恒压供水系统毕业设计说明书.docx

内蒙古科技大学毕业设计说明书(毕业论文)

恒压供水系统设计

摘要

建设节约型社会，合理开发、节约利用和有效保护水资源是一项艰巨任务。由于传

统供水方式的缺陷，本文设计了一套PLC控制的变频调速恒压供水系统。

恒压供水是指在供水网系中用水量发生变化时，出口压力保持不变的供水方式。系统由可编程控制器、变频器、水泵电机组、压力变送器等构成。共三台电机，其中由一台变频器拖动2台电动机的起动、运行与调速，1台电机备用。控制系统中采用德国SIEMENS公司的S7-300可编程控制器来控制水泵电机的投入台数及运行方式；同时利用其中的数字PID控制器，由FB41将压力给定值与测量值的偏差进行处理，实时控制变频器的输出频率，进而改变水泵电动机的转速来改变水泵出水口流量，实现管网压力的自动调节，使管网压力稳定在设定值附近。此方法具有短路保护、过载保护功能，工

作稳定可靠，大大延长了电机的使用寿命。

关键词：PLC;变频调速；恒压供水

内蒙古科技大学毕业设计说明书(毕业论文)

TheConstantPressureWaterSupplySystemDesign

Abstract

Buildingtheconservation-orientedsociety,thereasonabledevelopment,savesandtheeffectiveprotectingwaterresourcesisanarduoustask.Asaresultoftheflawofthetraditionwatersupplysystem,asetofPLCcontrolsfrequencyconversionvelocitymodulationconstant

pressurewatersupplysystemisdesigned.

Constantpressurewater-supplymeansthatthewatersupplynetworksintheeventofchangeablewaterconsumption,buttheexportsstillremainthesamepressure.ThecomponentofthissystemincludesthePLC,tranducer,pumpmotorgroup,andthepressuresensor.Thisdesignusesonetransducerdrivers2Motorsstarting,runningandspeedcontrol.Anothermotorisusedtobereserved.ThecontrolsystemusedS7-300programmablecontrollerwhichbemadeinGermanySIMENScorporation.ThroughthePIDcontrollers,pressurewillbegiventhefixedvalueandprocessingerrorofthemeasurementbyFB41.Usingthecontrollerstocontrolthevoltageandfrequencyofthefrequencyconverterinreal-timeandthenchangethepumpmotorSpeedtochangethepumpoutletflow,thepressureonthepipenetworktoachieveautomaticadjustmentsothatthepressurepipelinenetworksettingsstabilityinthevicinity.theauxiliarypumpsoftstart,hastheshortcircuitprotection,theoverflowprotection

functionstably,theworkreliable,lengthenedelectricalmachinerysservicelifegreatly.

Keywords:PLC;constantpressurewater-supply;variablefrequencyspeed-