Application Of Nonlinear Optimal Control In Chemical Process CSTR

CSTR is a typical dynamic process of chemical industry. There are serious nonlinear, external interference and other phenomena in the process. These factors will not only destroy the stability of the control system, but also make the analysis and generalization of the system very difficult. With the continuous improvement of modern industry on the performance and control accuracy requirements of the system, the requirement for temperature control is constantly improve. Therefore, the study on the optimal control of CSTR system in chemical process has important theoretical and practical significance.This paper firstly introduces the research status of nonlinear system and optimal control theory. Then, the optimal control algorithm is studied for a chemical process CSTR system with a class of expression form. Including state regulator problem, output regulator problem, tracking control problem, and disturbance rejection tracking control problem. The main contents of this paper are summarized as follows:1. Introduce the basic concept of nonlinear system, include its research status and main methods, and also introduce the concept of affine nonlinear system. A typical nonlinear continuous stirred tank CSTR system is introduced in detail, then, analyzing and modeling for this kind of system. Introduce the related basic knowledge of differential geometry, and a nonlinear optimal control law design method is given based on this.2. Considering the nonlinear chemical process CSTR system, proposing the design method of the optimal state regulator based on the feedback linearization. The optimal control problem of the system is converted to the two point boundary value problem, then the optimal control law is obtained. In order to solve the engineering problem of state feedback,the state observer is constructed by using model transformation method, also the design method is provided.3. The output feedback is superior to the state feedback in physical implementation, so design the quadratic optimal output regulator for the nonlinear chemical process CSTR system. Consider the problem that the function of output feedback is not better than the function of state feedback, put forward a design method of the optimal regulator based on the dynamic compensator. By augmenting the dimension,translate the dynamic output feedback problem into state feedback problem, then solve the optimal control law.4. Consider the requirements for temperature in chemical control process, discuss the problem of optimal tracking control in view of the nonlinear chemical process CSTR system. Design the optimal tracking control law which can make the output of the system asymptotically track to the desired output based on the linearized nonlinear system, and to ensure the minimum error is a prerequisite. Check the feasibility and validity of the method by simulation calculation.5. Research the optimal disturbance rejection tracking control problem according to a class of disturbed chemical processes CSTR system model. Linearize the disturbed CSTR model by using feedback linearization method. Firstly, design a method for solving the optimal disturbance rejection tracking control law. Further, using model transformation, design the optimal disturbance rejection tracking control strategy without static difference by means of the internal model principle.The last part summarizes the main content and works of the paper, and look forward to the future study of scientific research, also indicate the direction of farther researching.