定值控制系统中正反作用的简易判定方法

A Simple Method for Determining the Positive and Negative Effects in a Constant Value Control System

具有负反馈的定值控制是化工生产中比较常用的控制系统,目的在于保证生产中各个工段的生产参数处于相对稳定的状态,即在给定值的基础上只允许存在微小波动;环节包含测量元件及变送器、控制器、执行器(控制阀)和被控对象,如果它们组合不当,轻则降低控制品质,重则使总的作用方向构成正反馈形式,控制系统不但不能起到控制作用,降低外部干扰因素的扰动,反而破坏了生产的稳定。文章结合多年教学经验,归纳了各个环节正反作用的判定方法,使学生更易理解和掌握。

Constant value control with negative feedback is a common control system in chemical production,which aims at ensuring that the production parameters of each section in production are in a relatively stable state,that is,only a small fluctuation is allowed on the basis of the given value.The link includes the measuring element and transmitter,controller,actuator(control valve)and controlled object,if they are not combined properly,the control quality will be reduced,and the general direction of action will form a positive feedback form.The control system will not only fail to play a role of control,but also reduce the disturbance of external interference factors,which will destroy the stability of production.Combining with the teaching experience for many years,this paper sums up the judging methods of the positive and negative effects of each link,so as to make it easier for students to understand and master.