基于plc的蒸汽锅炉给水泵的控制系统论文.doc

摘 要 近年来电力工业发展迅速，以及能源环保的要求，越来越多的大容量发电机组开始参与调峰运行。锅炉给水泵是火电厂的重要辅机之一，也是电厂的耗能大户，因而给水泵控制系统的先进性直接影响到电厂运行的安全性，研究锅炉给水泵的控制系统具有一定的实用价值。 本文是针对蒸汽锅炉而设计的。由变频器、PLC,PID调节器组成控制系统，调节水泵的给水流量和出水口压力。电动机泵组由两台水泵并联而成，由变频器供电，根据蒸汽锅炉水位变化来控制变频器电动机泵组的速度和切换，使系统运行在最合理状态，保证锅炉水位的稳定。 本文介绍了采用PLC控制的变频调速供水系统，由PLC进行逻辑控制，由变频器进行流量和水位调节。在经过PID运算，通过PLC控制变频与工频切换，实现闭环自动调节流量，水位变量供水。运行结果表明，该系统具有水位控制精度高，结构简单，工作可靠等特点。 关键词：变频调速；PID调节；PLC；锅炉给水泵; ABSTRACT With the rapid development of electric power industry and the necessary demand in protecting the energy,more and more high-capacity power stations are being put into use of operation.Boiler-water-pump is not only one of the important auxiliary parts of heat-engine plant,but also the huge energy custom.What is more,the safety operation of the power station directly depends on the advancement of the water-pump control system .The study of boiler-water-pump control system counts much more value. This paper is aimed at designing the reek boiler.The control system that is made up of frequency transformer,PLC and PID is to regulate the out-put flow and the pressure.The motor pump which consists of one shunt-wound water-pumps absorb the energy from the frequency transformer.According to water level, the motor pump controls the speed and is ready to change when it receives the signal.These make the whole system operates best and ensure the water level is stable. This paper introduces that the frequency-controled water supply system which is controlled by PLC measures the flow and water level through the frequency transformer.After PID counts,the system will make the closed loop automation come true through PLC controlling the switching frequency conversion to power frequency.The results show that the system which it can be relay on can control the water level accurately and its structure is simple. Keywords:frequency conversion speed governing;PID regulated;PLC; Boiler-water-pum ; 目 录 摘 要 I ABSTRACT II 目 录 III CONTENTS V 第1章 绪论 1 1.1选题的背景及意义 1 1.2 国内外研究动态 2 1.2.1