical simulation model of AC EAF has been built, finally the conclusion isverified by the followed simulation results.(2) Aim at the smelting process characteristics of the modern EAF, the whole cycle of theEAF smelting is divided to two stages, they are melting stage and oxidation-reduction stage,the paper control the electrode by using sub-section strategy. During the melting stageelectrode regulating controller is supposed to have fast dynamic response without overshootdue to impact of obvious external disturbance and arc length variations. So an intelligentcontrol method based on genetic algorithms, neural networks and PID was adopt to realize thequick adjustment, and the simulation results show that the controller is a good fast transientresponse. Within the oxidation-reduction stage electrode regulating controller is required toachieve both the efficiency and precision two performance index owing to relative less disturbance and stable arc length, so an intelligent control method based on fuzzy and PIDcontrol was come up, the simulation indicates the control method can obtain expected controleffect.(3) By establishing computer control system of the EAF electrode regulator based onSiemens S7-400PLC, modeling, simulation and software process of the electrode regulatorsystem could be combined in order to realize the automatic control of smelting process.