Jana Závacká

Robust stabilization of a chemical reactor

Robust static output feedback control was applied to a continuous stirred tank reactor with parametric uncertainty and multiple steady states in which exothermic reaction takes place. The problem of robust controller design was converted to a solution of linear matrix inequalities and a computationally simple non-iterative algorithm is presented. The possibility of using robust static output feedback for stabilization of reactors with uncertainty and comparison of robust P and PI controllers with an optimal controller is demonstrated by simulation results.

The Kronecker summation method for robust stabilization applied to a chemical reactor

The paper focuses on robust stabilization where the suitable parameters of a simple continuous-time PI controller are determined through a combination of the Kronecker summation method, sixteen plant theorem, and an algebraic approach to control design in the ring of proper and stable rational functions. The initial theoretical background is followed by an illustrative experiment which includes computation of the controller and verification of control results for a continuous stirred tank reactor with exothermic reaction modelled as a fourth-order interval system.

Design of Robust PI Controller for Counter-Current Tubular Heat Exchangers

Abstract The paper presents an approach for robust PI controller design for a system affected by parametric uncertainty. The method is based on plotting the stability boundary locus in the plane of controller parameters that is called (kp, ki)-plane. Designed robust PI controller is implemented for control of two counter-current tubular heat exchangers in series with uncertain parameters, in which kerosene as a product of distillation in a refinery has to be cooled by water. The controlled variable is the temperature of the outlet stream of the kerosene from the second heat exchanger and the control input is the volumetric flow rate of the inlet stream of the cold water in the second heat exchanger. Simulation results of robust PI control of heat exchangers are also presented.

Robust PI controller design for a laboratory time delay process

The paper presents an approach to robust PI controller design for systems with interval parametric uncertainty and time delay. It is supposed that the controlled system is described by a transfer function with parameters lying in certain intervals and with a time delay term. The transfer function of the controlled system is modified by approximation of the time delay term by its Pade expansion. The area of all PI controller parameters kp, ki, that are able to assure the robust stability of the feedback closed loop, is found by the method, which is based on plotting the stability boundary locus in the (kp, ki)-plane. Then the pole-placement method is used to specify those controller parameters from the robust stability area, which assure quality of the control performance prescribed by a choice of closed loop poles or relative damping or natural undamped frequency of the control response. The contribution presents theoretical results confirmed by practical experiments in laboratory conditions. Robust PI controllers are found using designed approach for control of an electronic equipment with varying time delay. Designed robust PI controllers are realized using the PLC SIMATIC S7–300.

Robust PI controller design for a continuous stirred tank reactor with multiple steady-states

The paper presents a method for robust PI controller design for a system affected by parametric uncertainty. The proposed method is based on plotting the stability boundary locus in the plane of controller parameters that is called (kp, ki)-plane. The design approach is verified using simulations of robust stabilization and control of the chemical continuous-time stirred tank reactor (CSTR) with hydrolysis of propylene glycol. The control input is the volumetric flow rate of the reaction mixture and the controlled output is the temperature of the reacting mixture. The reactor which has three uncertain parameters is controlled into its stable and unstable steady-state. Obtained results confirm that designed robust PI controllers ensure robust stability in both steady-states.