基于PLC和变频器的恒压供水自动控制系统设计.doc

内蒙古科技大学 本科生毕业设计说明书（毕业论文） 题 目：基于PLC和变频器的恒压供水自动控制系统设计 学生姓名：杨蓉 学 号：200440503237 专 业：测控技术与仪器 班 级：测控2004-2班 指导教师：李忠虎 副教授 基于PLC和变频器的恒压供水自动控制系统设计 摘 要 随着社会的发展本论文，设计了一套基于PLC恒压供水系统。变频调速恒压自动控制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、及控制柜等组成。系统采用一台变频器拖动四台电机的运行、启动、调速。其中台大机台小机采用循环使用的方式运行。在变频调速恒压供水系统中，单台水泵工况的调节是通过变频器实现的。分析水泵的能耗比较图，可以看出利用变频器实现调速恒压供水，当转速降低，流量与转速成正比，功率以转速的三次方下降，与传统供水方式阀门节流控制相比，在一定程度上可以减少能量损耗，。该系统能够对供水系统进行自动控制，有效的降低能耗系统维持在最佳运行状态，提高生产管理水平。 关键词：Automatic control system of constant press water supply based on converter and PLC Abstract With the developement of society,it demands higher and higher water supply quality,both in producing and living. However,one of the important guide lines of the water supply quality is offer the relatively steady water supply hydraulic pressure.Therefor, the paper closely combines actuality of water supply and designs a suit of constant pressure water supply automatic control system based on variable frequency speed-regulating technology and PLC. The constant pressure water supply automatic control system is made up of PLC,transducer,pump assembling unit,pressure sensor,industrial control computer and console.The system used a transducer to make four electromotors starting,running,and timing. The three high-power electromotors and one low-power electromotors are circulated running. In the system, water pump’s start stop and workings switch are controled by PLC.Single water pum’s working condition is adjusted by transducer.After analyzing the figure of energy wasting of pump ,we know when using transducer timing constant water supply, rotate speed lower,flux and rotate speed is direct proportion,the power of electromotor drop three cube of rotate speed. So the energy wasting of constant pressure water supply based on variable frequency speed regulation technology is evident less than the traditional mode is used throttle to supply water. This water supply system can control automationally,reduce the energy consumption effectively,kee