【作者】 郑春燕；

【导师】 麻红昭；

【作者基本信息】 浙江大学 ， 化学工程， 2004， 硕士

【摘要】 中和过程是一个典型的非线性、纯时延过程，用常规的线性控制方法不可能对其进行有效控制。在对中和过程自动控制算法的探索中，采用了非线性增益补偿控制和前馈控制，由于中和控制过程的反应过程变化复杂，模型难以确定，因此基于模型的前馈控制无法对pH值和流量值的波动进行有效的补偿。常规PID控制算法也无法对反应的变化过程做快速的、精确的反应，在控制过程中很容易引起振荡现象，很难对系统实现最优控制。 对此，本文提出了用一种基于模糊神经网络MRAC控制方案来实现中和过程的优化控制。模糊神经网络是用神经元网络来构造模糊系统，其即具有模糊系统善于表达人的经验性知识，又具有神经元网络的根据输入输出样本来自动设计和调整模糊系统的设计参数，实现模糊系统的自学习和自适应功能的特性。基于模糊神经网络的自适应控制方案可以在线学习和调整规则参数及隶属函数参数，其控制规则表是根据现场实际控制数据并通过计算得出的，再将之应用于现场的控制中，具有很高的适应性，并保证闭环控制系统的稳定性，有高度鲁棒性，适用于非线性、时变、时滞系统的控制。因此，模糊神经网络控制的应用能很好的克服这种缺陷，适合于中和过程的非线性变化过程。 本文的研究工作主要包括以下内容： (1)综述了智能控制的研究发展，介绍了模糊控制技术和神经网络控制技术的各自优缺点，以及神经网络控制器的典型结构和几种常用的神经网络，自适应控制的特点及其应用。 (2)分析了中和过程控制的非线性时延特性和控制难度。介绍在实际应用中一般采用的控制方法：非线性增益补偿PID控制和前馈控制及其控制的效果，分析了存在的问题和困难。 (3)根据模糊系统和神经网络的优缺点，提出了用神经网络来构造模糊系统，一个基于模糊神经网络控制算法。设计了模糊神经网络控制器，以及把基于模糊神经网络的自适应控制应用到中和过程，建模并仿真。 (4)提出了基于PLC的pH中和过程自动控制系统，并把基于模糊神经网络自适应控制算法应用到某电化厂的pH中和过程自动控制系统中，最后分析了基于模糊神经网络自适应控制算法在中和过程的应用结果，以及PLC在pH中和自摘要动控制系统中的应用结果。本文最后对全文所做的工作进行了总结，并提出了今后进一步研究所需要做的工作。更多还原

【Abstract】 Neutralization process is a typical nonlinear process with pure time delay. This process can’t be controlled effectively with conventional linear control method. Feed back control base on Nonlinear PID with self-adjust parameter and feed forward control base on experience model are employed in the practical application. The realization of this control system and its result are introduced in this paper. Because the process of the reaction is complicated, it’s difficult to model for it. The Nonlinear PID can’t fit the change of the reaction. The feed forward control base on model also can’t fit the change of pH value and flux of the original water. So the control method can’t get a good result.In terms of the above considerations, this thesis proposes a new nonlinear adaptive control method based on fuzzy neural network to realize optimization control of pH neutralization process. Fuzzy neural network not only has the characteristic of fuzzy system, but also has the characteristic of neural network. The nonlinear adaptive control method based on fuzzy neural network can learn and adjust rule parameter and subjection parameter on line. And the control rule list is calculated according to control data on the spot, which is also applied to the control on the spot. Therefore, it has good adaptive and robust and also can ensure the stability of closed loop control system, which is fit to handle both the nonlinearities and time-varying characteristics of the pH process.The research work of this thesis consists of the following major parts:Firstly, this thesis summarizes the development of intelligent control and also introduces the advantage and disadvantage of fuzzy control technique and neural control technique respectively. The characteristic and application of adaptive control are also presented in this thesis.Secondly, the traditional control for pH process ?the compensation of nonlinearities plus PID control is presented in this thesis.Thirdly, the fuzzy neural network controller is designed and the adaptive control method based on fuzzy neural network is proposed according to the advantage and disadvantage of fuzzy system and neural network in this thesis. And the adaptive control method based on fuzzy neural network is applied to pH process.Forth, Aimed at the process of pH value control of wastewater treatment in chemical factory, a PLC-based automatic control system of pH value of wastewater treatment is developed. In this thesis operation principle of this system, hardware configuration, and software configuration are all discussed in detail.At last, a summary of the paper is given and further research interests are also proposed.更多还原