石家庄铁道学院毕业设计(论文)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、工控机等构成。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PLCI石家庄铁道学院毕业设计(论文)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-regulatingConstant-pressurewatersupplyPLCII石家庄铁道学院毕业设计(论文)目录第一章绪论.........................................................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.............................21.3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.................................42.1变频恒压供水系统的理论分析...................................42.1.1电动机的调速原理.......................................42.1.2变频恒压供水系统的节能原理.............................42.2变频恒压供水系统的理论分析...................................52.2.1控制方案的比较和确定...................................52.2.2变频概述...............................................62.2.3变频恒压供水系统的组成和原理图.........................72.2.4变频恒压供水系统控制流程...............................92.2.5水泵切换条件...........................................9第三章系统的硬件设计..............................................113.1系统主要设备的选型..........................................113.1.1控制方案的比较和确定..................................113.1.2西门子S7-200PLC简介..................................133.1.3PLC及其模块的选型....................................143.1.4变频器的选型..........................................143.1.5水泵机组的选型........................................153.1.6压力变送器的选型......................................153.1.7液位变送器的选型......................................163.2系统主电路分析及其设计......................................163.3系统控制电路分析及其设计....................................1...
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