基于三菱PLC的恒压供水系统（毕业论文）.doc

摘要 随着我国社会经济的发展,住房制度改革的不断深入,人们生活水平的不断提高,城市中各类小区建设发展十分迅速,同时也对小区的基础设施建设提出了更高的要求。小区供水系统的建设是其中的一个重要方面,供水的经济性、可靠性、稳定性直接影响到小区住户的正常生活和工作,也直接体现了小区物业管理水平的高低。传统的恒速泵加压供水、水塔高位水箱供水、气压罐供水等供水方式普遍不同程度的存在效率低、可靠性差、自动化程度不高等缺点,难以满足当前经济生活的需要。 本论文针对某住宅小区的供水要求,设计了一套由PLC、变频器、压力变送器、多台水泵机组等主要设备构成的全自动变频恒压供水及其监控系统,具有全自动变频恒压运行、自动工频运行和现场手动控制等功能。系统有效地解决了传统供水方式中存在的问题,并具有多种辅助功能,增强了系统的可靠性。 基于水泵供水流量和水泵转速的三次方成正比,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,利用压力变送器的水压反馈量,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。 关键词:恒压供水；PLC；变频调速Abstract Long with the development of the socio-economy of our country, the housing system is going deep into reforms, and people’s living standard is being improved. At the same time, in the city, each kind of sub-district construction is developing very quickly, which puts forward higher requirement for the infrastructure construction of sub-district. And the construction of sub-district water supply system is an important aspect in which. The reliability, stability and economy of water supply directly affects sub-district household’s normal life and work and also embodies the difference in the level of sub-district property management. The traditional means of water supply such as the pump pressurization water supply at constant speed, water tower of upper cistern, the jar etc. are hard to satisfy the needs of current economic life, because low efficiency, reliability and automation level are all commonly existing in these means. According to the requirement of water supply in a set of automatic system of constant pressure water supply by using variable frequency and remote monitoring and controlling, which is composed of PLC, transducer, Pressure sensor, pumps and electro-motors. This set of system has the functions like automatic constant pressure operation by using variable frequency, automatic work frequency operation and the on-the-spot control by hand etc. T