毕业设计题目城市小区恒压供水系统
摘要
我国人口众多，每年所消耗的能量巨大。近年来，能源紧张影响到工业生产及人民生活。因此，节能降耗是保证工业和生活稳定发展的一项关键措施。然而，长期以来，由于我国自动化程度低，用水行业的技术水平相对比较落后，经常导致用水高峰期用户用水的不稳定，例如水压较低，供水量低于需求量。因此针对小区居民的日常用水问题，设计了一套基于PLC控制的变频调速恒压供水系统。
此变频调速恒压供水系统由PLC、变频器、压力变送器等组成，由一台变频器实现对三台水泵电机的软启动和变频调速，三台泵电机采用变频和工频循环运行方式，运行切换采用“先启先停”的原则。使用STEP7 Micro/WIN编程软件，设计了一个用于供水系统压力控制的控制器内置在PLC中，对压力给定值与测量值的偏差进行处理，从而控制变频器的输出电压和频率，进而改变水泵电动机的转速和水泵出水口流量，实现管网压力的自动调节，使管网压力稳定在设定值附近，并且利用组态软件设计了系统的用户管理和监控界面。
关键词：变频调速；恒压供水；可编程控制器
Abstract
For the numerous population, much energy is consumed every year in our country．In recent years, shortage of source have affected the industrial production and people's life.Therefore, energy saving and reduce the consumption is a crucial measure to guarantee industry and life's stable development.However,since automation level is low ,for a long time,our country falls behind with the technical horizon comparison with water profession, users often appears with the instability of water in using water peak-hour,such as hydraulic pressure is low and the supply of water is measured below demand. According to the problem in using water designed a variable frequency speed-regulating constant pressure water-supply system with PLC .
The water supply system consists of PLC,frequency converter and pressure transmitter etc.A frequency converter to realize three phase pump generator's soft start and frequency control, three pump generators to comprise the circulating run mode of frequency conversion, operation switch adopts to the principle of"start first stop first".using STEP7 Micro/WIN program software designed a control system with PLC .The control system can compare the measured pressure with the advanced pressure , to control the real-time output Voltage and frequency.the output quality of pump is changed along with the changing of pump's speed.It makes the pressure of pipe self-regulating and steady in the scheduled value,and have designed a operation management interface using Supervision Control and Data Acquisition.
Key Words：variable frequency speed-regulating；constant pressure water-supply；programmable logical controller
目录
第一章绪论 (1)
1.1 变频恒压供水系统研究的技术背景和设计依据 (1)
1.2 变频恒压供水系统国内外的研究现状及发展趋势 (2)
1.3 可编程控制器简介 (3)
1.4 本文研究的主要内容 (6)
第二章变频恒压供水系统分析 (7)
2.1 供水系统的基本特性和方式 (7)
2.2 常用调速方式及变频调速原理 (9)
2.3 变频调速技术 (11)
2.4 水泵调速运行的节能原理 (12)
2.5 变频恒压供水的特点分析 (13)
第三章基于变频调速的恒压供水系统设计 (15)
3.1 变频调速恒压供水系统要完成的主要功能 (15)
3.2 变频调速恒压供水系统的控制方案及选择 (15)
3.3 变频调速恒压供水系统的构成 (17)
3.4 变频调速恒压供水系统工作原理 (19)
3.5 变频至工频的同步切换 (20)
3.6 变频调速恒压供水系统运行分析 (21)
第四章系统硬件设计 (22)
4.1 变频器的选择 (22)
4.1.1 MM440型变频器性能特点及技术指标 (23)
4.1.2 MM440型变频器的主要作用 (24)
4.1.3 MM440型变频器的电路结构 (25)
4.1.4 MM440型变频器的参数设定和调试 (26)
4.2 水泵的选择 (27)
4.3 其他相关设备的选择 (29)
4.3.1 变送器的选择 (29)
4.3.2 接触器的选择 (30)
4.3.3 软启动器的选择 (31)
4.3.4 主令电器的选择 (32)
4.4 系统电路设计 (33)
4.4.1 主电路设计 (33)
