Development And Application Of Digital Smart-current Regulation System Based On Plc

Electrolytic aluminum smelter is one of the high energy consuming industries under the control of national industrial policy. Thus how to reduce the power consumption is an important subject concerning the survival of the industry. With the development of technology, there are various methods to reduce the power consumption, such as adopting advanced types of pots, reducing the pot temperature and increasing the stability of the direct current etc... Among them, to increase the stability of the current by using advanced current regulation technology is one of the measures that cost less but effect faster. And many enterprises are working on it.With the background of the development of the digital auto-current regulation technology, this paper aims at the actual production requirements for the smelter enterprises, presents the digital auto-current regulation technology, elaborates the control principle and ways of implementation for the PLC digital auto-current regulation system; and analyzes the difficulties in systematic control, control methods and optimization of the control calculation method; establishes a general technical scheme based on PID adjustment for a double closed-loop control system which is composed of a big closed-loop of series total current and a small closed-loop of single unit current.With the fast development of the web technology, electrical and electronic technology as well as the PLC auto-control technology, the control technology for the rectification system in the power supply station of the smelter is also developing quickly and in the direction of intelligent, web control and modularization. The key part of the current regulation control lies in the control for the transductor. PWM DC chopper control technology is adopted to control the transductor current in this system, adjusting the space ratio of the power element IGBT in order to change the control current of the transductor. This control system is a complete digital intelligent current regulation system, i.e. each control link, such as the control of the current regulation system, adjustment, ignition, signal process etc. are all controlled by PLC or other intelligent control devices through software programme. There is no need to adjust them through hardware in the control system. The information exchange in the current regulation system includes preset control, shift of the current regulation control mode and state monitoring of the current regulation system. It realizes the intelligent web control. This system has been put into operation successfully in CHALCO, Guizhou Branch. It is an advanced technology in china.