基于PLC变频恒压供水控制系统设计

摘 要

本论文根据中国城市小区的供水要求，设计了一套基于PLC的变频调速恒压供水系统。变频恒压供水系统由可编程控制器、变频器、水泵机组、压力传感器等构成。

本系统包含四台水泵电机，它们组成变频循环运行方式。采用变频器实现对四相水泵电机的软启动和变频调速。压力传感器检测当前水压信号，送入PLC与设定值比较后进行PID运算，从而控制变频器的输出电压和频率，进而改变水泵电机的转速来改变供水量，最终保持管网压力稳定在设定值附近。通过工控机与PLC的连接，采用组态软件完成系统监控，实现了运行状态动态显示及数据、报警的查询。 关键词：变频调速 恒压供水 PLC

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ABSTRACT

According to the requirement of China's urban water supply, this paper designs a set of water supply system of frequecey control of constant voltage based on PLC, and have developed good operation management interface using Supervision Control and Data Acquisition.The system is made up of PLC, transducer,units of pumps,pressure sensor and control machine and so on.

This system is formed by three pump generators,and they form the circulating run mode of frequency conversion. With general frequency converter realize for three phase pump generator soft start with frequency control,operation switch adopts the principle of”start first stop first”. The detection signal of pressure sensor of hydraulic pressure,via PLC with set value by carry out PID comparison operation,so,control frequency and the export voltage of frequency converter,and then the rotational speed that changes pump generator come to change water supply quantity,eventually,it is nearby to maintain pipe net pressure to stabilize when set value. Through work control machine the connection with PLC,with group form software consummately systematic monitoring,have realized operation state development to show and data,report to the police inquiry.

Keywords: Variable frequency speed-regulating Constant-pressure water supply PLC

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目录

第一章 绪论.........................................................1

1.1课题的提出...................................................1 1.2变频恒压供水系统的国内外研究现状.............................2 1.3本课题的主要研究内容.........................................3 第二章 系统的理论分析及控制方案确定.................................4

2.1变频恒压供水系统的理论分析...................................4

2.1.1 电动机的调速原理.......................................4 2.1.2 变频恒压供水系统的节能原理.............................4 2.2变频恒压供水系统的理论分析...................................5

2.2.1 控制方案的比较和确定...................................5 2.2.2 变频概述...............................................6 2.2.3 变频恒压供水系统的组成和原理图.........................7 2.2.4 变频恒压供水系统控制流程...............................9 2.2.5 水泵切换条件...........................................9

第三章 系统的硬件设计..............................................11

3.1系统主要设备的选型..........................................11

3.1.1 控制方案的比较和确定..................................11 3.1.2 欧姆龙CP1E PLC简介..................................13 3.1.3 PLC 及其模块的选型....................................14 3.1.4 变频器的选型..........................................14 3.1.5 水泵机组的选型........................................15 3.1.6 压力变送器的选型......................................15 3.1.7 液位变送器的选型......................................16 3.2系统主电路分析及其设计......................................16 3.3系统控制电路分析及其设计....................................17 3.4 PLC的I/O端口分配及外围接线图..............................19 第四章 系统的软件设计..............................................22

4.1系统软件设计分析............................................22 4.2 PLC程序设计................................................23

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4.2.1 控制系统主程序程序设计................................23 4.2.2 控制系统子程序设计....................................26 4.3 PID控制器参数整定..........................................35

4.3.1 PID 控制及其控制算法..................................35 4.3.2 PID 参数整定..........................................36

第五章 结束语......................................................38 参考文献...........................................................39 致谢...............................................................40 附录...............................................................41 附录图1主电路图................................................41 附录图2控制电路图..............................................42 附录图3主程序流程图............................................43 附录图4主程序梯形图............................................44

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