Stability analysis of load frequency control for power systems with interval time-varying delays

Abstract

This study investigates the stability problem of load frequency control (LFC) for power systems with interval time-varying delays. The two categories of time delays, the lower bound being zero and non-zero, are considered. The systems can be described as time delay systems of load disturbances. First, an augmented Lyapunov–Krasovskii functional (LKF) is constructed. Some delay-dependent nonintegral terms and single integral terms are additionally introduced to make full use of the information on the system state variables and the time-varying delays. Second, to overcome the problem of nonlinear inequalities caused by the augmented LKF, the nonlinear inequalities are converted into linear matrix inequalities (LMIs) by applying the new negative definite inequality equivalence transformation lemma, which can be solved easily by the MATLAB LMI toolbox. A new stability criterion is presented by applying the Lyapunov stability theory. The stability criterion is less conservative than some existing literature studies, which further improves the stability margin for the power systems based on LFC. Finally, some numerical examples are given to show the effectiveness of the proposed method and the superiority of the results.

Advanced Protection for the Smart Grid

“…Hence, the system needs a control strategy for regulation. As the core application of automatic power generation OPEN ACCESS EDITED BY Srete Nikolovski, Josip Juraj Strossmayer University of Osijek, Croatia control in power systems, load frequency control (LFC) is also an essential tool for dealing with grid frequency matters resulting from load changes (Zhao et al, 2022;Sun et al, 2023). LFC mainly adjusts the grid frequency deviation and the exchange power value of the contact line to make the system frequency reach the rated value, while maintaining the tie-lines exchanged power at the normal value (Yang et al, 2020).…”

Stability Analysis of Two-Area LFC Power Systems With Two Additive Interval Time-Varying Delays

“…PI control has good robustness and independent on the exact model of the power system, which is widely used in the industrial field at present. To solve the stability problem of LFC power systems with time-varying delay based on PI controllers, a large number of scholars have given good results [7,[34][35][36][37][38]. However, these results only consider the case where the lower bound of the time-varying delay is zero.…”