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    An application of different approaches to missing data for electric load forecasting by using an advanced gene expression programming algorithm
    (Nova Science Publishers, Inc., 2021) Zor, Kasim; Çelik, Özgür
    More recently, electric load forecasting has become a crucial tool in planning and management of modern electric power systems owing to the fact that it provides insights acquired by employing data analytics along with artificial intelligence for the forthcoming internet of energy era. The ubiquity of missing data is frequently encountered in the load forecasting applications and several imputation approaches have been carried out in the literature. Meanwhile, the use of artificial intelligence-based techniques is required to deal with the nonlinear nature of electric loads which is originated from seasonal and other effects. Furthermore, gene expression programming is one of the proven artificial intelligence-based techniques which produces simple equations between explanatory variables and target variable. In this study, an application of different approaches to missing data for short-term electric load forecasting by using an advanced gene expression programming algorithm is comprehensively introduced through a case study. Consequently, impacts of each imputation approach and the advanced gene expression programming algorithm on forecasting process are discussed, and the results of the study are presented in details. © 2021 by Nova Science Publishers, Inc. All rights reserved.
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    An efficient control scheme for operational performance enhancement of vehicular fuel cell integrated power system
    (Elsevier B.V., 2025) Çelik, Özgür
    Recent advancements in fuel cell (FC) technology have positioned it as a promising alternative energy source across various stationary, mobile, and transportation applications. As fuel cell vehicles (FCVs) become increasingly prominent in the transportation sector, they also offer the potential to function as supplementary stationary energy providers when parked, thereby contributing to the grid. In this study, a control method to enhance the energy transfer capability of an FCV-integrated grid system is proposed. To manage energy transfer between grid and FCVs, classical strategies using fixed parameter controllers suffer from performance degradation due to the nonlinear and external parameter-dependent nature of the FC stacks. The proposed adaptive fractional-order proportional-integral strategy bears the advantage of self-tuning parameters feature for designing the control parameters of power conditioning unit. Using fractional-order control endows the system with memory and heredity, enhancing its ability to handle nonlinearity and uncertainty. Through case studies, it is demonstrated that the proposed strategy reduces vehicular FC output power variations by over 60 % while enhancing transient response by 50 % compared to classical control methods. Thus, the limitations such as low control flexibility, slow transient response, and high undershoot/overshoot rates addressed by the classical controllers are countered thanks to the developed strategy. © 2024 Elsevier B.V.
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    Analysis of Current Limiting Algorithm with Anti-Windup Control for Transient Stability of Grid-Forming Converters
    (2023) Çelik, Özgür
    In modern power grids, renewable energy sources (RESs) are integrated to the grid through voltage source converters (VSCs) with grid-forming capabilities. Grid forming VSCs’ weak overcurrent capability revealed the need for current limiting techniques under large disturbances like short-circuit faults. However, current saturation algorithms induce transient instabilities due to the AC voltage controller windup issue when the current is saturated. Therefore, analyzing the transient stability of the grid-forming units in case of fault conditions is crucial for ensuring the reliable and secure operation of the grid. This paper investigates the effects of the current limiting algorithm with anti-windup control to handle transient instabilities during fault conditions. An elaborated theoretical analysis of the presented system is performed by considering different case studies. The simulations are conducted by using Matlab/Simulink software to test the validity of the presented system. The obtained results highlight the advantages of an anti-windup controller during current saturation mode.
