基于PLC的液位控制系统设计

毕业论文（设计）题目：基于PLC控制的高精度液位控制系统的设计姓名：濮孝金学号：122120018专业：机械电子工程年月摘要在工农业生产过程中，经常需要对水位进行测量与控制，而日常生活中应用到的水位控制也相当广泛。在以往水塔液位控制系统中，常规继电器的频繁操作容易导致机械磨损，不方便更新和维护，不能满足人们的实际需求；另外，随着人口的递增和生活条件的提高，人们用水的需求量也日益增加。为了提高液位控制系统的质量和效率，节约能源，本次模拟水塔液位控制系统的装置考虑结合可编程逻辑控制器，继电器和传感器等技术，实现液位控制系统的自动控制。本设计使用西门子S7-300PLC可编程控制器作为液位控制系统的核心，配合硬件与软件实现液位控制池液位动态平衡，过高、过低水位报警等功能。主要的实验方法是在水箱上安装一个自动水位测量装置，通过水位变送器检测水箱实际液位并将该液位反馈到PLC控制器，经A/D转换后，所得数据与PLC内部设定数据进行比较，控制器处理数据并发送相应指令改变电机的转速从而控制抽水速率，改变进水量，使水位稳定地保持在设定值附近。此外，通过液位标定计算出控制器输出PIW数值与实际水位的关系，就可以在触摸屏上直观显示实时水位情况。实验结果表明本设计能较好地完成自动液位控制的功能。关键词：水塔液位控制，水位控制，继电器，PLCAbstractInthecourseofroutineindustrialandagriculturalproductionwetheneedtomeasurethewaterlevelandcontrolit.Furthermoreeverydaylevelcontrolapplicationsarequiteextensive,suchashydropower,watertowersandotherwatercontrol.Accordingtothewatersupplysysteminthepast,frequentoperationtowerswillproducemechanicalwearofconventionalrelayconvenientmaintenanceandupdates,thatmeansitcannotmeettheactualneedsofthepeople,andwithGradualgrowthofpopulationandlivingconditions,thedemandforwaterisalsoincreasing.Inordertoimprovethequalityofthewatersupplysystem,energyconservation,soIconsidereduseaprogrammablelogiccontroller,relayandsensortechnology,withhardwareandsoftwaretoachievelowwaterlevelalarm,warningswitchbetweenworkandproceduresmanual/automatictodesignpracticallevelcontroltowerscheme.Icompletedthesetupofthissimulationusingthetankwatertower,basedonSiemensS7-300PLCprogrammablecontrollertankwaterlevelcontrolsystemasthecore.Icompletedawatertanktocompletetheperformancecapabilityaimingatdoinganeedsanalysis.Themainexperimentalmethodusedistoinstallanautomaticwaterlevelmeasuringdeviceonthetank.ThelevelsensordetectingthewatertanktomeasuretheactualwaterlevelandthecontrolmoduletosendinformationtothePLC,viaA/Dconversion,thedataobtainediscomparedwiththesetlevel,thecontrollerprocessesthedataandsendstheappropriatecommandstocontrolthemotorspeedchangepumpingrate,thewaterlevelmaintainedintheproperposition.ThanTouchscreencompletestheleveldisplay,faultalarminformationdisplay,real-timeandhistoricalcurvecurvesshow.Ifthewaterlevelislowerorhigherthanthesetvalue,thehazardwarningsignalwillbeissuedInthispaper,PLCautomaticwatersupplysystembasedongoodexecutionprocesslevelcontrol.Keywords:towerwater;waterlevelcontrol;relays;PLC目录第一章绪论.......................................................................................................................1§1.1研究背景........................................................................................................1§1.2PLC的产生与发展........................................................................................21.2.1PLC的产生................................................................................................21.2.2PLC技术的发展........................................................................................2§1.3设计任务.........................................................................................................3第二章液位控制装置硬件设计.......................................................................................4§2.1自动液位控制系统应用简介........................................................................4§2.2液位控制装置硬件组成.................................................................................5§2.3PLC的基本结构..............................................................错误!未定义书签。2.3.1中央处理单元(CPU)...................................................错误!未定义书签。2.3.2I/O模块..................................................................错误!未定义书签。2.3.3电源模块....................................................................错误!未定义书签。§2.4PLC的工作原理..............................................................错误!未定义书签。2.4.1公共处理扫描阶段....................................................错误!未定义书签。2.4.2输入采样扫描阶段....................................................错误!未定义书签。2.4.3执行用户程序扫描阶段............................................错误!未定义书签。2.4.4输出刷新扫描阶段....................................................错误!未定义书签。§2.5水箱液位控制系统组成及工作原理.............................................................72.5.1液位控制系统结构图：...........................................................................72.5.2液位控制系统工作原理...........................................................................72.5.3液位控制系统工作过程：........................................................................82.5.4水箱液位的标定........................................................................................9第三章液位控制系统软件设计.....................................................................................11§3.1PLC软件程序介绍..........................................................错误!未定义书签。3.1.1梯形图的组成：........................................................错误!未定义书签。3.1.2梯形图的几个特点....................................................错误!未定义书签。3.1.3梯形图的格式............................................................错误!未定义书签。§3.2程序设计流程图...........................................................................................11§3.3PLC中PID控制器的实现..........................................................................113.3.1PID算法..