The Research Of Control Methods Of Nonlinear Cstr Systems

CSTR(Continuously Stirred Tank Reactor)is a very common reaction vessel in chemical production.It is widely used in chemical industry production and it is a device that operates a variety of complex chemical reactions.The stability and control performance of CSTR are directly related to large-scale industrial production processes.At the same time,the CSTR system has some difficulties,such as time-delay and nonlinear,which are not easy to overcome and lead to its control algorithm mostly complex and relatively with poor robustness and real-time.As a common control method,SMC(Sliding Mode Control)has been widely used in the actual industrial production.At present,there are some difficulties in SMC method,such as high dependence on system model?computational complexity?chattering problem are difficult to solve.More and more scholars and experts improve and perfect it,in order to achieve a more satisfactory and faster control method.In this paper,the LTR(Loop Trransfer Recovery)observers in the traditional SMC method are improved and designed for the CSTR system.In this background,the main work in this paper is as follows:Firstly,for the studied object-CSTR temperature control system,the paper describes its specific structure and basic working principle of the system.Other then,the mechanism model and related derivation process of the continuous stirred reactor system are given.For ease of operation and processing,this paper derives the non-dimensionalized model of the system,the simulation experiment of its stability also has carried out.Secondly,the design of CSTR control system based on ARX model algorithm-predictive control is completed.In order to realize the predictive control algorithm,the model is improved The system's steady state model,dynamic model and prediction model are set up respectively.On this basis,the ideal performance index is put forward,and the design of rolling optimization is designed to achieve the gradual optimization of the system.Simulation analysis shows that the dynamic response of signal response is good and the algorithm is advanced.Thirdly,the literature of common nonlinear algorithms which conclude the principle of SMC method and the transfer function recovery method LTR(Loop Transfer Recovery)technology are consulted and studied.Combined with the research on the related technology in the field of SMC and LTR at home and abroad,the basic overview of some of the control methods used in this paper is given,which made the paving for the subsequent CSTR model control.At last,in order to solve the problems above in the sliding mode variable structure method,this paper designs an improved control method based on SMC principle.And used the LTR structure as the state observer of the system for CSTR temperature control system model.This method solves the problems mentioned above more effectively,the designed LTR observer is completely invariant to the perturbation of the system,while effectively avoid the influence of outside interference.The simulation results prove the control results,whether it is real-time or robust,it can achieve the desired effect and the system will quickly reach steady state.Based on the results,this paper compares the results of two control methods for CSTR system,simulation demonstrates the control effect and performance of LTR control method based on sliding structure in nonlinear CSTR system,is better than predictive control methods based on ARX.It shows that this method has outstanding improvement,good recovery performance and stability.