Computation of parametric uncertainty margin using stability boundary locus: An application to load frequency control

Abstract

In this paper, computation of parametric uncertainty margin (PUM) of a system is explored. In the presence of parametric uncertainty, maintaining the stability of the system is a daunting task. In view of this, in this paper, a new methodology is proposed to determine the maximum parametric uncertainty or PUM that can be tolerated in an interval type proportional–integral (PI) controlled system so that the whole system remains robustly stable. In order to show the validity of the proposed approach, an example of interval type load frequency control (LFC) system is considered to determine the PUM numerically. The proposed approach utilizes the concept of Kharitonov’s theorem for the modeling of interval type systems and stability boundary locus (SBL) technique for the designing of PI controller. The PUM obtained using the proposed approach is compared by that achieved by Kharitonov’s rectangles and zero exclusion principle.