摘 要
摘 要
在钢铁工业生产过程控制中，通常会遇到的是加热炉炉温动态特性控制，它具有如下特征：（1）炉温上升和下降往往具有严重的不对称性，包括增益和滞后时间的不对称性。（2）容积滞后。对于一般工业加热炉炉温控制特性具有较大的容积滞后，而且属于纯滞后特征。（3）在加热炉的整个温度调节范围内，对象的增益、容积滞后时间通常是与工作温度与负载变化有关的变参数。对于加热炉这类工业对象，采用常规的PID控制器，在工作点附近的小范围内，由于其动特性近似于线性，有可能控制得较好；但当大范围改变给定值或受外界环境（包括工况）太大扰动时，就需要及时修正PID参数，否则将使温升动特性变差。随着现代工业技术的发展，对工业炉温控制性能要求也必然越来越商，要求有更先进的控制策略来满足这些要求。由于温度控制在加热炉设备自动化控制中是一个非常重要的方面，但加热炉是一个非线性的、时变的、分布参数多的复杂被控对象，具有滞后的特性，因而加热炉的炉温是一个较难控制的参数。基于此，本研究将利用西门子S7-300PLC控制加热炉温度控制系统。
本文介绍了步进式加热炉的结构、工艺和控制要求，归纳了步进式炉的控制现状，分析了步进式加热炉炉温控制系统，并针对存在的问题进行以下几个方面的研究：
第一，针对步进式加热炉炉温控制过程中存在的滞后的特点，提出PLC过程控制的相关理论。
第二，通过对加热炉的温度控制进行传统 PID 过程控制进行仿真比较，提出加热炉炉温控制系统的方案设计。
第三，系统的学习了 SIMATIC S7-300PLC控制系统，学习PLC 中先进过程控制库中的功能模块和使用方法，有了深层次的消化吸收，并学习了在PLC系统中如何创建工程项目的方法步骤，在对PLC系统下加热炉炉温控制的硬件和软件进行设计与研究。
结果表明，对基于PLC的加热炉进行控制使炉温能够快速跟随给定并达到稳定状态，这对日后研究加热炉炉温优化工作打下了坚实的基础。通过本文的研究对加热炉炉温的智能化控制提供一定的参与借鉴。
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关键词：PLC；加热炉；炉温；控制
ABSTRACT ABSTRACT
The characteristics of a heating furnace temperature control, it has the following characteristics: (1) the temperature rising and falling tend to have a serious asymmetry, including the asymmetry of the gain and the time lag. (2) Volume lags. For general industrial furnace temperature control features with larger volume, and belongs to pure hysteretic characteristics. (3) in the whole heating furnace temperature control range, the object's gain, volume lag time is usually variable parameters associated with the working temperature and load changes. For this type of industrial heating furnace object, using the conventional PID controller, near the working point of small scale, due to its dynamic characteristics similar to linear, can control it better; But when the big scope change given value or the external environment disturbance (including condition) is too big, will need to be revised PID parameters in time, otherwise will make dynamic characteristic of temperature variation. With the development of modern industrial technology, the industrial furnace temperature control performance requirements also more and more, necessarily requires a more advanced control strategies to meet these requirements. Due to the temperature control in the heating furnace equipment automation control is a very important aspect, but the heating furnace is a nonlinear, time-varying and distributed parameter more complex controlled object, has characteristic of lag, as a result the temperature of heating furnace is a more difficult to control the parameters. Based on this, this study will use the Siemens S7-300 PLC control furnace temperature prediction control system.
Step by step heating furnace are introduced in this structure, process and control requirements, step furnace control present situation, summarizes the step furnace temperature prediction control system are analyzed, and the study of existing problems in the following aspects:
First, in view of the step in the process of the furnace temperature control is the characteristics of the lag of relevant theory of PLC process control are put forward.
Second, through to the heating furnace temperature control process of traditional
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PID control and control are compared, and the simulation scheme design of reheating furnace control system is put forward.
Third, the system of learning the SIMATIC S7-300 PLC control system, learning advanced PLC in process control in the library function module and method of use, with deep digestion and absorption, and learning in a PLC system how to create the steps of the project, under the system of PLC furnace temperature prediction control hardware and software to carry on the design and research.
Results show that the forecast of the heating furnace based on PLC to control the furnace temperature can quickly follow given and reach the stable state, the reheating furnace optimization in the future research work has laid a solid foundation. Through the study of this article is for the participation of reheating furnace of intelligent control to provide certain reference.
Key words: PLC; The heating furnace; Furnace temperature; control
目 录
目 录
摘 要 .................................................................I ABSTRACT ...............................................................I 第1章 绪论 ............................................................1
1.1 课题背景及意义 ..................................................1 1.2 PLC过程控制系统 ................................................1
1.2.1 PID过程控制概述 ...........................................1 1.2.2 PLC过程控制的特点 .........................................2 1.3 研究内容及思路 ..................................................4 第2 章 步进式加热炉工艺和炉温控制原理 ..................................5
2.1 步进式加热炉工艺 ................................................5
2.1.1 步进式加热炉内坯料的运动 ..................................5 2.1.2 步进式加热炉的炉底结构 ....................................6 2.2 加热炉炉温控制原理 ..............................................7 2.3 本章小结 ........................................................8 第3章 加热炉炉温控制系统的方案设计 ....................................9
3.1 加热炉炉温控制系统的基本构成 ....................................9 3.2 加热炉燃烧系统工艺流程 ..........................................9
3.2.2 压力检测与控制 ...........................................13 3.2.3 流量检测与控制 ...........................................14
第4章 加热炉炉温 PLC软硬件设计 .......................................15
4.1 控制部分的硬件组态 .............................................15
4.1.1 主站组态 .................................................15 4.1.2 从站组态 .................................................18 4.2 S7-300 PLC的编程方法 ..........................................23
4.2.1 Step7编程软件包构成与编程方式 ...........................23 4.2.2 编程过程分析 .............................................24 4.3 炉温控制系统软件设计 ...........................................25
4.3.1 加热炉控制系统整体软件介绍 ...............................25 4.3.2 加热炉炉温自动调节程序设计 ...............................26 4.3.3 组织块OB150 ..............................................31 4.4 数字滤波程序 ...................................................31 4.5 FUZZY控制流程 .................................................31 4.6 本章小结 .......................................................34 第5章 PLC加热炉炉温控制系统应用 ......................................35
5.2 WinCC工作流程 ................................................35 5.3 加热炉流程及温度控制画面 .......................................35 5.4 变量记录 .......................................................37 第6章 总结与展望 .....................................................38
6.1 结论 ...........................................................38
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