Browsing by Author "Alisar, Ibrahim"

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    Citation - Scopus: 1
    Flexible Reactive Power Capacity of Full Converter Wind Turbines
    (Institute of Electrical and Electronics Engineers Inc., 2021) Alisar I.; Demirok, Erhan; Alisar, Ibrahim
    This study proposes a control system for parallel connected back-to-back converters of FC (full converter) wind turbines in order to increase the total reactive power capacity. A sample wind turbine was chosen to use the power curve and different wind profiles. Various grid voltage values have been utilized to examine the effectiveness of the proposed method. The enhancement of reactive power capacity has been showed for each wind speed and each collector grid voltage level with the proposed method. The increase of reactive power capability of the sample wind turbine was obtained and demonstrated using MATLAB. © 2021 Chamber of Turkish Electrical Engineers.
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    A System Level Lifetime Enhancement Method for Power Converters of Type-4 Wind Turbines
    (IEEE, 2024) Alisar, Ibrahim; Demirok, Erhan; Akan, Aydin
    This study proposes a new system level lifetime enhancement method for back-to-back connected power converters of Type-4 wind turbines. The method is based on swapping both the position and roles of MSC (machine side converter) and GSC (grid side converter) periodically at ultra low frequency with additional mechanical switches so that the lifetime consumption of electrical switches (IGBTs and diodes) is shared by the inverter and rectifier operating modes. Moreover, the aging effect of the semiconductors have been considered and tested as an additional evaluation. The proposed method is tested with PSCAD (for the simulation of wind turbine and converter system) and MATLAB (for the development of thermal models, loss calculation and lifetime calculations) tools. The results show the effectiveness of the proposed method with significantly increased lifetime values.