Yazar "El-Sheikhi, Farag Ali" seçeneğine göre listele

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    Ellipsoidal-Set Design of the Decentralized Plug and Play Control for Direct Current Microgrids
    (Ieee-Inst Electrical Electronics Engineers Inc, 2021) Soliman, Hisham M.; Bayoumi, Ehab H. E.; El-Sheikhi, Farag Ali; Ibrahim, Amr M.
    Recently the integration of renewable energy resources to direct-current microgrids has become a hot research topic. The voltage stability problem is of paramount importance when the system is subject to external disturbances, parameters uncertainties, and plug-and-play regimes. This paper introduces a novel decentralized voltage tracking for a direct-current islanded microgrid. It consists of numerous Distributed Generation units. The decentralized controller of each distributed generator adjusts the voltage at the point of common coupling to track the desired reference. The proposed control copes with the plug-and-play operation of the microgrid. This means that the possibility of connection/disconnection distributed generators without deteriorating the stability of the overall microgrid is done through the invariant ellipsoid set and the linear matrix inequality optimization. Another merit of the proposed control is that updating the rest of the controllers is not required when a distributed generator is plugged in or out. Moreover, the proposed decentralized controller just uses local states (information) of its distributed generator only. Many simulations and practical studies with different scenarios have been conducted in this paper to verify the performance of the proposed controllers. Comparison with the existing schemes is included.
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    Grid frequency stabilisation under magnitude and generation rate constraints
    (Inderscience Enterprises Ltd, 2024) Soliman, Hisham M.; Benzaouia, Abdellah; El-Sheikhi, Farag Ali; Buyukatak, Kenan
    A new load frequency control (LFC) design in a multi-area power system is introduced in this paper. The proposed design tackles the problem of constraints on both control magnitude and its rate. With this design, the control limits (corresponding to a fully open/closed fuel valve) are not violated. Also, the generation rate constraint (GRC) is kept within the permissible range imposed in practice. Violation of such constraints may lead to instability or damage of mechanical parts. A pole placement method is used to solve this inverse problem. The resulting stabiliser is state feedback plus integral control. The proposed control avoids the complexity in modelling the nonlinear like of the GRC. Unlike other designs, the suggested control represents a link between the pole placement procedure and these constraints. To validate the efficacy of the proposed design, digital simulations for single and two-area power systems are presented in this paper. A comparison is made between the proposed control and the traditional control scheme which confirms the proposed technique's supremacy.
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    Invariant Set-Based DC Microgrid Decentralized Actuator Fault-Tolerant Control
    (Ieee-Inst Electrical Electronics Engineers Inc, 2023) Soliman, Hisham M.; Bayoumi, Ehab H. E.; El-Sheikhi, Farag Ali; Ahshan, Razzaqul; Nengroo, Sarvar Hussain; Lee, Sangkeum
    Faults and system failure components are primarily two causes of unstable or deteriorating control performance of power system. In this study, we present a novel approach to the decentralized restoration of large DC microgrids using fault-tolerant control (FTC). The microgrid achieves decentralization by partitioning into several smaller grids. Each independent grid views the actions of the other grids as an external disturbance. The malfunction of the controller is represented in the input matrix as a norm-bounded uncertainty. The disturbance impact is diminished due to the proposed invariant-set approach. The proposed control can address simultaneous failures in actuators with random placement and degradation levels. In a passive FTC system, when the defect cannot be detected (or the fault may not have been clearly addressed), the proposed technique is utilized. After the fault has occurred, it can be viewed as an uncertainty in system dynamics. The controller that stabilizes the system is obtained by solving iteratively bilinear matrix inequalities as linear matrix inequalities. In addition, this study presents and discusses positive outcomes of applying this method to a system of six interconnected DC microgrids in the event of multiple fault types. The proposed control successfully stabilizes the severe case of simultaneous actuator faults.
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    Regional Pole Placers of Power Systems under Random Failures/Repair Markov Jumps
    (MDPI, 2021) El-Sheikhi, Farag Ali; Soliman, Hisham M.; Ahshan, Razzaqul; Hossain, Eklas
    This paper deals with a discrete-time stochastic control model design for random failure prone and maintenance in a single machine infinite bus (SMIB) system. This model includes the practical values of failure/repair rate of transmission lines and transformers. The probability matrix is, therefore, calculated accordingly. The model considers two extreme modes of operations: the most reliable mode and the least reliable contingency case. This allows the control design which stochastically stabilizes the system under jump Markov disturbances. For adequate transient response, the proposed state feedback power system stabilizer (PSS) achieves a desired settling time and damping ratio by placing the closed-loop poles in a desired region. The control target should also be satisfied for load variations in either mode of operation. A sufficient condition is developed to achieve the control objectives via solving a set of linear matrix inequalities (LMI). Using simulation, the performance of the designed controller is tested for the system that prone to random failure/maintenance under various loading conditions. Simulation results reveal that the closed-loop poles reside within the desired region satisfying the required settling time and damping ratio under the aforementioned disturbances. The contributions of the paper are summarized as follows: (1) modeling of transition probability matrix under Markov Jumps using practical data, (2) designing a controller by compelling the closed poles into the desired region to achieve adequate dynamic performance under different load varying conditions.
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    Robust decentralized plug and play voltage tracker of islanded microgrids under loads and lines uncertainties by the invariant ellipsoids
    (King Saud University, 2024) Bayoumi, Ehab H.E.; Soliman, Hisham M.; El-Sheikhi, Farag Ali; Shafiq, M.; Awad, Hilmy
    Microgrids (MGs) comprising of distributed generation units (DGs) are subjected to plug-and-play operation (PnP), lines (connecting the DGs) parameters uncertainty, and load changes. Robust stability and an authentic operation for islanded microgrids can be guaranteed through a robust decentralized voltage tracker developed in this paper. The proposed controller design has the following merits: 1) fully decentralized, 2) scalable, and 3) maintains robust stability against PnP of DGs, load changes, and lines parameters’ uncertainties. A sufficient condition is developed by linear matrix inequality convex optimization is exploited to solve the problem. The MGs’ changes in load and the line's parameters are modelled as norm-bounded uncertainties. The suggested controller uses local measurements from DGs, i.e., decentralized by the decomposition of the global system into subsystems. For each subsystem, the rest of the system's impact is considered disturbances, whose influence must be minimized. The proposed disturbance rejection control algorithm is based on the method of invariant-ellipsoids. Several time-domain scenarios such as connecting and disconnecting a number of DGs, local load changes, and variation of transmission line parameters are executed to assess the suggested controller's effectiveness, using MATLAB /Sim PowerSystems Toolbox. © 2021 The Authors