Delay-Dependent Stability Analysis of the Power System With a Wide-Area Damping Controller Embedded

This paper investigates the delay-dependent stability of a power system equipped with a wide-area damping controller (WADC) using a new method which consists of a delay-dependent criterion based on Lyapunov theory and model reduction technique. The delay margin, the maximal delay which allows the closed-loop power system to retain stable, is calculated based on the reduced order model and linear matrix inequality (LMI) technique. Both constant and time-varying delays introduced by the transmission of the remote signals are investigated. Cases studies are carried out based on a two-area four-machine power system controlled by a conventional lead-lag WADC and a robust WADC. The relationship between the parameters of WADC and the delay margin has been investigated and is used to guide the design of WADC and achieve a trade-off between the damping performance and delay margin. The effectiveness of the proposed method is verified by simulation studies.