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,并利用组态软件开发良好的运行管理界面。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、工控机等构成。本系统包含三台水泵电机，它们组成变频循环运行方式。采用变频器实现对三相水泵电机的软启动和变频调速，运行切换采用“先启先停”的原则。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，组态软件ABSTRACTAccordingtotherequirementofChina'surbanwatersupply,thispaperdesignsasetofwatersupplysystemoffrequeceycontrolofconstantvoltagebasedonPLC,andhavedevelopedgoodoperationmanagementinterfaceusingSupervisionControlandDataAcquisition.ThesystemismadeupofPLC,transducer,unitsofpumps,pressuresensorandcontrolmachineandsoon.Thissystemisformedbythreepumpgenerators,andtheyformthecirculatingrunmodeoffrequencyconversion.Withgeneralfrequencyconverterrealizeforthreephasepumpgeneratorsoftstartwithfrequencycontrol,operationswitchadoptstheprincipleof”startfirststopfirst”.Thedetectionsignalofpressuresensorofhydraulicpressure,viaPLCwithsetvaluebycarryoutPIDcomparisonoperation,so,controlfrequencyandtheexportvoltageoffrequencyconverter,andthentherotationalspeedthatchangespumpgeneratorcometochangewatersupplyquantity,eventually,itisnearbytomaintainpipenetpressuretostabilizewhensetvalue.ThroughworkcontrolmachinetheconnectionwithPLC,withgroupformsoftwareconsummatelysystematicmonitoring,haverealizedoperationstatedevelopmenttoshowanddata,reporttothepoliceinquiry.Keywords:variablefrequencyspeed-regulating,constant-pressurewatersupply,PLC,supervisioncontrolanddataacquisition.目录1绪论.....................................................................................................11.1课题的提出......................................................................11.2变频恒压供水系统的国内外研究现状...................................................................................................................31.3PLC概述....................................................................................51.4本课题的主要研究内容...................................72系统的理论分析及控制方案确定..............82.1变频恒压供水系统的理论分析..............82.2变频恒压供水系统控制方案的确定...113系统的硬件设计...............................................................193.1系统主要设备的选型......................................193.2系统主电路分析及其设计........................233.3系统控制电路分析及其设计.................253.4PLC的I/O端口分配及外围接线图..........274系统的软件设计...............................................................314.1系统软件设计分析.............................................314.2PLC程序设计..................................................................334.3PID控制器参数整定.............................................405监控系统的设计...............................................................465.1组态软件简介...........................................................465.2监控系统的设计....................................................466结束语...........................................................................................51参考文献.........