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    Design and analysis of two-stage bidirectional power converter for vehicle-to-grid technology with fuel cell-battery electric vehicle
    (Elsevier Ltd, 2025) Ekici, Elanur; Koroglu, Tahsin; Çelik, Özgür
    This paper presents the design and analysis of an isolated bidirectional two-stage power converter for vehicle-to-grid (V2G) technology with a fuel cell (FC) battery electric vehicle (FCBEV). In the first stage, the primary side employs a quadratic boost converter to achieve higher voltage levels, while the secondary side uses a voltage balancer circuit to equalize the DC subgrid terminal voltages. In the second stage, a T-type inverter is used for grid connection, effectively minimizing total harmonic distortion (THD). An Artificial Neural Network (ANN)-based maximum power point tracking technique combined with a Genetic Algorithm (GA) has been used to extract the maximum energy from the FC under changing temperature and pressure conditions in the system. The performance of the proposed converter has been evaluated and validated through simulation studies using MATLAB/Simulink software. The results demonstrate that the performance of the proposed converter is satisfactory under varying operating conditions. The grid current THD is maintained below 2.35 % in accordance with IEEE 519 standards. The proposed converter and control strategy facilitate the integration of EVs with renewable energy sources and bipolar hybrid AC/DC microgrids. © 2024 Elsevier Ltd
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    ENHANCEMENT OF A LOW-COST INTELLIGENT DEVICE FOR IMPROVING ENERGY EFFICIENCY IN BUILDINGS
    (2018) Timur, Oğuzhan; Teke, Ahmet; Zor, Kasım; Çelik, Özgür
    Ascending energy demand and vanishing nonrenewable energyresources have increased the prominence of energy efficiency nowadays. In orderto accomplish an energy efficient future for the forthcoming generations ofhumanity, traditional devices possessing low efficiency should be altered withintelligent devices having high efficiency. Thanks to internet of things (IoT),conventional devices have been turned into intelligent devices which can beremotely accessed, monitored and controlled by utilizing ubiquitous sensormechanisms. In this study, enhancement of a low-cost intelligent device (iDev) istargeted to develop in order to compute and store electrical energy consumptioninto a database by an embedded card named as Arduino which has the capabilityof measuring voltage, current, frequency and power factor for improving energyefficiency in buildings. When a classic device is connected to the enhanced iDev,the device is converted to an intelligent device that is remotely controllable. As aconsequence, if a whole building is equipped with the proposed iDev, it isconsidered that a large amount of electrical energy will be saved for a better andlivable Earth.
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    Survey of Photovoltaic (PV) Technologies, PV Module Characteristics, Connection Forms and Standards
    (2015) Çelik, Özgür; Teke, Ahmet; Yıldırım, H. Başak
    Son yıllarda enerjinin etkin kullanımı, nüfus artışı ve sanayileşme ile birlikte hızla artan enerji talebine bağlı olarak çok önemli hale getirmiştir. Enerji kullanımında artan talebe paralel olarak dünya geneli enerji arzı çok büyük baskıya maruz kalmaktadır. Bu nedenle enerji verimliliği ve alternatif enerji kaynaklarının kullanılması çok önemli bir konu haline gelmiştir. Fotovoltaik sistemler (FV) en çok kullanılan alternatif enerji kaynakları arasında gösterilebilir ve bu teknoloji gün geçtikçe dikkat çekici popülerlik kazanmaktadır. Fakat, FV sistemler düşük verimlilik, yüksek kurulum maliyeti ve değişken atmosferik koşullardan negatif olarak etkilenmektedirler. Son zamanlarda çalışmalar kullanılan hammaddeleri modifiye ederek FV panellerin yapısal verimliliğini artırmak ve enerji verimliliği çözümleri sağlamak amacıyla genişletilmiştir. Bu yazıda FV hücre teknolojisi üzerine kullanılanhammadeler baz alınarak verimlilik, fiyat ve teknik özellikler açısından inceleme yapılması amaçlanmıştır. Öte yandan panel karakteristiği çıkarımı ve güç sistemlerinin benzetiminde kullanmak için PSCAD/EMTDC programı kullanılarak FV panel modeli sunulmuştur. Bu panel modeli hem şebeke bağlantılı FV sistemlerin hemde şebekeden bağımsız sistemlerin güç sistem dinamiği ve geçici durum analizi çıkarımı için uygundur. Ayrıca Türkiye için şebekeye bağlantı şartları ve baz alınan şartnamelerin detaylı incelenmesi.