SYNTHESIS OF A BOILER STEAM PRESSURE ROBUST CONTROL SYSTEM USING THE INTERVAL SYSTEMS FAMILY EXTENDED ROOT LOCUS

Abstract

A vast class of industrial control systems should be properly controlled in conditions of substantial plant uncertainties and external perturbations. Robust control synthesis methods such as H∞ optimization, LMI approach are not efficient if a plant model order is not defined. For this reason, the aim of this paper is to recommend a technique for robust control implementation based on interval polynomial generation. The polynomials roots location theory permits to generate an interval polynomial providing the roots location in a dedicated area on the complex plane when a plant is subject to uncertainty. The limits of such an area are selected in order to minimize the negative effect of disturbances and to provide appropriate quality of system dynamics. The polynomials order is defined by controller order. Thus, for the second order PID-controller parameterization the second order is assumed for a plant model. Hence, the polynomial order is four. The robust PID-controller parameterization is achieved for a boiler steam pressure control. The simulation results are presented for this system which demonstrate quality of system dynamics improvement in conditions of parametric and external perturbations.