scholarly journals An Improved Stability Criterion for Load Frequency Control of Power Systems with Time-Varying Delays

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2101
Author(s):  
Bi-Ying Chen ◽  
Xing-Chen Shangguan ◽  
Li Jin ◽  
Dan-Yun Li
Keyword(s):  
Power Systems ◽  
Stability Criterion ◽  
Frequency Control ◽  
Load Frequency Control ◽  
Linear Matrix ◽  
Time Varying ◽  
Time Varying Delay ◽  
Load Frequency ◽  
Improved Stability ◽  
The Stability

This paper aims at developing a novel stability criterion to access the influence of the time-varying delay on the stability of power systems equipped with a proportional-integral (PI)-based load frequency control (LFC). The model of the LFC scheme considering time-varying communication delays is established at first. Then, an improved stability condition related to the information of delay bounds is deduced by constructing an augmented Lyapunov–Krasovski functional and using a matrix inequality, and it is expressed as linear matrix inequalities (LMIs) for easily checking. Finally, case studies for one-area and two-area LFC systems are carried out to show the relationship between delay margins ensuring the stability and the PI gains of the LFC, and also verify the superiority of proposed stability criterion compared with the previous ones.

scholarly journals Enhanced Stability Criteria of Network-Based Load Frequency Control of Power Systems with Time-Varying Delays

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5820
Author(s):  
Wenxi Feng ◽  
Yanshan Xie ◽  
Fei Luo ◽  
Xianyong Zhang ◽  
Wenyong Duan
Keyword(s):  
Power Systems ◽  
Frequency Control ◽  
Load Frequency Control ◽  
Linear Matrix ◽  
Equivalent Transformation ◽  
Time Varying ◽  
Time Varying Delay ◽  
Load Frequency ◽  
Nonlinear Inequality ◽  
Improved Stability

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.

scholarly journals Robust H∞ Load Frequency Control of Power Systems Considering Intermittent Characteristics of Demand-Side Resources

Electronics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 593
Author(s):  
Kun Yuan ◽  
Zhetong Ding ◽  
Yaping Li ◽  
Mingyu Huang ◽  
Kaifeng Zhang
Keyword(s):  
Power Systems ◽  
Control Method ◽  
Frequency Control ◽  
Load Frequency Control ◽  
Linear Matrix ◽  
Intermittent Control ◽  
Demand Side ◽  
Load Frequency ◽  
The Stability ◽  
The Impact

Recently, demand-side resources (DSRs) have proceeded to participate in frequency control of the power systems. Compared with traditional generation-side resources, DSRs have unique intermittent characteristics. Taking aggregation of air conditions as an example, they must take a break after providing power support for a period of time considering the user comfort. This behavior, known as the intermittent characteristic, obviously affects the stability of the power systems. Therefore, this paper designs a corresponding controller for DSRs based on the intermittent control method. The designed controller is incorporated into the traditional load frequency control (LFC) system. The time delay is also considered. A rigorous stability proof and the robust H ∞ performance analysis is presented for the new LFC system. Then, the sufficient robust frequency stabilization result is presented in terms of linear matrix inequalities (LMIs). Finally, a two-area power system is provided to illustrate the obtained results. The results show that the designed intermittent controller can mitigate the impact of intermittent characteristics of DSRs.

scholarly journals Improved Stability Criteria of Static Recurrent Neural Networks with a Time-Varying Delay

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Lei Ding ◽  
Hong-Bing Zeng ◽  
Wei Wang ◽  
Fei Yu
Keyword(s):  
Neural Networks ◽  
Recurrent Neural Networks ◽  
Linear Matrix ◽  
Time Varying ◽  
Time Varying Delay ◽  
Improved Stability ◽  
The Stability ◽  
Delay Dependent ◽  
Delay Dependent Stability ◽  
Varying Delay

This paper investigates the stability of static recurrent neural networks (SRNNs) with a time-varying delay. Based on the complete delay-decomposing approach and quadratic separation framework, a novel Lyapunov-Krasovskii functional is constructed. By employing a reciprocally convex technique to consider the relationship between the time-varying delay and its varying interval, some improved delay-dependent stability conditions are presented in terms of linear matrix inequalities (LMIs). Finally, a numerical example is provided to show the merits and the effectiveness of the proposed methods.

scholarly journals Secure Load Frequency Control of Smart Grids under Deception Attack: A Piecewise Delay Approach

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2266 ◽  
Author(s):  
Fei Zhao ◽  
Jinsha Yuan ◽  
Ning Wang ◽  
Zhang Zhang ◽  
Helong Wen
Keyword(s):  
Smart Grids ◽  
Controller Design ◽  
Design Method ◽  
Frequency Control ◽  
Functional Method ◽  
Load Frequency Control ◽  
Linear Matrix ◽  
Load Frequency ◽  
The Stability

The problem of secure load frequency control of smart grids is investigated in this paper. The networked data transmission within the smart grid is corrupted by stochastic deception attacks. First, a unified Load frequency control model is constructed to account for both network-induced effects and deception attacks. Second, with the Lyapunov functional method, a piecewise delay analysis is conducted to study the stability of the established model, which is of less conservativeness. Third, based on the stability analysis, a controller design method is provided in terms of linear matrix inequalities. Finally, a case study is carried out to demonstrate the derived results.

