摘要随着社会经济的迅速发展,人们对供水质量和供水系统可靠性的要求不断提高;再加上目前能源紧缺,利用先进的自动化技术、控制技术以及通讯技术,设计高性能、高节能、能适应不同领域的恒压供水系统成为必然趋势。本课题用PLC实现了自动供水控制系统,介绍了恒压供水的基本原理以及系统构成的基础,说明了可编程控制器(PLC)在恒压供水系统中所担任的角色。从系统的整体设计方案和实际需求分析开始,紧密的联系实际生活的需要,力求做到使系统运行稳定,操作简便,解决实际中问题,保证供水安全、快捷、可靠。关键字:PLC恒压供水变频器ABSTRACTWiththerapiddevelopmentofsocialeconomy,itisdemandedthebetterofwatersupply’squalityandreliabilityofwatersupplysystem.Meanwhileenergyresourcesareseriouslylack.Soitisinevitabletendencytodesignwatersupplysystemwhichhashighfunctionandsavesonenergywell,withhelpofadvancedtechniqueofautomation,controlandcommunication.Atthesametimethissystemcanadaptdifferentwatersupplyfields.ThissubjectrealizetheautomaticwatercontrolsystemthatusedofPLC,itintroducedthebasicprinciplethatconstantvoltagesupplieswaterandfoundationthatthesystemform,havestatedtheroleservedasoftheprogrammablecontroller(PLC)inthewater-supplysystemofconstantvoltage.Sincethewholedesignplanofthesystemandactualdemandareanalysed,theneedofcloselifeofintergratingwithpractice,makeeveryefforttomakesuretomakethesystemrunsteadily,easyandsimpletohandle,solveandhittheproblemactually,guaranteetosupplywaterofthesecurity,swift,reliable.Constantvoltagehassuppliedwaterandguaranteedtosupportthewaterqualityamount,thecontrolsystemtakingPLCashostcomputerhasenrichedthesystematiccontrolfunction,haveimprovedsystematicdependability.Keyword:PLC(programmablecontroller),Constantvoltage,supplieswater,Frequencyconverter目录第一章绪论..............................................................................................................11.1变频恒压供水产生的背景和意义......................................................................11.2变频恒压供水系统的国内研究现状ﻩ11.3本文研究的系统组成和工作原理ﻩ2第二章PLC概述.....................................................................................................32.1PLC介绍..............................................................................................................32.2PLC工作原理...................................................................................................42.3PLC的编程语言ﻩ62.4PLC的分类.......................................................................................................92.5PLC控制系统的结构ﻩ10第三章系统硬件的设计.......................................................................................133.1恒压供水系统的基本构成...........................................................................153.2系统控制要求ﻩ713.3控制系统的I/O点及地址分配....................................................................183.4系统选型ﻩ193.5PLC模拟量控制单元的配置以及应用ﻩ91第四章系统程序设计..........................................................................................254.1由“恒压”要求出发的工作泵组数量控制管理................................