Synthesis of the cascade control system of the thermal regime of a technological object by the methods of synergetic control theory

Abstract

The paper considers technological control objects whose physical properties, state of aggregation and composition are changed by hydromechanical, physical and chemical effects on the flows of initial substances. The main feature of such objects is their multi-dimensionality, nonlinearity, multiconnectivity, and parametric uncertainty of the mathematical model at the design stage. One of such objects is the chemical reactor with the thermal regime predominantly controlled by single-loop or cascade automatic control systems based on linear algorithms. The main disadvantage of such systems is the problem of maintaining robustness, i.e. stability and control quality under the action of parametric disturbances. In our opinion, the method of analytical design of aggregated regulators (ADAR), developed within the framework of the synergetic control theory, is promising in this sense. The research uses methods of system analysis of technological processes as control objects, methods of the automatic control theory and analytical synthesis of control algorithms based on the synergetic control theory and computer simulation methods. Using the ADAR method, we have solved the problem of algorithmic synthesis of the cascade-coupled control system of the thermal regime of a technological object (chemical reactor) in the nonlinear formulation applying a nonlinear mathematical model of the object. Computer simulation methods have proved the functionality of the «object – control subsystem» complex: system stability, covariance with the set point. It is shown that in the systems controlling thermal processes of the considered type, the heat transfer coefficient parametric uncertainty can lead to an excessive value of the static error, which means that the algorithmic structure of the automatic control system has to be improved. To ensure full robustness of the automatic control system, it is recommended to make the system’s algorithmic structure more complex by introducing an astatic component into the control law and correcting the algorithm tuning parameters.