基于PLC的变频调速恒压供水系统 毕业论文.doc

- PAGE 1 - 摘要 本论文根据中国城市小区的供水现状：供水压力低，无法满足高层用户用水的要求，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，并利用组态软件开发良好的运行管理界面及PID控制器，满足了用户对恒压供水系统的要求。 在电机总功率确定的条件下，采用三台电机分别拖动水泵，组成变频循环运行方式，达到节能效果。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，实现了运行状态动态显示及数据、报警的查询等管理功能。该设计对其他需要恒压液体传输的管网也具有重要的参考价值。 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 and 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 generator 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 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 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 TOC \o 1-3 \h \z 摘　　要 1 Abstract 2 引　　言 3 1概述 4 1.1本课题研究的目的和意义 5 1.2本文主要的研究内容 5 2变频恒压供水系统的理论分析 6 2.1变频调速的原理 6 2.2水泵调速运行的节能原理 6 2.3供水压力和变频器输出频率的关系 6 2.4变频恒压控制的理论模型 6 2.4.