Research Of Modeling And Optimization Control In Polypropylene Production Process

Polypropylene (PP) is one of the backbone industry of our country, and it is of great significance to promote, as soon as possible, the production technique level of the PP. the large size PP devices as a complex large scale engineering systems exhibit various characteristics, such as the nonlinearity, uncertainties, large time delays, strong coupling, distributed parameters, and hybrid properties. Therefore, it is of great practical significance to implement the optimal operation, advanced control and the optimal grade transition strategy for the PP production process, and thus to realize the energy consumption reduction and the multi- grade production for the PP production.This thesis focuses on the modeling and control of the CSTR plant. The CSTR plant is modeled as a nonlinear time-delay system, then, the fuzzy control, model predictive control, and other advanced control strategy are applied to investigate the optimization control problem of the obtained nonlinear time-delay system. The main research work and the achievements of the thesis are listed as follows:1. Based on the careful study of the results in the existing literature, the knowledge about the PP are systematically introduced, and the most recent advance of the research work on the system modeling and identification of the PP production process, optimization control are also introduced.2. The modeling problem is studied for the CSTR plant. The dynamic model of the production process is established based on the analysis of the mechanism and the dynamical characteristics of the PP. and establish the nonlinear time-delay system model of the CSTR plant.3. Based on the obtained nonlinear time-delay system model, the T-S fuzzy model approach is used to deal with the nonlinear problem in the system model, moreover, combined with the guaranteed cost control method, a fuzzy guaranteed cost controller with less conservatism is designed for the obtain system model.4. Based on the obtained nonlinear time-delay system model, the delay-dependent analysis and synthesis method for time-delay systems is proposed to deal with the time delay problem in the system model. Furthermore, a new delay-dependent fuzzy model predictive controller design method is presented based on the proposed delay-dependent method incorporated with the fuzzy model predictive control approach. The proposed controller design method effectively solves the nonlinear problem in the established system model and is of less conservative.5. Finally, the conclusions are presented, and the work needs further investigation are remarked.