恒压供水系使用统的PLC控制设计初版.doc

摘 要 随着城市经济的发展，城市高楼不断的增高，城市区域不断扩展，城市供水开始出现压力不足的问题，水是人类生活的必须品，传统的供水系统已经不能满足现代城市的需要。需要一个新的供水系统，要保证城市供水的压力恒定，满足用户，并且节约能耗，自动调节，便于维护。 本设计针对上述问题，通过对现代控制技术的研究，对不同的恒压供水系统进行比较和分析，采用变频器结合PLC的控制方案，来解决恒压供水问题。以PLC与变频器控制水泵电机工作，实现运行可靠、节能、低噪，维护简单，经济实用的恒压供水系统。这个系统能自动控制水泵转速，实时读入管网压力值，与设定值比较，由PID控制算法得出一调节参量，控制调速泵的转速，最终实现恒压供水。 关键词 变频器，恒压供水，PLC  ABSTRACT With the development of city economy, increased continuously city building, city expanding regional, city water supply began to appear the pressure of shortage, the water is the human life necessities, traditional water supply system has been unable to meet the needs of modern city. The need for a new water supply system, to ensure the constant pressure of city water supply, satisfy the user, and saves energy consumption, automatic adjustment, convenient maintenance. This paper in view of the above question, through the study of modern control technology, comparison and analysis of different combination of constant pressure water supply system, the control scheme of PLC converter, to solve the problem of constant pressure water supply. PLC and inverter control pump motor, to achieve reliable operation, energy saving, low noise, easy maintenance, constant pressure water supply system is economical and practical. This system can automatically control the pump speed, real-time read into the pipe network pressure value, compared with the set value, controlled by the PID algorithm to obtain a control parameter, control the speed of the pump, the ultimate realization of constant pressure water supply. Keywords：Speed-frequency variable,Constant pressure water supply,PLC  目 录 摘 要 I ABSTRACT II 1 绪论 1 1.1研究背景 1 1.1.1 城市供水需求 1 1.1.2 传统供水系统的比较 1 1.2 恒压供水系统的国内外研究现状 3 1.3 供水系统安全性讨论 4 1.4 本论文主要设计思想 4 2 系统的理论分析及方案的确定 6 2.1供水系统的主要参数 6 2.2供水系统的基本特性 6 2.3变频恒压供水方式的选择 9 2.4变频恒压供水系统的工作原理 10 2.4.1系统的构成 10 2.4.2工作原理 11 2.5变频恒压供水系统中加减水泵的条件分析 12 3 变频恒压供水系统的硬件设计 13 3.1 PLC 13 3.11 PLC简介 13 3.12 PLC的选型 14 3.2 PLC扩展模块EM235 1