Yazar "Naveed, Ausnain" seçeneğine göre listele

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    Damping Based Relative Stability Regions in Load Frequency Control System with Plug-in Electric Vehicles and Communication Delays
    (IEEE, 2020) Naveed, Ausnain; Sonmez, Sahin; Ayasun, Saffet
    This paper presents a damping based stability analysis of a time delayed single-area load frequency control (LFC) system with plug-in Electric Vehicles (EVs) Aggregator by employing a graphical method. The proposed technique computes all the stabilizing gain values of Proportional Integral (PI) controller of the LFC with plug-in EVs (LFC-EVs) system. The proposed method relies on identifying stability region and the stability boundary locus in the PI controller parameter plane having user defined relative stability. These damping based stability regions are obtained and the accuracy of their Complex Root Boundary (CRB) and Real Root Boundary (RRB) is validated by an independent algorithm and time-domain simulations. Moreover, a simple and effective analytical approach known as Weighted Geometrical Center (WGC) is used for tuning the stabilizing controller parameters to achieve better system performance.
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    Identification of Stability Delay Margin for Load Frequency Control System with Electric Vehicles Aggregator using Rekasius Substitution
    (IEEE, 2019) Naveed, Ausnain; Sonmez, Saliin; Ayasun, Saffet
    This paper implements a frequency-domain exact method, Rekasius substitution to determine the stability delay margin of a single-area load frequency control system (LFC) with electric vehicles (EVs) aggregator having constant communication delay. The method aims to compute all possible, purely complex roots of the characteristic equation for a finite positive time delay. The approach first transforms the characteristic polynomial of the LFC system with transcendental terms into a regular polynomial. Routh-Hurwitz Stability Criterion is then implemented to compute the purely imaginary roots with the crossing frequency and stability delay margin. For a wide range of proportional - integral (PI) controller gains, time delay values at which the LFC system with EVs aggregator is marginally stable are computed. The accuracy of stability delay margin results is verified by the time-domain simulations and by using an independent algorithm, the quasi-polynomial mapping-based root finder (QPmR).
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    Impact of Electric Vehicle Aggregator with Communication Time Delay on Stability Regions and Stability Delay Margins in Load Frequency Control System
    (IEEE-Inst Electrical Electronics Engineers Inc, 2021) Naveed, Ausnain; Sonmez, Sahin; Ayasun, Saffet
    This paper investigates the impact of electric vehicle (EV) aggregator with communication time delay on stability regions and stability delay margins of a single-area load frequency control (LFC) system. Primarily, a graphical method characterizing stability boundary locus is implemented. For a given time delay, the method computes all the stabilizing pro-portional-integral (PI) controller gains, which constitutes a stability region in the parameter space of PI controller. Secondly, in order to complement the stability regions, a frequency-domain exact method is used to calculate stability delay margins for various values of PI controller gains. The qualitative impact of EV aggregator on both stability regions and stability delay margins is thoroughly analyzed and the results are authenticated by time-domain simulations and quasi-polynomial mapping-based root finder (QPmR) algorithm.
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    Impact of electric vehicles aggregators with communication delays on stability delay margins of two-area load frequency control system
    (Sage Publications Ltd, 2021) Naveed, Ausnain; Sonmez, Sahin; Ayasun, Saffet
    This paper investigates the impact of electric vehicles (EVs) aggregator with communication time delay on stability delay margin of a two-area load frequency control (LFC) system. A frequency-domain exact method is used to calculate stability delay margins for various values of proportional-integral (PI) controller gains. The proposed method first eliminates the transcendental terms in the characteristic equation without using any approximation and then transforms the transcendental characteristic equation into a regular polynomial using a recursive approach. The key result of the elimination process is that real roots of the new polynomial correspond to imaginary roots of the transcendental characteristic equation. With the help of new polynomial, delay-dependent system stability and root tendency with respect to the time delay is determined. An analytical formula is then developed to compute delay margins in terms of system parameters. The qualitative impact of EVs aggregator on stability delay margins is thoroughly analysed and the results are verified by time domain simulations and quasi-polynomial mapping-based root finder (QPmR) algorithm.
