恒压供水系统设计..doc

恒压供水系统设计 摘要 建设节约型社会，合理开发、节约利用和有效保护水资源是一项艰巨任务。设计了一套PLC的变频调速恒压供水系统。 恒压供水是指在供水网系中用水量发生变化时，出口压力保持不变的供水方式。系统由可编程控制器、变频器、水泵电机组、等构成。一台变频器拖动2台电动机的起动、运行与调速，1台电机备用。控制系统中采用德国SIMENS公司的S7-00可编程控制器利用PID控制器，将压力给定值与测量值的偏差进行处理，实时控制变频器的输出频率，进而改变水泵电动机的转速来改变水泵出水口流量，实现管网压力的自动调节，使管网压力稳定在设定值附近。具有短路保护、保护功能，工作稳定可靠，大大延长了的使用寿命。关键词： PLC；变频调速；恒压供水 he Constant Pressure Water Supply System Design Abstract Building the conservation-oriented society, the reasonable development, saves and the effective protecting water resources is an arduous task. As a result of the flaw of the tradition water supply system, a set of PLC controls frequency conversion velocity modulation constant pressure water supply system is designed. Constant pressure water-supply means that the water supply networks in the event of changeable water consumption, but the exports still remain the same pressure. The component of this system includes the PLC, tranducer, pump motor group, and the pressure sensor. This design uses one transducer drivers 2 Motors starting, running and speed control. Another motor is used to be reserved. The control system used S7-300 programmable controller which be made in Germany SIMENS corporation. Through the PID controllers, pressure will be given the fixed value and processing error of the measurement by FB41. Using the controllers to control the voltage and frequency of the frequency converter in real-time and then change the pump motor Speed to change the pump outlet flow, the pressure on the pipe network to achieve automatic adjustment so that the pressure pipeline network settings stability in the vicinity. the auxiliary pump soft start, has the short circuit protection, the overflow protection function stably, the work reliable, lengthened electrical machinerys service life greatly. Key words: PLC; constant pressure water-supply ; variable frequency speed-regulating 目录 摘要 I Abstract II 第一章 绪论 1 1.1 课题提出的背景 1 1.2 课题研究的目的和意义 1 1.3 国内外在变频恒压供水系统研究现状及分析 2 1.3.1 变频恒压供水系统的国内外研究现