基于PLC控制的变频调速恒压供水系统设计论文_精品.doc

摘 要 随社会经济的迅速发展，人们对供水质量和供水系统可靠性的要求不断提高；再加上目前能源紧缺，利用先进的自动化技术、控制技术以及通讯技术，设计高性能、高节能、能适应不同领域的恒压供水系统成为必然趋势。 本设计是针对居民生活用水而设计的。由变频器、PLC、PID调节器和组成控制系统，调节水泵的输出流量。电动机泵组由三台水泵并联而成，由变频器或工频电网供电，根据供水系统出口水压和流量来控制变频器电动机泵组的速度和切换，使系统运行在最合理状态，保证按需供水。 ? 本文介绍了采用PLC控制的变频调速供水系统，由PLC进行逻辑控制，由变频器进行压力凋节。在经过PID运算，通过PLC控制变频与工频切换，实现闭环自动调节恒压变量供水。运行结果表明，该系统具有压力稳定，结构简单，工作可靠等特点。 关键词：变频调速 ；恒压供水；PID调节；PLC ABSTRACT With the rapid development of social economy； it demands the better of water supply s quality and reliability of water supply system. Meanwhile energy resources are seriously lack. So it is inevitable tendency to design water supply system which has high function and saves on energy well， with help of advanced technique of automation， control and communication. At the same time this system can adapt different water supply fields.It is very important of the Water Supply System in Constant Pressure for the water supply in industrial and citizen existence. It is consist of the variable frequency and speed regulation， PLC， PID control system for the control system. It controls the outcome of the pumps. The generator pumps are consist of parallel three pumps， and the power come from variable frequency and speed regulation or power grid. According to the water supply of constant pressure’s outcome water press and flux， the control system control the variable frequency and speed regulation， parallel pumps’ speed and cut over， cause the system move in the best rational situation， assure according to wants supply water. This design has many merits such as save energy.Keywords： variable frequency and speed regulation；water supply of constant pressure；PID control system 目录 摘 要 1 ABSTRACT 2 1 绪论 1 1.1变频恒压供水产生的背景和意义 1 1.2变频恒压供水系统的国内研究现状 3 1.3课题来源及本文的主要研究内容 5 1.4本论文中所做的工作 5 2 恒压供水系统的基本构成 6 3 变频器和压力传感器 8 3.1 变频器的基本结构 8 3.2 变频器的分类及工作原理 11 3.3 变频器的操作方式及使用 12 3.4 变频器硬件选择 13 3.5 压力传感器 14 4 PLC选择及应用 16 4.1 PLC在恒压供水泵站中的主要任务 16 4.2 PLC模拟量扩展单元的配置及应用 16 4.2.1 模拟量输入模块的功能及与PLC系统的连接………………………….17 4.2.2 模拟量输入模块缓冲