摘 要：随着经济和社会的不断发展，供水系统已在人们的日常生产生活中成为不可或缺的重要部分，在能源相对短缺以及国家倡导节能减排的大背景下，要求供水系统的高节能性和高可靠性就成为必然趋势，供水系统在恒压变频上的研究也就成为价值较高、意义较大的研究课题之一。本论文阐述了供水系统的基本组成，供水系统的现状，设计了一套由PLC、变频器及三台水泵组成的恒压供水控制系统，既可以实现通过变频泵的连续调节，也可实现工频泵的分级调节，且采用内置 PID 环节，水压波动小，确保恒压供水；该系统能够对泵组实现自动化控制从而实现变频恒压供水，一定程度上解决了稳定性和资源浪费问题。 68628

毕业论文关键词：恒压供水，PLC，变频器

Abstract：Along with the continuous development of economy and society, the water supply system has been in the people's daily production and life become an indispensable important part, the relative shortage of energy and the national advocate energy-saving emission reduction under, high energy efficiency and high reliability of the water supply system has become an inevitable trend, water supply system Research on frequency conversion and constant pressure has become one of the higher value and significance of the larger research topic. This paper describes the basic composition of the water supply system, the status of water supply system, a set composed of PLC, inverter and three pump constant pressure water supply control system, can achieve through the continuous adjustment of the frequency conversion pump, achieved classification of the pump frequency adjustment and using built-in PID link, small pressure fluctuation to ensure constant pressure water supply; the system can of pump group realize automation control variable frequency constant pressure water supply, extent solve the stability and the problem of waste of resources.

Key words:The constant pressure water supply; PLC; The inverter

目  录

1 引言 4

1.1 PLC概述 4

1.2 传统供水系统介绍 5

1.3 现代供水系统介绍 6

1.3.1 国外现代供水系统 6

1.3.2 国内现代供水系统 6

2 变频恒压供水系统控制原理 7

2.1 PLC变频恒压供水系统基本组成 7

2.2 PLC变频恒压供水系统基本结构及原理 7

2.3供水系统的基本特性和工作特点 9

2.4变频调速原理 10

2.5 变频恒压节能原理 10

2.6 PID控制算法的一般形式 11

3 变频恒压供水系统控制方案确定 12

3.1 供水系统控制流程 12

4 硬件选型及设计 14

4.1 PLC选型 14

4.2 电气主电路设计 14

4.3 I/O接线图 15

4.3.1 可编程逻辑控制器(PLC)的I／0端子分配 15

5 软件设计 17

5.1系统流程图设计 17

5.2 系统水泵运行状态分析 17

5.3 PID控制器设计