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    Impact of load sharing schemes on the stability delay margins computed by Rekasius substitution method in load frequency control system with electric vehicles aggregator
    (Wiley, 2021) Naveed, Ausnain; Sonmez, Sahin; Ayasun, Saffet
    The impact of load sharing between the electric vehicles (EVs) aggregator and the conventional generator on stability delay margins in a two-area load frequency control (LFC) system is investigated in this work. A frequency-domain Rekasius substitution method is used to compute stability delay margins for different values of proportional-integral (PI) controller gains. The proposed method computes complex roots on the imaginary axis of the quasi-characteristic equation. The substitution first converts the quasi-characteristic equation of the LFC with EVs aggregator (LFC-EVs) system including delay-dependent exponential terms into an ordinary polynomial. Then, the Routh-Hurwitz stability method is applied to find those imaginary roots and the corresponding stability delay margins. The qualitative impact of different sharing schemes between the conventional generator and EVs aggregator and the impact of EVs gains on stability delay margins are thoroughly analyzed, and the results are validated by time domain simulations and quasi-polynomial mapping-based root finder algorithm. It is observed that for any given PI controller gains, stability delay margins decrease when the participation of EVs into the frequency regulation increases.
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    Optimization of PI Controller Gains using Genetic Algorithm for Time-Delayed Load Frequency Control Systems with Electric Vehicles Aggregator
    (IEEE, 2019) Naveed, Ausnain; Zerdali, Emrah; Sonmez, Sahin; Ayasun, Saffet
    This paper presents a genetic algorithm (GA) based approach to optimize controller gains for a single-area load frequency control system that includes an electric vehicles (EVs) aggregator and incommensurate communication time delays. Firstly, a stability boundary locus method is implemented to determine all stabilizing proportional integral (PI) controller gain that constitutes a stability region in the controller parameter space. A GA based optimization approach is then utilized to obtain an optimum set of controller gain that minimizes the mean square error of the deviation in the system frequency response. The effectiveness of the controller in retaining the desired frequency response is validated by time domain-simulation.
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    Stability Regions in the Parameter Space of PI Controller for LFC System with EVs Aggregator and Incommensurate Time Delays
    (IEEE, 2019) Naveed, Ausnain; Sonmez, Sahin; Ayasun, Saffet
    This paper presents a graphical method to compute all stabilizing Proportional Integral (PI) controller gains of a single-area Load Frequency Control (LFC) system with Electric Vehicles (EVs) Aggregator and multiple incommensurate communication time delays. The proposed approach is based on extracting stability region and the stability boundary locus in the PI controller parameter space. For various values of communication time delays, stability regions are obtained and the accuracy of Complex Root Boundary (CRB) and Real Root Boundary (RRB) are verified by means of quasi-polynomial mapping-based root finder (QPmR) algorithm and time-domain simulations.
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    The effect of demand response control on stability delay margins of load frequency control systems with communication time-delays
    (Tubitak Scientific & Technological Research Council Turkey, 2021) Katipoglu, Deniz; Sonmez, Sahin; Ayasun, Saffet; Naveed, Ausnain
    This paper studies the effect of dynamic demand response (DR) control on stability delay margins of load frequency control (LFC) systems including communication time-delays. A DR control loop is included in each control area, called as LFC-DR system and Rekasius substitution is utilized to identify stability margins for various proportional integral (PI) gains and participation ratios of the secondary and DR control loops. The purpose of Rekasius substitution technique is to obtain purely complex roots on the imaginary axis of the time-delayed LFC-DR system. This substitution first converts the characteristic equation of the LFC-DR system including delay-dependent exponential terms into an ordinary polynomial. Then the well-known Routh-Hurwitz stability method is applied to find those imaginary roots and the corresponding stability delay margin known as maximal time-delay. Delay margin results indicate that the inclusion of DR control loop significantly increases stability delay margin and improves the frequency dynamic behavior of the LFC system including time-delays. Theoretical stability margins are confirmed by a proven algorithm, quasi-polynomial mapping-based root finder (QPmR) algorithm and time-domain simulations.