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    Öğe
    Identification of gain and phase margins based robust stability regions for a time-delayed micro-grid system including fractional-order controller in presence of renewable power generation
    (Tubitak Scientific & Technological Research Council Turkey, 2022) Gunduz, Hakan; Sonmez, Sahin; Ayasun, Saffet
    This study examines the gain and phase margins (GPMs) based robust stability margins in the parameter space of fractional order proportional-integral (FOPI) controller for a micro-grid (MG) system with communication time delays. Fluctuations in renewable energy sources (RESs), uncertainties in parameters of system components and communication delays could adversely affect the dynamical analysis and frequency stability of the MG system. Such a MG system has an interval characteristic due to the parametric variations and the interval transfer functions defined by Kharitonov's theorem, which presents a solution for checking of robust stability. Therefore, this study addresses the robust stability regions containing a set of robust FOPI controller gains for all possible transfer functions of the MG system by a simple graphical method working in controller parameter space. In this way, the impact of fractional order degree of integral controller on the robust stability regions is exhaustively examined by the graphical method. Additionally, robust performance of the interval MG system in terms of design specifications including GPMs is analyzed, and the effect of GPMs on the robust regions is investigated by the graphical method. Results indicate that GPM parameters provide the desirable performances for the MG and fractional order of integral controller considerably increases the robustness of the stability margin of the MG when compared with the integer order PI controller.
  • [ X ]
    Öğe
    Tuning of Controller Parameters for Time-Delayed Micro-Grid System Including Electric Vehicle
    (Ieee, 2020) Gunduz, Hakan; Sonmez, Sahin; Ayasun, Saffet
    This paper presents the design of proportional-integral (PI) controller parameters of a communication time-delayed micro-grid (MG) system with electric vehicle (EV) via a simple analytical approach known as Weighted Geometrical Center (WGC). This method aims to calculate the WGC point of the stability regions obtained by stability boundary locus method in PI controller parameters space. The WGC points of the stability regions for the time-delayed MG ensure a good dynamic performance. Therefore, the study investigates the system frequency responses for WGC points of computed stability regions for different participation factors of EVs and time delay values. The performance of designed controller parameters by WGC method is compared with Ziegler-Nichols (Z-N) based controller parameters.