C3000实现的非线性PID在pH定值控制中的应用

Application of Nonlinear-PID in pH Value Control Based on C3000

在化工生产应用中，对pH值进行精确控制具有一定困难，尤其是要求将反应溶液的pH值控制在7～8之间，一直是工业控制中没有很好解决的难题之一。根据pH值控制本身非线性的特点。提出了三区段后补偿非线性PID控制算法，将线性的PID输出通过指数函数非线性化，并利用㈣方便的组态和强大的运算控制功能将其实现。某乙烯厂急冷水和稀释蒸汽发生系统中的应用实例表明，使用㈣实现的三区段后补偿非线性PID控制算法适应性强、响应速度快、控制精度高，在设定pH值变化的定值控制中具有很好的应用。

It is hard to control the pH neutralization reaction, in one value exactly, Especially making the pH value controlled between 7 - 8, is the problem that has no good solution in industry control now. According to this inherent characteristics in pH neutralization reaction, a three-segment PID algorithm with nonlinear step-compensation is presented, which makes the output of PID nonlinear. With the strongly available function of C3000, the algorithm is realized conveniently. The application in one factory performed with this algorithm show that the proposed algorithm possesses such advantages as good robustness, quick response, and high control accuracy. It performs perfectly in the pH value control with alterant set-value.