摘 要
水箱和换热器是过程控制中的典型对象，本设计主要以水箱液位控制系统和换热器温度控制系统为例，通过建立数学模型，确定对象的传递函数。利用Matlab的Simulink软件包对系统进行了仿真研究，并对仿真结果进行了深入的分析。
在水箱液位控制系统中，通过建立数学模型以及实验中对实验数据的分析，分别确定了单容、双容、三容水箱对象的传递函数。在simulink软件包中建立了各系统的仿真模型。通过对仿真曲线的研究，分析了控制器参数对系统过渡过程的影响。
在换热器温度控制系统中，根据自动控制系统工艺过程，利用降阶法确定了对象的传递函数。在软件包Simulink中搭建了单回路、串级、前馈—反馈控制系统模型，分别采用常规的PID、实际PID和Smith预估器对系统进行了仿真研究，通过仿真曲线的比较，分析了各种控制系统的特点。
关键词：过程控制；MATLAB；仿真；水箱；换热器
Simulation and Research of Process Contro1
System Based on MATLAB
Abstract
Water tank and Heat exchanger are typical object in the process control in the design,The control system of tank level and heat interchange is used as an example.The transfer function object is defined by setting up the mathematical model.I carry on simulation research on the system by using Matlab’s simulink simulation.and deeply analyze the result of the simulation.
In the system, which control the level of the tank. The transfer function of a single-tank, double-tank, three-tank is defined by setting up mathematical model and analyzing date. Simulation model of all system set up simulink simulation. The effect that controller parameter composes on the system is analyzed through the research on the simulation cuvers.
In the control system of heat inter change. The design uses reduction method and defines the transfer function of the object.according to the technical process in the automatic system.The control system model of single loop, cascade, feed forward-feedback is established. Simulation research on there system is carried on through using conventional PID, the actual PID and Smith predictor , While the characteristics those control system are compared.
Key words: Process Control; Matlab; Simulation; Water tanks; Heat exchanger
目 录
摘 要 ......................................................................................................................................... I Abstract ......................................................................................................................................II 第一章 引 言 ............................................................................................................................ 1
1.1 过程控制简介 ............................................................................................................. 1 1.2 过程控制的发展 ......................................................................................................... 1 1.3 控制系统仿真的含义 ................................................................................................. 2 1.4 矩阵实验室Matlab简介 ............................................................................................ 2 1.5 动态系统软件包Simulink简介 ................................................................................. 3 1.6 控制系统仿真的一般步骤 ......................................................................................... 4 第二章 过程控制系统概述 ...................................................................................................... 5
2.1 过程控制中常见的控制系统 ..................................................................................... 5
2.1.1 单回路控制系统 .............................................................................................. 5 2.1.2 串级控制系统 .................................................................................................. 5 2.1.3 前馈控制系统 .................................................................................................. 6 2.1.4 前馈—反馈控制系统 ...................................................................................... 7 2.2 通道特性对控制质量的影响 ..................................................................................... 8
2.2.1 干扰通道特性对控制质量的影响 .................................................................. 8 2.2.2 控制通道特性对控制质量的影响 .................................................................. 8 2.3 控制器参数对系统的影响 ....................................................................................... 10 2.4 控制器控制规律的选择 ........................................................................................... 10 2.5 控制器参数整定 ....................................................................................................... 11 第三章 液位控制系统的仿真研究 ........................................................................................ 12
3.1 单容水箱液位控制系统 ........................................................................................... 12
3.1.1 单容水箱数学模型 ........................................................................................ 12 3.1.2 控制方案 ........................................................................................................ 14 3.1.3 单容水箱的Simulink仿真 ............................................................................ 14 3.2 双容水箱液位控制系统 ........................................................................................... 17
3.2.1 双容水箱数学模型 ........................................................................................ 17 3.2.2 控制方案 ........................................................................................................ 19 3.2.3 双容水箱的Simulink仿真 ............................................................................ 19 3.3 三容水箱液位控制系统 ........................................................................................... 23
3.3.1 三容水箱的系统建模 .................................................................................... 23 3.3.2 三容水箱的Simulink仿真 ............................................................................ 24 3.4 本章小结 ................................................................................................................... 25 第四章 换热器温度控制系统仿真研究 ................................................................................ 27
4.1 换热器的数学模型 ................................................................................................... 27
4.1.1 换热器构造及工作原理 ................................................................................ 27 4.1.2 被控参量的选择 ............................................................................................ 28 4.1.3 被控对象的特性 ............................................................................................ 29 4.1.4 被控对象数学模型的建立 ............................................................................ 29 4.2 单回路控制系统 ....................................................................................................... 33
4.2.1 常规PID控制 ................................................................................................ 34 4.2.2 实际PID控制系统仿真 ................................................................................ 36 4.2.3 史密斯(Smith)预估控制系统仿真 ................................................................ 39 4.3 串级控制系统 ........................................................................................................... 41