变频泵加工频泵的恒压供水系统
摘要
介绍了用S7-200进行逻辑及PID控制，用PLC进行压力调节，自动控制小水泵投入的台数和大水泵电机转速，在保持恒压状况下，达到节约电能的目的。基于PLC和变频器技术的恒压供水系统的组成和工作原理，给出了控制系统的硬件组成和软件设计方案。运行结果表明，该系统具有压力稳定，结构简单，工作可靠等特点。
设计了利用PLC和变频器实现自动恒压供水的控制系统。采用PLC内置的PID调节器，选用一台变频器和一台PLC分别控制两台大泵机和五台小泵机进行恒压供水。
采用西门子PLC及变频器为主控单元，配合接触器、继电器实现恒压变频供水系统的PID控制——实时跟踪管网压力与给定压力的偏差变化，经PLC内部PID运算，通过可编程控制器控制变频与工频切换，自动控制水泵投入的台数和电机转速，实现闭环自动调节恒压变量供水的目的。系统性能稳定，投资小。
关键词：PI调节器；PLC；变频器；恒压供水；压力
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Abstract
This dissertation introduces a constant pressure water supply system, which used S7-200 to process logic control，PID control and employed inverter to adjust water pressure. It could automatically control the number of water pump and speed of A.C motor, save electric energy. The structure and working principle of a constant pressure water supply system based on PLC and frequency variation technique, the hardware and the software of the control system are introduced in detail. The system in practice proves to have constant water pressure, simple structure and better reliability. Designed a water supplying system with automotive constant pressure based on PID and PLC technology. The system used the PID, which was inside PLC, PLC and frequency inverter to control five small water pump and two big water pump. It adopts Siemens’ PLC and frequency converter as top management unit, cooperates with contactor and relay in order to realize the PID control water-supply system of constant pressure--- They follow up the deviation between the pipe network pressure and pressure given. Through operation of PID and switchover of frequency conversion and power frequency was controlled by PLC, it could automatically control number of water pump put into operation and speed of AC motor for veining automatic regulation of close-loop and supplying water under constant pressure and variety runoff.
Key words ：Proportional integral； programmable logic control；frequency inverter；constant pressure water supply system；pressure
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目录
摘要................................................................................................................................ I Abstract ......................................................................................................................... II 第一章 引言.................................................................................................................. 1
1.1变频泵加工频泵的恒压供水系统设计背景................................................... 1 1.2工作原理........................................................................................................... 2 1.3变频泵加工频泵的恒压供水系统设计目标及要求....................................... 3
1.3.1泵站技术指标简介................................................................................. 3 1.3.2本设计预期达到目标............................................................................. 4 1.4技术综述........................................................................................................... 4
1.4.1恒速泵供水............................................................................................. 5 1.4.2高位水箱供水......................................................................................... 5 1.4.3气压罐供水............................................................................................. 6 1.4.4水箱管网联合型..................................................................................... 6 1.4.5变频恒压供水......................................................................................... 6 1.5本章小结........................................................................................................... 6 第二章 控制系统算法简介.......................................................................................... 8
2.1控制原理与PID数学模型 .............................................................................. 8
2.1.1控制原理介绍......................................................................................... 8 2.1.2 PID介绍 ................................................................................................. 9 2.2系统的组成..................................................................................................... 14 2.3本章小结......................................................................................................... 17 第三章 硬件设计........................................................................................................ 19
3.1变频器选用..................................................................................................... 20 3.2 PLC介绍 ........................................................................................................ 21
3.2.1PLC简介 ............................................................................................... 21 3.2.2 PLC的基本结构 .................................................................................. 21 3.2.3 PLC的特点 .......................................................................................... 23
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3.2.4 PLC的功能 .......................................................................................... 25 3.3 PLC的选型 .................................................................................................... 27
3.3.1概述....................................................................................................... 27 3.3.2 CPU226工作特点的概述 .................................................................... 28 3.3.3扩展单元介绍....................................................................................... 29 3.4 PLC控制系统的设计 .................................................................................... 31 3.5电气控制线路的绘制..................................................................................... 38
3.5.1电器原理图........................................................................................... 38 3.5.2主电路图的设计................................................................................... 39
3.6 本章小结............................................................................................................... 40 第四章 软件设计........................................................................................................ 41
4.1 SIMATIC S7-200系列PLC编程软件介绍 .................................................. 41
4.1.1 系统软件.............................................................................................. 41 4.1.2 用户程序.............................................................................................. 42 4.1.3软件界面简介....................................................................................... 44 4.2 PLC存储器分配表 ........................................................................................ 45 4.3泵站软件的设计分类..................................................................................... 46
4.3.1软件设计综述....................................................................................... 46 4.4 本章小结........................................................................................................ 48 结束语.......................................................................................................................... 49 参考文献...................................................................................................................... 50 附录.............................................................................................................................. 50 致谢.............................................................................................. 错误！未定义书签。
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