基于PLC的恒压供水系统控制论文方案设计书.docVIP

摘 要 随着社会经济的迅速发展，人们对供水质量和供水系统可靠性的要求不断提高;再加上目前能源紧缺，利用先进的自动化技术、控制技术以及通讯技术，设计高性能、高节能、能适应不同领域的恒压供水系统成为必然趋势。本论文结合我国中小城市多层住宅小区的用水现状，设计了一套基于PLC的变频调速恒压自动控制供水系统。 变频调速恒压供水自动控制系统由可编程控制器、内置PID变频器、水泵电机组、压力传感器、及控制柜等构成。 在变频调速恒压供水系统中，单台水泵工况的调节是通过变频器来改变电源的频率 来改变电机的转速 ，从而改变水泵性能曲线得以实现的。分析水泵工况的能耗比较图，可以看出利用变频调速实现恒压供水，当转速降低时，流量与转速成正比，功率以转速的三次方下降，与传统供水方式中用阀门节流方式相比，在一定程度上可以减少能量损耗，能够明显节能。 本控制系统中采用了德国SIMENS公司的S7-200可编程控制器，同时选取了一个用于供水系统压力控制的内置PID算法的变频器。该变频器对压力给定值与测量值的偏差进行处理，实时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来改变水泵出水口流量，实现管网压力的自动调节，使管网压力稳定在设定值附近。 关键词：PLC；恒压供水；变频调速 Abstract With the rapid socio-economic development, people on the reliability of water quality and water supply systems have higher requirements; coupled with the current energy shortage, the use of advanced automation technology, control technology and communication technology, design high-performance, high energy, able to adapt Water Supply System in different fields has become an inevitable trend. This paper combines the small and medium cities in Chinas water status residential area, designed a PLC-based control water supply system frequency control. Frequency Control Constant Pressure Water Supply Control System consists of a programmable controller, built-in PID inverter, water pump turbine, pressure sensors, and control cabinet composition. In the frequency control water supply system, a single pump operating conditions by adjusting the frequency converter to change the power to change the motor speed, thus changing the pump performance curve can be realized. Analysis of the energy consumption of pump condition comparison chart, you can see using frequency control constant pressure water supply, when the speed decreases, the flow and speed is proportional to the cube of power to speed down, and traditional water supply using the valve section flow method, compared to a certain extent, reduce energy consumption, energy saving can be significant. The control system used in the company of the German SIMENS S7-200 programmable cont