中文论文文摘

    纸浆浓度是造纸过程中最重要的物理量之一。纸浆浓度——尤其是上网浓度即文中提到的抄前池出口浓度——对纸张的定量高低起着决定性的影响。正是因为纸浆浓度如此重要，所以在制浆造纸DCS系统中，对浓度回路的控制要求较之其它类型的回路都要高。
    当前造纸行业浓度控制普遍采用传统PID算法，PID算法具有结构简单、实现方便、适应性强等特点，但是其在浓度回路中的应用存在下面几点问题：①调节缓慢；②抗干扰能力弱；③稳定性差等。同造纸生产线上其他控制回路相比，传统PID控制下的浓度回路在改变设定值后，测量值稳定到新设定值上的时间是最长的。同时，车速的提高、浆泵转速的改变、原浆浓度的波动等干扰产生时，浓度回路很容易偏离设定值发生较大幅度的波动。这些问题的存在限制了纸浆浓度控制精度的提高，更成为纸张质量的进一步提升的一个瓶颈。
本论文结合白板纸制浆线，详细分析了浓度调节工艺。经过分析发现：PID算法在浓度控制中的若干问题归根到底是孤立了同一制浆线上多段浓度控制回路之间的联系所致。
    基于这个理解，文章提出了一个新的浓度控制指导思想，即把同一制浆线上的多段浓度控制回路视为一个整体，并按照控制精度的高低来划分各个回路在浓度控制大系统中的作用和地位。本论文就白板纸芯层制浆线三个浓度控制回路之间的相互关系展开了分析，按照这个分析结果，文章提出了各个回路之间的关系模型，并对其进行了简要验证。
    处理多段浓度控制回路构成的大系统，在控制算法的选取上，如何避免没有详细准确系统数学模型的不足就成了主要的依据。正因如此，本文提出了基于专家控制思想的纸浆浓度控制新思路。
    专家控制在纸浆浓度调节系统中的应用，既考虑到了和PID算法的结合，又根据多个回路之间的关系起到了回路与回路之间的协调作用。在与PID的结合上，专家控制器着重处理一些意外情况，尽管对于PID控制参数的调整也有所涉及，但其根本目的还是要让控制回路尽可能摆脱意外情况对控制品质的影响。单回路中专家控制器就是在归纳了现场操作人员在意外情况发生时采取措施的有效经验的基础上，把这些经验用专家规则的形式表述出来并依此形成专家控制器。多回路之间的专家控制器中的控制规则主要是依据回路与回路之间关系以及在某个回路发生大幅度的波动时应该采取的措施来制定的。
    建立好的专家控制器结合回路其他部件模型在Matlab下进行仿真，其仿真结果曲线充分证明了专家PID较之传统PID在提高系统响应速度、增强抗干扰能力等特性上有优势。
    新的控制方案结合西门子PLC平台进行了编程实现，并在杭州富阳某白板纸生产线进行了现场测试运行，其实时控制曲线如仿真曲线一样再次证明了本论文提出的新算法是切实可行的，提高浓度控制效果明显，在实际应用中有着广泛的推广价值。

外文论文文摘

    The Pulp consistency is one of the most important physical measurements. The consistency, especially the consistency before the headbox, determined the paper quality. So important the pulp consistency is, the acquirement of consistency control system is more strict then the other system in the DCS.
    PID algorithm is used widely in the consistency control system, and the PID algorithm has some advanced feature, such as the simple construct, the easy realization, and the good adaptive. However, it produced some disadvantage by used in the consistency control. Slow responsibility, bad anti-disturbance and steady is the major thing. Contract with the other circle in the pulp-making process, when the set-point is changed, the adjust time of consistency is the longest one. At the same time, the change of pulp-motor’s speed and shake of pulp’s consistency may move the consistency out of the set-point. All of the troubles pull down improvement of the consistency control, and limited the advance of paper quality.
    This paper combined with the pulp-making process, analysis the consistency control process. After the analysis, it is found that the disadvantage of the consistency control is made by the isolation of many of the consistency control circle.
    Based on this understanding, this article raised a new guiding ideology for the consistency control, what combined many of consistency circles in the same line as a whole, and distributed the role in the large systems in accordance with the control precision.
This paper analysis the interrelationship in the three consistency circuits in the Xin layer pulp. In accordance with the results of analysis, the article put forwards the relationship model, and done some certification about it.
    Handling the large system that is composed of many consistency circuits, the main basis in the control algorithm selection is how to avoid the lack of detailed accurate mathematical model of system. For this reason, this paper raised a new idea to pulp consistency control based on the expert control.
    The application of expert control, is taken into account the PID algorithms, and coordinated the relation between the circuits. In combination with the PID, the expert controller focused on a number of contingencies. Although the PID control parameters are involved, but the fundamental purpose is to get the control circuits away the bad effects on control quality.
Expert controller in the single circuit is based on the experience, which is summarized from the effective measures when the accidents happened, and recorded in the form of expert rule. The control rules in the multi-circuits are based on the relationship between the circuits in the large system, and the measures to deal with the fluctuations in some consistency circuit.
    Expert controller simulate in the Matlab with the other part model in control circuit. The result curve of simulation proved that the expert PID has more advantage than the traditional PID in increasing response speed, enhancing the anti-interference capabilities and so on.
The new control program was realized in the Siemens PLC platform, and taken into operation in a paper-making line in Fuyang. As same as the simulation results, the fact runtime trend curve proved that the new algorithm is practical; the effect in improving the control performance is obvious. So the application of expert control in the pulp consistency has an extensive space to popularize.