工业锅炉实时液位过程控制系统-.doc

第 PAGE 27页 工业锅炉实时液位过程控制系统 摘 要 锅炉是工业过程中不可缺少的动力设备，为确保安全，稳定生产，对锅炉的自动控制十分重要，其中汽包水位是一个非常重要的被控变量。由于锅炉的水位调节过程难以建立数学模型，具有非线性、不稳定性、时滞等特点。传统的锅炉水位三冲量控制系统大都采用PID控制。本文研究了工业锅炉的计算机控制问题。首先分析了工业锅炉的工艺流程和特点、阐述了调节系统的任务，提出了整体控制方案。在分析了汽包水位回路的动态特性，特别是“虚假水位”产生的原因的基础上，设计了常规PID控制器实现锅炉汽包三冲量控制系统。微分作用对高频干扰十分敏感，容易导致调节品质下降。锅炉本身具有一定的滞后，若不加微分作用，则控制作用的及时性无法发挥。虽然工业锅炉内扰严重，但适当的加一点微分作用对于锅炉水位的控制有一定好处。本文对采用不完全微分型PID的控制情况进行仿真研究，结果表明，控制效果较为理想。 关键词:汽包水位； 三冲量； PID控制 Industrial Boiler-level process control system ABSTRACT Boiler is a necessary power plant in the process of industry. In order to ensure the production and security, the auto-control of it is very important. The drum water level is an important variable to be controlled, it is hard to get the mathematic model of the water level with adjustive process, it is characteristic of nonlinearity, instability and time lag. The traditional control mode of three-variable in the drum water level mostly use PID.The problem of automatic control in industry coal-fired boiler is discussed in this thesis. First of all，the technological process and characteristics of industry boiler is analyzed. The task of boiler regulator is expounded. And then the system scheme of control is presented. The dynamic characteristic of loops for water level is analyzed especially the reason of ostensible water level. On the basis of these a routine PID controller is designed to control the water level. The part of differential is sensitive to high frequency noise, and easily make the quality of adjust declining. Boiler has the characteristic of lag, the controller is not rapid enough if there is not differential item. Althought industrial boilers have many inner-noises, it is good to water level control that properly adds a little of differential item in boiler. This paper studies the simulation of PID control with incomplete differential type, the result of simulation show that the effect is good.Key words: Drum water level； Thr