Research On Robust Control Technology Of Chemical Reactor System Based On Backstepping Control Approach

Continuous Stirred Tank Reactor(CSTR)is a kind of complex chemical reactor which has many advantages compared with other reactors,such as the low investment cost.In addition,CSTR is capable of effective heat exchange and can adjust the temperature in time during the reaction process,so as to improve the reaction rate and yield.Meanwhile,the continuous process is used so that CSTR can easier operation and produce high quality products stably.Therefore,it has been extensively used in petrochemical,biological fermentation,chemical pharmaceutical and other process industries.However,Only by accurately controlling the temperature and concentration of the reactor can the CSTR operate stably.For example,the temperature of the reactor must be strictly controlled when performing a specific chemical reaction to make sure that the reactants can fully react and produce stable products.The concentration changes of the reactants can be quickly monitored by collecting samples from the reactor in a timely manner.In this way,the reaction conditions can be adjusted and optimized in time to improve production efficiency and assure product quality.In actual industrial production,reactor equipment often exists in the form of interconnection.Multiple reactor equipment in parallel can carry out multiple reactions at the same time,which can improve production efficiency,and avoid problems with a reactor that affect the entire production line during the reaction just because of equipment problems effectively.The series connection of multiple reactor equipment can divide a reaction process into multiple steps,and each step will process the reaction product,so that the conversion rate of the product is greatly improved.In addition,the tandem connection of multiple reactor equipment can also add some special processing steps during the reaction,such as heating,cooling,dilution,etc.,so that the reaction can be more precisely controlled and thus more ideal reaction products can be obtained.In view of this situation,a kind of two stage CSTR model consisting of two CSTRs connected in series is established is established based on a single reactor,and the controller design is studied by backstepping control technology.First of all,a backstepping tracking control scheme based on disturbance observer is proposed for a kind of two stage CSTR system with unknown external disturbance and system uncertainty.According to the actual reaction process of CSTR,a strict feedback nonlinear system model is established,and the unknown external disturbance and system uncertainty in the system reaction process are regarded as composite disturbance,a nonlinear interference observer is designed to estimate the composite disturbance,and the output of disturbance observer is used for the controller design.Then,by using the backstepping control technique,a robust control scheme of a kind of two stage CSTR system is designed,so that the system actually outputs the expected reference signal on tracking,and analyzes the bounded stability of the closed-loop system signal through Lyapunov stability theory.Finally,Simulink is used to carry out numerical simulation experiments on the system to verify the effectiveness of the proposed tracking control scheme.Secondly,for a kind of two stage CSTR system with unknown external disturbance and system uncertainty,a fixed-time tracking control scheme with constrained output is proposed based on backstepping control technology,Radial Basis Function(RBF)neural network and disturbance observer.According to the actual reaction process of a kind of two stage CSTR system,a strict feedback nonlinear system model is established,a fixed-time disturbance observer is designed to estimate the unknown disturbance in the reaction process,and the disturbance observer output is used for the controller design.Then,by introducing an error transfer function,the tracking error is kept within a predetermined range.By using the backstepping technique,a fixed-time control scheme based on RBF neural network is designed to ensure that the system output can track the desired signal at a fixed time,and also ensure that the output error of the system converges to a given range and all signals in the closed-loop system are bounded.Finally,numerical simulation experiments are carried out on the two stage CSTR system,which verifies the effectiveness of the designed scheme.