模拟冷却塔计算机控制系统的设计与实现

Design and Implementation of Analog Cooling Tower Computer Control System

为了在实验室内精确的模拟各种冷却试验,研制了采用抽风式机械通风结构的逆流式模拟冷却塔,介绍了该塔的整体结构和工作原理;以流量或温度作为被控对象,可以近似看作一阶惯性滞后模型,在获得对象的飞升曲线后,用Cohn-Coon公式求对象参数,在最小模型假设的前提下,由Ziegler-Nichols整定法结合人工整定得到PID参数;测试实验中水温和风温稳定后都可控制在设定值的±0.1℃,实验结果表明,该冷却塔设计合理,控制精度高,能够满足各种冷却试验使用要求。

In order to simulate a variety of cooling experiments accurately in the laboratory, a reverse flow type analog cooling tower, adopting exhaust fan as its mechanical ventilation structure, is developed. The integral structure and working principle of the tower are in troduced. The system can be approximately considered as a first-order model with dead time. The parameters of the model are determined by the Cohn-Coon formula after obtaining the step response curve of the controlled objects. Under the precondition of minimal model, PID parameters are acquired by using Ziegler- Nichols tuning method and artificial tuning. After the water temperature and wind temperature are stable in the experimental field, they can be controlled in the set value ±0. 1℃. The experiments show that the cooling tower is reasonably designed, having high control precision and can satisfy all kinds of cooling experiment needs.