基于plc的变频恒压供水控制调速系统设计

恒压供水PLC控制变频调速系统设计

随着改革开放的不断深入，我国中小城市的城市建设及其经济迅猛发展，人民的生活水平不断提高；同时，城市需水量日益加大，对城市供水系统提出了更高的要求。供水的可靠性、稳定性、经济节能性直接影响到城区的建设和经济的发展，也影响到城区居民的正常工作和生活。本文根据城区供水管网改造工程设计了一套由PLC、变频器、远传压力表、多台水泵机组、计算机等主要设备构成的全自动变频恒压供水及其远程监控系统，具有自动工频/变频恒压运行、可实现远程自动控制和现场手动控制等功能。论文分析了采取变频调速方式实现恒压供水相对于传统的阀门控制恒压供水方式的节能机理。通过对变频器内置PID模块参数的预置，利用远传压力表的水压反馈量，构成闭环系统，根据用水量的变化，采取PID调节方式，在全流量范围内利用变频泵的连续调节和工频泵的分级调节相结合，实现恒压供水且有效节能。论文论述了采用多泵并联供水方案的合理性，分析了多泵供水方式的各种供水状态及转换条件，分析了电机由变频转工频运行方式的切换过程及存在的问题。给出了实现有效状态循环转换控制的电气设计方案和PLC控制程序设计方案。系统有效地解决了传统供水方式中存在的问题，增强了系统的可靠性。并与计算机实现了有机的结合，提升了系统的总体性能。

关键词：PLC；变频调速；恒压供水；变频工频切换

With the continuous deepening of reforming and opening up, the construction and economy of small and medium-sized cities in China have developed rapidly. People's living standards have improved constantly. The water supply system is demanded more as city water consum ption increasing. The urban construction and economic development and also people’s daily work and life are impacted directly by the relia bility, stability and the economical of energy conservation of the water supply system.An autom atic conversion and voltage constant Water Supply and remote monitoring system, which consist of the PLC, the converter, the remote transition pressure gauges, the multi-pumps unit, the computer and so on. It is of automatic line-frequency /conversion function, remote and local automatic control. In this paper, the mechanism of energy saving, which uses speed governing with invertor to design voltage constant water supply system, competing with traditional valve controlled pressure constant system. Closed loop system is built by presetting the parameter of the PID inside of convertor, and feedback of remote transiton hydraulic meter. Using the step regulation of convertor pump and frequency pump in full rang of flow to apply PID control on the change of water achieves energy saving of voltage constant water supply. This paper discusses the reasonability of water supply scheme with much pump parallel connection, and analyses the conversion condition and the various states of water supply of the much pump way of water supply as well as the switch process and the problem of a generator from variable frequency operation mode to work frequency operation mode. In addition，the combination of the system and the computer is achieved，which improved the overall function of the system．

Key words：PLC; Variable Velocity Variab le frequency; Constantp ressure water-supply; variable frequency to working frequency

目录

第一章绪论 (1)

第一节课题背景及意义 (1)

第二节变频恒压供水的现况 (1)

第三节变频恒压供水系统的特点 (3)

第二章变频恒压供水系统理论分析 (4)

第一节供水系统的基本特性 (4)

第二节不同控制方式下的能耗分析与比较 (5)

第三节变频恒压控制的理论模型 (6)

第四节供水系统中的水锤效应 (7)

第三章供水系统恒压控制与硬件设计 (7)

第一节异步电动机调速方法及选择 (7)

第二节供水系统的方案确定 (10)

第三节控制系统的硬件设计与选型 (12)

第四节系统可靠性措施 (21)

第四章PLC 控制程序 (22)

第一节水泵工频/变频运行状态及转换过程分析 (22)

第二节PLC 程序设计方法 (24)

第三节供水系统控制程序 (25)

第五章恒压供水系统的 PID 调节 (27)

结论 (29)

附录A (30)

致谢 (32)

参考文献 (33)