【作者】 李刚；

【导师】 郑艳；

【作者基本信息】 东北大学 ， 控制工程， 2008， 硕士

【摘要】 结晶器液位自动控制已经成功应用在铸坯截面为150 mm×150 mm以上的板坯连铸机上,而在小方坯连铸机(铸坯截面为130mm×130 mm)上的应用效果不佳。虽然首钢是国内领先的连铸大企业,但小方坯铸机还都是手动开浇,人工控制结晶器液面高度,自动控制技术远远落后于发达国家,钢坯质量很难得到改善。为了进一步提高小方坯的质量,同时也为了积累连铸机自动化改造经验,在消化吸收国内外其他钢铁厂连铸机结晶器液位控制理念的基础上,设计了适用于小方坯连铸机的结晶器液位自动控制系统。本文首先根据液位控制的机理建立了各个环节的数学模型。并分析了模糊控制方法和PID控制方法各自的特点,将模糊控制和PID控制有机结合起来,设计了Fuzzy-PID复合控制器。该控制器综合了模糊和PID两种控制方式的优点,既具有模糊控制对非线性系统控制的有效性,又具有PID控制的精确性。在系统建模和控制器设计的基础上,采用Matlab仿真软件对PID控制和Fuzzy-PID复合控制两种控制算法进行仿真研究,仿真结果表明Fuzzy-PID复合控制较常规PID控制具有更好的稳定性和控制精度,该系统具有结构简单、抗干扰能力强,调整时间短等优点,可同时兼顾控制系统的动静态性能。在理论研究的基础上,采用西门子S7-300系列PLC、STEP7编程软件和WinCC4.0组态软件,对控制系统的上、下位机的软、硬件进行了设计、编程及调试,实现了结晶器液位的Fuzzy-PID复合控制。液位检测使用放射性同位素(CS137)检测法；在塞棒执行机构上使用了高精度数字电动缸,将液位串级控制结构简化为一阶闭环控制,缩短了系统响应时间,将结晶器液位误差控制在±5mm之间,基本达到要求。应用表明,Fuzzy-PID复合控制器具有良好的动态、静态特性和一定的鲁棒性,而且控制算法简单,实现方便,有效地提高了铸坯质量。更多还原

【Abstract】 Mold level control has been successfully used in the slab continuous casting machine that cross sectional area is above 150 mm×150 mm, but effect is not good for the billet caster (the cross sectional area is 130 mm×130 mm.). Although Shougang is a large enterprises in output aspect of the continuous casting in domestic production, but automatic control technology of Shougang lagges far behind the developed countries. It is difficult to improve the product quality with artificial casting and liquid level control. On the basis of the digestion and absorption of ideas of continuous caster mold level control of other steel plants it had designed a mold level control system in suitable for billet caster, for further improving of the quality of billet and for builting on experiences of automation of others continuous casters.At first in this paper, it had established mathematical model of each constituent part according to the mechanism of mold level control system. Then it had analyzed the characteristics of the fuzzy and PID control and then combined them organically. A Fuzzy and PID Hybrid controller is designed in this paper. This controller synthesizes the advantages of both fuzzy and PID controlling modes, thus making the controller possess not only the simplicity and efficiency of the fuzzy in controlling over the non-linear system but also the accuracy of PID controlling. Based upon the system modeling and the design of controller it had carried on the simulation experiment for PID and Fuzzy-PID Hybrid algorithm by using the Matlab software. The simulation results show that this system has a better stability and a higher precision than conventional PID system. This method has the advantages of simple structure, stronger anti-jamming ability and quick response, and according to both dynamic and static characteristics of system.Based on theoretical research, in this control system it had used the Siemens S7-300 PLC, programmed and debugged software with STEP7 and WinCC 4.0 configuration software for software and hardware of host computer and lower computer. Compound fuzzy-PID control of mold level was realized. The method of detection of level is method of radio isotopic detection (Cs137); the implementing agencies for stopper on the use of high-precision digital electric cylinder, which simplifies the mold level control structure from cascade control structure to one order closed-loop control and shortens to the response time of the implementing agencies. In the production process, error of the mold level in±5mm, which meets the requirements basically. Application shows that the controller has good dynamic and static characteristics and a certain robustness. Control is simple and easy to achieve. In this way, product quality is improved effectively.更多还原