Delay-Dependent Stability Analysis of Network-Based Load Frequency Control of One and Two Area Power System with Time-Varying Delays

2019 ◽  
Vol 18 (03) ◽  
pp. 1950007 ◽  
Author(s):  
S. Manikandan ◽  
Priyanka Kokil
Keyword(s):  
Time Delay ◽  
Stability Criterion ◽  
Frequency Control ◽  
Load Frequency Control ◽  
Time Varying ◽  
Control Center ◽  
Load Frequency ◽  
Plant Site ◽  
Delay Dependent ◽  
Delay Dependent Stability

Network-based load frequency control (LFC) requires data transmission from the plant site to the control center and control center to the plant site. Communication delays resulting from an open communication network impart time-varying nature to network delay. This time-varying delay may debase the dynamic performance or instability of the LFC systems. Stability of the LFC system is investigated by Lyapunov–Krasovskii functional (LKF) analysis and linear matrix inequalities (LMIs) techniques. In this paper, a less conservative delay-dependent stability criterion is derived for the time-delay system by proper constructing of LKF and imposing tighter bounding of integral terms on time-derivative of LKF. Delay margin is obtained by solving proposed stability criterion for a time-delay LFC system equipped with a proportional-integral controller. The adequacy of the proposed result is confirmed using simulation studies.

scholarly journals A New Method for Computing the Delay Margin for the Stability of Load Frequency Control Systems

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3460 ◽  
Author(s):  
Ashraf Khalil ◽  
Ang Swee Peng
Keyword(s):  
Time Delay ◽  
Power Systems ◽  
Control Systems ◽  
Frequency Control ◽  
Pi Controller ◽  
Load Frequency Control ◽  
New Method ◽  
Load Frequency ◽  
The Stability ◽  
Delay Margin

Open communication is an exigent need for future power systems, where time delay is unavoidable. In order to secure the stability of the grid, the frequency must remain within its limited range which is achieved through the load frequency control. Load frequency control signals are transmitted through communication networks which induce time delays that could destabilize power systems. So, in order to guarantee stability, the delay margin should be computed. In this paper, we present a new method for calculating the delay margin in load frequency control systems. The transcendental time delay characteristics equation is transformed into a frequency dependent equation. The spectral radius was used to find the frequencies at which the root crosses the imaginary axis. The crossing frequencies were determined through the sweeping test and the binary iteration algorithm. A one-area load frequency control system was chosen as a case study. The effectiveness of the proposed method was proven through comparison with the most recent published methods. The method shows its merit with less conservativeness and less computations. The impact of the proportional integral (PI) controller gains on the delay margin was investigated. It was found that increasing the PI controller gains reduces the delay margin.

scholarly journals Effect of different Communication Delay Latencies on LMI based Load Frequency Control Model

2019 ◽  
Vol 8 (11) ◽  
pp. 2325-2329
Keyword(s):  
Power System ◽  
Time Delays ◽  
Frequency Control ◽  
Load Frequency Control ◽  
Communication Delay ◽  
Linear Matrix ◽  
Nonlinear Parameters ◽  
Adverse Conditions ◽  
Load Frequency ◽  
The Stability

This paper present’s the study of Load Frequency Control (LFC) with certain nonlinear parameters at different communication delay latencies. The main aim is to maintain the stability of power system in all the adverse conditions including time delays in the network. Here, the stability of the system is demonstrated using Lyapuonav stability theorem in the presence of Delay’s and Linear Matrix Inequalities (LMI). Time delays are taken in the network. These delay latencies are linearized using the rational approximation method. Here Padé approximation is used with different time delay values. The problem is formulated using a decentralized LFC approach for a power system containing a single area. Simulation results carried out with different delay latency values integrated with the Load frequency control LMI and rigorous analysis is performed to test the robustness of the proposed strategy

scholarly journals Observer-Based Sliding Mode Load Frequency Control of Power Systems under Deception Attack

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Siwei Qiao ◽  
Xinghua Liu ◽  
Gaoxi Xiao ◽  
Shuzhi Sam Ge
Keyword(s):  
Sliding Mode Control ◽  
Power Systems ◽  
Sliding Mode ◽  
Frequency Control ◽  
State Equation ◽  
The State ◽  
Load Frequency Control ◽  
Linear Matrix ◽  
Mode Control ◽  
Load Frequency

This study investigates the observer-based sliding mode load frequency control for multiarea interconnected power systems under deception attack. By introducing the observer and combining it with the system state equation, the expression of the system error is obtained. A sliding mode surface is proposed to make sure the state of the systems to be stable. Then, the state equation of the system under sliding mode control is derived. The asymptotic stability of the whole system is proved by using the linear matrix inequality (LMI) technique and Lyapunov stability theory. Furthermore, a sliding mode control law is proposed to ensure that the attacked power system can reach a stable position. Numerical simulation results are presented to support the correctness of the results.

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