【作者】 沈玉玲；

【导师】 李少远； 蔡文剑；

【作者基本信息】 上海交通大学 ， 控制理论与控制工程， 2012， 博士

【摘要】 由于大多数的工业过程都可以描述成多变量系统,因此,多变量控制系统一直是工业过程控制领域中的研究热点之一。工业过程中常用的控制策略,比如分散PI/PID控制和解耦控制,都因为其便利的现场调试操控性而得到了广泛的应用。对于耦合不严重的多变量系统,在合理配对的前提下,分散控制就可以得到满意的控制性能。而对于耦合严重的多变量系统,解耦控制策略则更加适合。如何真正有效地解除多变量回路之间的耦合作用,将复杂的多变量控制问题转换成简单的单变量控制问题,一直是工程师和学者们思索的焦点。本文在等价传递函数理论的基础上,结合经典单变量PID控制技术,对多变量控制系统进行深入分析,并进行多变量控制系统设计研究,大量的数学仿真和实验结果表明本论文提出的方法是简单有效的,在工业过程领域具有很好的应用前景。本论文的主要内容包括:1)系统阐述了多变量系统等价传递函数的概念、含义和性质,以及等价传递函数模型的参数化方法,在此基础上提出一种基于特性序列的等价传递函数的参数化方法,定义了特性序列来描述过程的动态特性,推导出了开环的特性序列和等价传递函数的特性序列之间的关系,并根据特性序列和模型参数之间的对应关系建立方程组,可以求解出等价传递函数的模型参数。另外,本文还给出了几类特殊的多变量过程的等价传递函数模型参数化方法。2)提出基于等价传递函数的多变量系统集中式PI/PID控制器设计。集中式多变量控制器结构中的每个PI/PID控制器元素都是分开独立地针对每一个等价传递函数描述的单变量过程设计,可以保证在满足各个单变量控制目标的同时满足整个多变量系统的控制目标。因此,与分散式PI/PID控制器相比,集中式PI/PID控制器可以提供更好的总体控制性能。3)提出基于等价传递函数矩阵的多变量系统解耦控制器设计方法。根据控制器结构的不同,又分为两种:一种是一体式或全矩阵结构的解耦控制器,解耦控制器由闭环期望传递函数矩阵和等价传递函数矩阵综合推导得到;另外一种是分体式的解耦控制器,由解耦器和PI/PID控制器两部分组成。首先,利用等价传递函数矩阵和传递函数逆阵之间的关系,选择合理的解耦后的前向通道的期望传递函数矩阵,可以直接推导出解耦控制器的解析形式。接着,运用经典的单回路PI/PID控制器设计方法,针对开环期望传递函数矩阵的元素分别设计PI/PID控制器,组成多变量系统的分散控制器。4)提出基于等价传递函数矩阵的多变量系统部分解耦控制器设计方法,该方法和解耦控制器设计方法的不同点主要在于,解耦器结构的不同。部分解耦器主要考虑在控制性能和控制结构的复杂程度之间的折衷,引入了结构选择标准,在不影响控制性能的前提下尽可能地简化解耦器的结构。另外,该方法还分析了等价传递函数矩阵和传递函数逆阵之间的近似等价关系对总体控制性能可能带来的消极影响,为了避免这种影响,引入了对等价传递函数模型参数的约束,从而保证了等价传递函数的合理性。5)针对提出的两种解耦控制器的设计方法,分别设计了两个仿真平台验证实验:双容液位控制实验和中央空调恒温控制实验。无论数学仿真还是实物仿真结果,均验证了基于ETF的解耦控制器设计方法的有效性。更多还原

【Abstract】 As most of the industrial processes can be described as multivariable systems, the research of multivariable control systems is one of the hotspots in industrial process control area. The two commonly used strategies are decentralized control and decoupling control, which are easy to operate on the spot and easy to understand by the local engineers. As for the processes with slight coupling, decentralized control is competent to get satisfactory control results after the optimal paring solution is selected. Decoupling control mehod is more perferable to the decentralized control for the processes with serious coupling. How to handle the interactions among loops is always a headache question for the control engineers. In this thesis, several effective multivarible control strategies are proposed, which is based on the ETF therories and classical PID control technique. It includes:1) The concept of equivalent transfer function for multivarible processes is introduced. Furthermore, the important property of ETF and its parameterization methods are also presented. A brand-new approach for high-order ETF model parameterization is involved, which is based on the open-loop charateristic sequence. The relationship between the open-loop charateristic sequence and charateristic sequence of the ETF matrix is derived. The parameters of ETF models are uniquely determined by solving the equation sets about the charateristic sequence. In addition, the parameteriazation methods for some special multivariable processes are also involved.2) A ETF based centralized PI/PID controller design method for multivariable processes is presented, in which each element of the controller is designed individualy for corresponding ETF element. The control target of multivariable process can be attained simultaneously when the control targets of the single variable processes are achieved. Thus, centralized PI/PID controller can provide better overall control performance , particularly compared to the decentralized PI/PID controller.3) A systematic ETF based decoupling control scheme is brought up, which can be divided into one-piece type and split type according to the different control structure.The one-piece decoupling controller can be derived by the desired closed-loop transfer fucntion matrix and the ETF matrix, while the split one is composed of two parts: the decoupler and multiloop PI/PID controller. By using the approximation relationship between ETF matrix and the inverse matrix and selecting the desirable forward transfer function matrix after decoupled, the decoulper will be derived directly. After that, the decentralized PI/PID controller is easily designed for the desirable transfer function matrix by available single loop controller design methods.4) A novel ETF based partial decoupling control strategy is raised. The obvious difference from the former one is the structure of decoupler. By measuring the effect of each ETF element in decoupling control, a partial decoupling control structure selection criterion is proposed with the aim for the decoupler to have least complexity and satisfied overall system performance. Besides, the possible negative effect caused by the approximation between ETF matrix and the inverse matrix is also considered. To gurantee the reasonability, the ETF parameters are obtained under certain constraints.5) Two experimental tests are designed to verify the effectiveness of ETF based decoupling control methods. The controlled plants are respectively double-level control system and 4-room constant temperature control system. The results of both mathematical simulation and the experimental test demonstrate that the ETF based decoupling control strategies are simple and effective.更多还原