毕业设计---基于PLC的变频调速恒压供水系统

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1、 摘要摘要 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

2、了运行状态动态显示及数据、报警的查 询。 关键词关键词：变频调速，恒压供水，PLC，组态软件 ABSTRACT According to the requirement of Chinas urban water supply, this paper designs a set of water supply system of frequecey control of constant voltage based on PLC, and have developed good operation management interface using Supervision Control a

3、nd Data Acquisition.The system is made up of PLC, transducer,units of pumps,pressure sensor and control machine and so on. This system is formed by three pump generators,and they form the circulating run mode of frequency conversion. With general frequency converter realize for three phase pump gene

4、rator soft start with frequency control,operation switch adopts the principle of”start first stop first”. The detection signal of pressure sensor of hydraulic pressure,via PLC with set value by carry out PID comparison operation,so,control frequency and the export voltage of frequency converter,and

5、then the rotational speed that changes pump generator come to change water supply quantity,eventually,it is nearby to maintain pipe net pressure to stabilize when set value. Through work control machine the connection with PLC,with group form software consummately systematic monitoring,have realized

6、 operation state development to show and data,report to the police inquiry. Keywords: variable frequency speed-regulating, constant-pressure water supply, PLC, supervision control and data acquisition. 目录目录 1 绪论 .1 1.1 课题的提出 .1 1.2 变频恒压供水系统的国内外研究现状 .3 1.3 PLC 概述5 1.4 本课题的主要研究内容 .7 2 系统的理论分析及控制方案确定 .8 2.1 变频恒压供水系统的理论分析 .8 2.2 变频恒压供水系统控制方案的确定 . 11 3 系统的硬件设计19 3.1 系统主要设备的选型 .19 3.2 系统主电路分析及其设计 .23 3.3 系统控制电路分析及其设计 .25 3.4 PLC 的 I/O 端口分配及外围接线图 27 4 系统的软件设计31 4.1 系统软件设计分析 .31 4.2 PLC 程序设计33 4.3 PI