【作者】 汤琴；

【导师】 杨辉；

【作者基本信息】 华东交通大学 ， 电力系统及其自动化， 2009， 硕士

【摘要】 醋酸乙烯聚合率是聚乙烯醇生产过程中重要的质量参数,它对生产过程的安全性、经济性和产品品质具有重要影响,但它目前主要靠人工采样离线检测、操作人员依据生产经验进行调控。本文对醋酸乙烯聚合率的在线检测和优化控制进行了探索性研究,主要探讨了两个方面的问题:采用软测量技术实现聚合率的在线估计以及采用预测控制的方法对聚合率进行控制。本文所做的具体研究如下:1、在了解醋酸乙烯聚合过程工艺机理基础之上,分析了影响醋酸乙烯聚合率的因素,采用了RBF神经网络、最小二乘支持向量机、增量最小二乘支持向量机三种方法建立醋酸乙烯聚合率软测量模型,并利用工业现场的实际测量数据对这几种方法进行了仿真研究和比较。仿真结果表明,增量最小二乘支持向量机方法能根据误差要求调整训练目标,所建模型表现出很高的拟合精度和预测精度,泛化能力强,而且具有在线学习功能,比较适合用于醋酸乙烯聚合率的在线估计。2、针对聚合反应过程具有非线性、时变、有噪声干扰和和滞后等特点,常规控制方法很难得到令人满意的效果,将预测控制中的隐式广义预测控制算法应用到聚合率控制中。这类算法对模型的精度要求不高,另外,由于在优化中引入了多步预测思想,使其抗扰动及时延变化等能力显著提高。因此本文采用了该算法进行醋酸乙烯聚合率控制系统的设计,并用MATLAB对该算法进行了仿真研究。仿真结果表明该隐式广义预测算法动态响应快,跟踪效果好,能够获得较好的控制效果,并通过仿真分析了隐式广义预测控制中的主要参数对系统性能的影响。研究结果对醋酸乙烯聚合率在线测量和优化控制具有重要意义。更多还原

【Abstract】 The vinyl acetate(VAC) polymerization rate is an important quality parameters in the process of the Poly Vinyl Alcohol production, it has significant influence on security, economy of production process and product quality. At present, it mainly relies on manual sampling off-line detection and is controlled by the operators’experiences. This paper mainly studies two problems: on-line estimation of VAC polymerization rate by using soft-sensing technique and optimizing control of VAC polymerization rate by using the method of predictive control. The concrete research works are as follows:1. On the basis of comprehension of VAC polymerization process mechanics, various factors which affect VAC polymerization rate are analyzed and the soft-sensing model of VAC polymerization rate is established by using three methods including RBF neural network, Least Squares Support Vector Machine(LS-SVM) and Incremental Least Squares Support Vector Machines (ILS-SVM). Then the simulation based on the practical industrial data is researched and compared. The simulation results show that ILS-SVM can adjust training aims according to the error requirement and possesses high fitting and prediction precision, it has good abilities of generalization and the function of studying on line and is fit for on-line estimation of VAC polymerization rate.2. The process of VAC polymerization has the characteristics such as nonlinearity, time-varying, disturbance and time-delay, the traditional control strategy can’t acquire satisfactory result, so the implicit generalized predictive control(GPC) algorithm is applied in the control of polymerization rate. This algorithm doesn’t depend on exact model, and its ability of disturbance rejection and time-varying restraining has been enhanced greatly with the multi-step forecasting concept. So, the implicit GPC algorithm is adopted to design for the control system of VAC polymerization rate and simulation research is done with MATLAB. The simulation results show that the implicit GPC algorithm can obtain good control performance in both the dynamic response and tracking performance. Finally, the influence of main parameters of the implicit GPC algorithm is analyzed through simulation.Results shows that it is of importance to online prediction and optimizing control of VAC polymerization rate.更多还原