Abstract
The stability problem for load frequency control (LFC) of power systems with two time-varying communication delays is studied in this paper. The one-area and two-area LFC systems are considered, respectively, which are modeled as corresponding linear systems with additive time-varying delays. An improved stability criterion is proposed via a modified Lyapunov-Krasovskii functional (LKF) approach. Firstly, an augmented LKF consisting of delay-dependent matrices and some single-integral items containing time-varying delay information in two different delay subintervals is constructed, which makes full use of the coupling information between the system states and time-varying delays. Secondly, the novel negative definite inequality equivalent transformation lemma is used to transform the nonlinear inequality to the linear matrix inequality (LMI) equivalently, which can be easily solved by the MATLAB LMI-Toolbox. Finally, some numerical examples are presented to show the improvement of the proposed approach.
Highlights
To overcome the nonlinear matrix inequality in the stability criterion, the novel negative definite inequality equivalent transformation lemma proposed in [39] is used to transform the nonlinear inequality to the LMI equivalently, which can be solved by the MATLAB LMI-Toolbox
To overcome the nonlinear matrix inequality in the stability criterion, the novel negative definite inequality equivalent transformation lemma (Lemma 3) proposed in [39] is used to transform the inequality (A8) to the LMI (12) equivalently, which can be solved by the MATLAB LMI-Toolbox
This paper mainly focuses on the stability analysis for load frequency control of power systems with time-varying delays
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. On the other hand, the communication time-varying delays from the control center to the governor and from the sensor to the LFC center are considered simultaneously [19,20,21], where general delay-dependent stability analysis is studied by using additive time-varying delays to model two different time delays arising in communication channels. In order to reduce the conservativeness of the LKF construction, a lot of coupling information between the system state variables and time delays is introduced into the LKF, which leads to some nonlinear terms in the final results. The stability problem for LFC power systems with two time-varying communication delays is studied. Both one-area and two-area LFC systems are considered, respectively. A B symmetric matrices A and C of appropriate dimensions, denotes a real symmetric
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