【作者】 周海君；

【导师】 张根宝；

【作者基本信息】 陕西科技大学 ， 电气与电子工程学院， 2006， 硕士

【摘要】 制浆造纸过程是一个复杂的化工过程,其中涉及到的设备,不论数量还是种类,都是其它多数工业过程所不能比拟的。而在整个生产流程中涉及到的数量庞大的控制回路中,相当一部分具有高度的非线性、多干扰、强耦合、大滞后等特点。尽管如此,这其中绝大部分采用的还是传统PID控制算法,或者是各个PLC制造商集成的PID功能块(例如西门子的FB41、42等)。FB42是西门子Step 7编程平台中集成的非连续PID功能块,主要用于以电动阀为代表的数字量控制回路。数字量控制回路,就是一类执行机构仅接受数字量控制信号的特殊回路。这类回路在制浆造纸过程中广泛存在,其显著特点就是其中的数字式执行机构,执行机构的特性也给这类回路的控制带来了新问题。本论文在简要介绍造纸流程的基础上,讨论了数字量回路在造纸过程中的使用特点,重点研究了西门子PID功能块FB42的内部构成,以及它在实际应用过程中存在的若干问题。针对这些问题,结合模糊控制理论的相关知识提出解决方案,并加以仿真验证。在此基础上,将新的控制方案编程实现并投入实际造纸过程应用。根据这条主线,本文从以下几方面展开了讨论。首先,论文论述了本课题的研究背景。介绍了制浆造纸过程的典型工艺流程,引出了数字量回路在制浆造纸过程中应用的广泛性及其研究意义。同时对回路中最常用的执行机构——电动阀的特性进行了总结,据此建立了电动阀的仿真模型,并分析了造纸工业中应用电动阀的几类典型数字量回路。在简单介绍模糊控制相关基础知识之后,对西门子功能块FB42及其内部各部分工作流程进行详细分析,通过试验和源代码的解读发现其内部的工作过程大致可以分为PID运算和脉冲输出两大块。其中,PID运算主要完成了比例和积分运算。积分参数不固定是FB42的特色之一,它与运算周期、阀门的行程时间和偏差有关。这种考更多还原

【Abstract】 Paper-making process is a very complex chemical process, whichinvolves equipment, both the quantitatively and types could not becompared with other industrial projects. And the production processesinvolves the numerous monitoring point, further more, a majority ofwhich takes on the characteristics of highly nonlinear,multi-interference, strong coupling, pure lag etc. Nevertheless, mostlyloops are controlled by the traditional or integrated PID algorithms(such as the Siemens’ FB41, FB42). Siemens Step 7 FB42 is theintegrated non-continuous PID functional modules, primarily forrepresented electric devices figured control loop, which is a special onethat the implementing agencies only accept digital signals from thecontroller transmissions in the control loop. This kind of loop is widelyused in the present paper-making process, its remarkable characteristicis the digital implementing agency, and the characteristic brings newquestion to this kind of loop.The thesis discussed the handling characteristics of the digital loopin paper-making based on the brief introduction of paper-making flow,has studied Siemens PID function block FB42 and its internalconstitution, and its certain questions in the application process. Inview of these questions, fuzzy control theory related knowledge isproposed to the solution, and performs the simulation confirmation. Inthis foundation, the new control plan is invested the actualpaper-making process through programmed. According to this masterline, this article has launched the discussion from following severalaspects.First, the dissertation elaborated the research background of thistopic, introduced the typical process of pulp & paper-making, and hasdrawn out the application widespread and research significance of thedigital loop in pulp & paper-making. Meanwhile, the characteristic ofelectric valve is summarized, which is the most commonly usedimplementing agency in control loop, then the simulation model ofelectric valve has established, and several kind of typical digital loopapplying the electric valve is analyzed in paper-making industry.After simple introduction fuzzy control elementary knowledge, thethesis analyzed the interior each part of work flow of Siemens functionblock FB42, through experimental and read the source code discoveredits internal work process approximately may divide into the PIDoperation and the pulse outputs two bulks. Among them, the PIDoperation has mainly completed the proportion and the integral action.The integral parameter unfixed is one of FB42 characteristics, which isconnected with the operation cycle, the valve travel time and the error.This kind of parameter choice process considerate loop error is withoutdoubt advantageous to balance the contradiction of system stability andresponse fast. The control signal of PID operation is not directly inputfor the digital implementing agency, therefore, transforms the PIDcontrol output through a three-step component into one or more pulsesoutputs, which is an important characteristic of distinguishing fromother PID algorithms. In these analysis results foundations, thesimulation model of Siemens PID function block has established.Second, according to the model of the electric valve and functionblock, linking the actual project application, several main questions hassummarized.In the final analysis, the reason that the digital loop existed thequestions is its non-linearity and making little of the function blockstructure. Therefore, the thesis produced the idea of revisingdynamically FB42 parameters with the loop error. In order to avoid thenegative influence which the non-linearity brings, embarked from theactual project experience, proposed the new strategy that combiningfuzzy control theory and FB42 to solve the questions.The union of fuzzy control theory and FB42 bodies in theformulation of fuzzy rules. According the analysis achievement ofexisting controller and the adjustment experience, the rules table isframed and the simulation model is established. This model and thementioned that of electric valve and function block constitutes acomplete simulation loop through the mutual signal transmission.Finally, the response curves obtained from simulating loop contrastto the one under the PID function block, the loop speed of responsechanges quickly and the adjustment cycle reduce. At the same time, thechanges of valve open degree under the two algorithms indicated thatthe valve quick moving and accurate and the switch times decreaseender the new algorithm. This simulation result confirmed the newcontrol plan indeed to be able to make up the insufficiency of the digitalloop under the PID function block controlling.Performs the new algorithm through the PLC programming in thescene digital loop to apply, the loop control effect promotion isremarkable, which further explained this plan is practical and feasible,has the widespread promotion application value.更多还原