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    Öğe
    A Novel Parameter Identification Method for Single-Phase Transformers by Using Real-Time Data
    (Ieee-Inst Electrical Electronics Engineers Inc, 2014) Dirik, Hasan; Gezegin, Cenk; Ozdemir, Muammer
    Equivalent circuit parameters of transformers are related to the condition of their windings. Information concerning winding deformations, failures, and temperature can be acquired by monitoring these parameters. Methods used for the determination of electrical parameters generally require disconnection of the transformer from the power system. In this paper, a novel method which uses real-time data of the transformer to determine its parameters is presented. Therefore, this method eliminates the need for the disconnection of the transformer from the power system. In the method, winding parameters are obtained by applying the differential equation algorithm to the fundamental frequency components of transformer data. Fundamental frequency components of the currents and voltages are computed by using the discrete cosine transform. Transformer core parameters are also computed via core losses and the polynomial curve-fitting method with the least squares error method. The proposed method has been tested and validated by simulations and experiments.
  • [ X ]
    Öğe
    New extraction method for active, reactive and individual harmonic components from distorted current signal
    (Inst Engineering Technology-Iet, 2014) Dirik, Hasan; Ozdemir, Muammer
    Quality problems encountered in power systems usually originate from reactive and harmonic current components drawn by non-linear loads. Therefore the extraction of reactive and harmonic current components from distorted current waveform is a vital issue in the works aiming to monitor and eliminate power quality problems. In this study, a new method that provides the extraction of active, reactive and harmonic current components from distorted current is presented. The method has been based on the differential equation of the single-phase source-load system. The proposed method performs computations by using a sliding sampling window that has a width of half of the fundamental cycle. Immunity to noise, being less affected from frequency deviations and being not influenced from dc component that may exist in load currents are some other advantages of the proposed method. The method has been analysed and compared to two commonly used methods, namely discrete Fourier transform (DFT) and dq, by using a series of simulations that have been executed in Matlab/Simulink environment. Simulation results demonstrated the effectiveness of the proposed method.