毕业设计（论文）
题 目： 蒸汽/热水型换热器数字PID控制系统 的设计与仿真
学 院： 信息工程学院 专业名称： 电子信息科学与技术 班级学号： 12043109 学生姓名： 武勇 指导教师： 江晶
二O一六 年 6 月
蒸汽/热水型换热器数字PID控制系统的设计与仿真
学生姓名：武勇 班级：120431 指导老师：江晶
摘要：在当今社会的工业领域之中，换热器已经逐渐成为一种标准的工艺设备，
并且已经广泛的应用于动力工程领域和一些其他的过程工业部门。本次实验是要求以控制输入蒸汽流量来达到输出热水温度的稳定。但是，由于被控对象为蒸汽流量，故存在大惯性、参数时变、纯滞后等非线性特点，所以利用传统的PID控制不能满足其动态、静态特性的要求。单一的控制方式和现在制造工艺的限制，导致目前换热器普遍存在效果差，效率低的现象同时也造成了能源的浪费。如何改变这样的现状，提高换热器的控制效果及效率，对于缓解能源紧张的状况具有长远的意义。本课题是通过PID控制系统来调节换热器的输入（蒸汽流量），来控制输出（热水温度），同时也引入了smith预估器来解决时滞问题，通过建立数学模型来求取被控对象的传递函数，从而建立simulink模型，通过MATLAB仿真得到其阶跃响应曲线图。
本文首先基于开环阶跃响应曲线法，通过调节参数（蒸汽流量）的阶跃输入作用下得到被控参数（供水温度）的变化规律，从而得到广义被控对象的特性参数，从而得到换热器的开环传递函数，通过搭建模型仿真观察结果，未达标，引入smith预估器重新搭建模型仿真并与之前的图形对比，接着采用PID进行校正，基于时域响应法进行PID参数整定，最后，修改比例、积分、微分三个环节的参数并对比确定最后的取值，并观察结果符合要求。
关键词：换热器 时滞 PID控制 smith预估器
指导老师签名：
Design and Simulation of digital PID control system for steam /
water heat exchanger
Student name : wu yong Class: 120431 Supervisor: jiang jing
Abstract: In the industrial field of today's society,Heat exchanger has gradually
become a standard process equipment,And has been widely used in the field of power engineering and some other process industries. This experiment is required to control the input steam flow rate to achieve the output hot water temperature stability. But, Due to the controlled object as the steam flow, there are some nonlinear characteristics such as large inertia, time varying parameters and time delay.So the use of traditional PID control can not meet the requirements of its dynamic and static characteristics.Single control mode and current manufacturing process limitations,At the same time, the current heat exchanger has poor efficiency and low efficiency, and it also causes the waste of energy.How to change the current situation, improve the control effect and efficiency of the heat exchanger, to ease the situation of energy tension has a long-term significance.This topic is through the PID control system to regulate the heat exchanger input (steam flow), to control the output (hot water temperature),At the same time, the Smith predictor is introduced to solve the problem of time delay,By establishing mathematical model, the transfer function of the controlled object is obtained,So as to establish the Simulink model, the step response curve of the MATLAB model is obtained by the simulation.
In this paper, based on the open loop step response curve method,The variation law of controlled parameters (water temperature) was obtained by adjusting the step input of the parameters (steam flow),The characteristic parameters of the generalized controlled object are obtained,The open loop transfer function of the heat exchanger is obtained,By setting up the model simulation results, not up to the standard,The Smith predictor is introduced to build the model simulation and compare with the previous figure,Then use PID to correct,PID parameter tuning based on time domain response method,last，Modify the proportion, integral, differential parameters of the three links and determine the final value, and observe the results meet the requirements.
Keyword：Heat exchanger time lag PID control smith predictor
Signature of Supervisor:
目 录
1 绪论
1.1 PID控制的目的和意义 ·················································· (5) 1.2 PID控制的国内外发展状况 ············································ (5) 1.3 换热器PID控制系统的设计方法 ····································· (7) 1.4 本文的主要研究内容 ···················································· (7)
2 换热器PID控制系统的构建
2.1 换热器的简要介绍 ······················································· (9) 2.2 控制方案的设计 ·························································· (9) 2.3 传递函数的求取 ·························································· (9) 2.4 PID的简要介绍 ·························································· (9) 2.5 Smith预估器 ······························································ (11)
3 基于MATLAB的simulink模型建立
3.1 仿真系统模型的建立 ···················································· (13) 3.2 控制系统的时域分析 ···················································· (13) 3.3 阶跃信号输入的优点 ···················································· (13) 3.4 simulink模型建立 ······················································ (14)
4 参数校正及仿真
4.1 PID参数的整定 ·························································· (18) 4.2 校正系数的确定 ·························································· (18) 4.3 仿真结果及分析 ·························································· (18)
5 结论
结 论 ······································································ (25) 参考文献 ······································································ (26) 致 谢 ······································································ (27)
1 绪论
1.1 蒸汽/热水型换热器数字PID控制的目的和意义
本次研究的是蒸汽/热水型换热器数字PID控制系统的设计与仿真。现在，随着社会的发展，文明的发展，人们已经把节约能源看作是一种十分重要的事情。节约能源是指尽最大可能的去降低能源的耗损、增大对能源的使用率等等的这一系列行为。增强对能源使用的管治，采用在经济方面、技术方面合理，同时在社会和环境都可以承受的范围之内的措施，从能源的出产开始到消耗等其中的多个环节，来减低能源的耗损、降低能源的损失和污染物产生、制止一些浪费行为，有效、且合理的去利用能源。现如今，在我国，石油、化等工产业中，换热器普遍都受到了重视，而换热器的广泛采用，也决定了换热器换热性能的改善，以及设计理论的不断创新，企业的经济收益和工业的飞速发展都具有一定的积极作用，为节约能源和保护环境做出了显著的贡献。
在实际的工程之中人们使用最多的控制规律为，比例（proportional)、积分(integral)、微分(derivative)控制，也就是PID控制，又称之为PID调节。PID控制，实际中也分有PI控制和PD控制。PID控制器的原理就是：通过系统产生的误差，采用比例、积分、微分来求出控制量从而进行控制的。稳定性是系统控制品质好坏的一个重要的指标。因此对PID控制的稳定性研究工作在工控领域中有着非常重要的意义。
PID控制器问世至今已经有将近70年的历史了，它的算法相对简单、鲁棒性好、可靠性高，在过程控制和运动控制之中应用广泛。各种各样的PID控制器已经在工程实际中得到了非常广泛的应用，例如使用PID控制完成的温度、流量、压力、液位控制器等，可编程的控制器也有采用PID控制的，甚至还有实现PID控制的PC系统等等。PID控制适合于那些数学模型无法精确建立的控制系统。伴随着现代工业的发展，被控对象的复杂程度也在不停的增大，特别是对于那些存在滞后、时变的、非线性的繁杂的控制系统，当中有的参数不可得知或者是变换较为迟缓，有的带有延迟或者是随机干扰，有的不能获得较为精准的数学模型或者是模型比较粗糙，加之现在我们对予控制品质的要求也在日益增长，这就用到了PID控制。
1.2 PID控制的国内外发展状况
在之前的五十年时间里，调整PID控制器里参数值的研究取得了极好的发展。其中有利用环阶跃响应信息。例如 Coon-Cohen 响应曲线法，还有的使用Nyquist 曲
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