(变频器一拖四系统.doc

摘要 日常的生活用水量随季节、昼夜、上下班的时间不同而有较大变化，因而经常出现供水用水的不平衡，主要表现在水压上，用水多而供水少则水压低，用水少而供水多则水压高。住宅区由于自来水管网的水压较低，自来水通常不能到达住宅的较高楼层。 Abstract The daily domestic water quantity along with the season, diurnal, the coming and going to work time different has comparatively sweeping change, thus frequently appears the water supply water used not to be balanced, mainly displays in the hydraulic pressure, with juicy supplies water few then the water pulls down, the water used few supplies juicy then height of water. The residential district because the running water pipe network hydraulic pressure is lower, the running water usually can not arrive the housing a higher floor.Along with the city scale unceasing expansion and the urban population suddenly inflation as well as the city industry high speed development, the city suddenly is growing with the water volume. In order to enable each city peoples all with ease conveniently to use the pure running water, the pump house control system has become in the entire water works dispatcher and the supervisory system the very important link. In order to solve the instability of the water supply pressure and improve the quality of water一supplying, a kind of constant pressure water supply system with changing frequency and speed abilities base on S7-200 and BT12S inverter is designed. Its structure and working principle are firstly introduced，the design of the control systerms hardware and sofaware is then detailed and the advantages of the system are lastly summed up. The system in practice proves to have batter reliability and economy. Keywords: Converter,PLC,PID ,Constant pressure water-supplying,Advandage0 引言 自从通用变频器问世以来，变频调速技术在各个领域得到了广泛的应用。变频调速恒压供水设备以其节能、安全、高品质的供水质量等优点，在实际应用中发挥了很大的作用。变频调速恒压供水系统主要由水泵组、循环软启动变频柜、压力仪表、管路系统等组成。变频柜由变频调速器、PLC 、低压电器等构成。变频器的作用是为电机提供可变频率的电源，实现电机的无级调速，从而使管网水压连续变化。传感器的作用是检测管网水压，压力设定单元为系统提供满足用户需要的水压期望值。一般来说有两种控制方式，一种控制方法是压力设定信号和压力反馈信号在输入可编程控制器后，经可编程控制器内部PID运控制程序的计算，输出给变频器一个转速控制信号。另一种控制方法是将压力设定信