基于PLC的压供水控制系统设计.doc

基于PLC的恒压供水控制系统设计 摘 要 随着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。 本论文根据中国城市小区的供水要求，设计了一套基于PLC的变频调速恒压供水系统。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。再经过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 Water Supply Control System of Constant Pressure Based on 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. 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. 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. In this paper，the control principle of VVVF providing-water system is introduced，we use PLC to carry on logic control and use inverter to modulate pressure．Through PID control principle .we realize Closed-loop control in VVVF Providing-water System．The result indicates that the system has the stable pr