文档介绍：基于LONWORKS技术的空调自控系统设计
摘要
目前,变风量(VAV)空调系统以其巨大的节能潜力逐渐成为国内外空调系统的主流。
本文通过对变风量空调实验系统的控制原理分析,结合设计要求,设计了以LONWORKS现场总线技术为主的控制网络体系,在设计中分别选取了六个LONWORKS的输入、输出模块,来完成信号的传递和模块间的相互通讯,其中每个输入模块(送风温度、管道静压、二氧化碳浓度)对应一个输出模块(水阀开度、变频器频率、新风阀开度),传感器将现场信号传给输入模块,输入模块再通过双绞线传送至输出模块,由输出模块中的PID控制器运算后,输出一个控制量给执行机构,完成了现场控制功能。这样,不仅节省了导线成本,控制起来也更加及时方便,使控制系统更有保障。另外,在系统的上位机运用了组态王软件,并结合LONMAKER FOR WINDOWS软件设计监控画面,实现系统的全程监控。
在对系统送风温度控制回路的调节器的参数进行整定时,使用了史密斯预估补偿法来克服纯滞后环节对系统带来的影响;整定VAV末端串级控制回路,采用“先内后外”的原则, 并结合临界比例度整定法对系统进行了整定。此外,本文还运用了单纯型法对PID参数进行优化,使得调节效果更加显著。
关键词:变风量空调,LonWorks技术,史密斯预估补偿,
寻优
Design of Automatic Control in VAV System
Based on LonWorks Technology
Abstract
Nowadays, VAV air-conditioning system has gradually e most popular in China and abroad because of its significant energy saving.
According to analyzing the principle of control on VAV experimental system bining with the designing requirement,we select six input and output module of LonWorks, plete the transmission of the signal and munication among the modules. One input module (air flow temperature, pipeline static pressure, carbon dioxide density) correspond to one output module (open degree of water valve, frequency of converter, open degree of new air flow valve). The transducers send the on –the- spot signals to input modules, and then the input modules send it to output modules through the twist wire. These signals, which are operated by PID controller, are conversed into control signals. The control signals can drive actuator plete the on-the-spot control. In this way , not only the cost of the wire can be saved, but also the control of the system can e more convenient , make the control system more safe. In addition, we use Kingview and LonMaker for Windows soft ware designing the monitoring man-machine interface to monitor the whole system.
When setting the parameters of the controller in the air flow temperature control loop, we select Smith predictor to e disturbing, which was induced by delay links of the loop