本科生毕业设计（论文）PAGEIV摘要本系统的主要内容是将PLC控制网络技术、计算机控制技术应用于工程实践中，以人们的生活用水、消防高压用水为被控对象，将PLC控制技术、计算机控制技术、自动化技术融合于系统中。该统改变了以前生活和消防两套独立供水的模式，同时克服了传统有塔有箱供水方式的缺点，是一种节能、占地少、投资小、系统安全可靠、维护和管理方便的供水控制系统。本系统基于变频器内置Pm调节系统，以管网的压力变送器压力信号作为反馈信号，由上位机发出的当前状态作为给定输出，调节生活供水压力使其保持低恒压状态;当火灾发时，调节系统管网压力为高恒压状态。同时，系统设计考虑了夜间低流量状态下，水泵机组停运行，由气压罐进行低流量供水，保证了系统避免频繁启停，同时保证水泵的高效运行。基于供水系统和消防系统构筑了一个DCS集散系统。2台变频器和PLC作为下位机设备，工控机作为上位机集中控制，上下位机之间通过通讯，把系统当前状态、当前给定通过上位机来综合判断，并通过上位机以汉化界面形式予以显示，而下位机的变频部分则实现管网的恒压功能，PLC实现4台水泵机组逻辑控制和定期巡检，及部分故障综合报告。关键词：生活和消防用水；恒压；通讯AbstractThemaincontentofthisthesisisthepracticeforusingprogrammablelogiccontroller(PLC)andcomputercontroller.ThesystemcombinesthePLC,computercontroller,andautomatictechnologyinordertocontrolthelivingwatersupplyandfirefightingwatersupply.Thesystemiswiththevirtueofenergysaving,smallervolume,lowerinvestment,higherreliabilityandeasierformaintenanceandmanagecomparedwiththetraditionalwatersupplymethodwithtowerandbank.ThesystemisbasedontheinnerPIDregulatefunctionoffrequencyconvertertoregulatethelivingwaterstresswithlowconstantstress,andthestresssignalissensedbythestresstranslatorasfeedbacksignalandtheconstructionissentbythecomputerasthegivensignal.Thewaterstressisregulatedtohighconstantstresswhenthefirehappens.Thesystemisalsodesignedtosupplythewaterbyairpotwithlowfluxatnightwhenthedemandofwaterdecreasesandpumpisstopped.ThedesignavoidsthesystemworkingandpausingfrequentlyandassuresthesystemworkingwithhighefficiencyAdistributedcontrolsystemisbuiltbasedonthewatersupplyingsystemandthefirefightingsystem.TwoABBfrequencyconvertersandaSiemensprogrammablelogiccontroller(PLC)arewiththelower-levelcomputerandIndustrycomputerarewiththehostcomputer.Thecommunicationbetweenwiththehostcomputerandlow-levelcomputernotonlytranslatethesystemcondition,butalsosendthecontrolinstruction.ThesystemconditionisshownwithChinesewindowinthehostcomputer,andtheconstantstressfunctionisrealizedthroughthefrequencyconverterpart.ThePLCcontrolsthesystemlogicandcheckthesystemwithconstantper