Delay-dependent stability analysis for load frequency control systems with two delay components

This paper investigates the delay-dependent stability of the LFC scheme considering two time-varying delays, a new less conservative delay-dependent stability criterion is proposed to study the delay margin of LFC system with PI controller based on Lyapunov-Krasovskii (LK) functional method and linear matrix inequality (LMI) technique. In the presented stability analysis procedure, the time derivative of the LK functional is bounded tightly using the Jesen inequality and the extended reciprocally convex matrix inequality. The proposed stability criterion is tested on the one-area and multi-area LFC systems, and the delay margins with respect to different value of gains of PI controllers are computed to investigate the quantitative effect of the controller gains on the delay margin, and are obtained for different load disturbance to discuss the effect of the exogenous load disturbance.