Yazar "Ahshan, Razzaqul" seçeneğine göre listele

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  • [ X ]
    Öğe
    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.
  • [ X ]
    Öğe
    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.