Research On Robust Control Strategies Of Continuously Stirred Tank Reactor

Continuously Stirred Tank Reactor-CSTR is widely used as chemical reactors in the industrial fields of ferment, chemical industry, petrolic manufacture, biologic pharmacy and so on. The benefit and the quality standard of production will be deeply affected by the control impact. In order to ensure the well-balanced chemical process, we can control the stability of the inner parameter as temperature, pressure, consistence, etc. The nonlinear dynamic equation of CSTR can be built on the basis of materiel equivalency by the mechanism modeling method. In the practical industry possesses, most of the systems are uncertain nonlinear system. The uncertainty appears as parameter incertitude, model error and the unknown disturbance. The robust stability of the system is an important standard to appraise the control effect of the system which presents uncertainty. The purpose of robust control is to design a controller which can make sure the system achieve the anticipant guide line when the system exists the effect of uncertainty. One of the control tasks of CSTR is tracking control. That is to say, we design a controller to ensure the practical output to track the enacting output.Aimed at the uncertainty which exists in the CSTR nonlinear system, this paper designs certain robust tracking controllers and analyses another tracking controller. The paper also analyses the robust tracking characteristics of stability when the CSTR system applies different designed ways of controllers in order to assure the CSTR system with uncertain disturbance to achieve the optimal control purpose.The accomplished work has been done as follows:1. The paper analyses the nonlinear dynamic equation of CSTR which has been build on the basis of materiel equivalency by the mechanism modeling method.2. The paper linearizes the nonlinear dynamic model of CSTR as input-output linearization, now we obtain the linearizing system of CSTR. During the linearizing process, we can calculate the CSTR's inner dynamic sub-system and obtain a steadily zero-dynamic sub-system. We design a nonlinear VSC for the CSTR and do the stimulant work. Aimed at the chattering effect with the nonlinear system, we adopt an improving method to design the original controller. The simulate results indicate that the output track and the error tracking curve doesn't appear the overshoot and go to the stability quickly when there exists the disturbance of the invariable-oriented disturbance, exponential decay-oriented disturbance, sine periodicity-orienteddisturbance in the CSTR. So the VSC of CSTR has nicer robust stability.3 . The paper analyses the nonlinear increment-oriented predictive tracking controller for the CSTR. The simulate work has been done in the paper. The simulate results indicate that the tracking error appears overshoot and the velocity going to the stability is slower than the VSC if the CSTR system exists the invariable-oriented disturbance, exponential decay-oriented disturbance, sine periodicity-oriented disturbance, etc. Another disadvantage of this controller is the bigger fluctuant amplitude.