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    A Demand Side Management Controller Configuration for Interleaved DC-DC Converters Applicable for Renewable Energy Sources
    (Wiley, 2021) Ertekin, Davut; Bayrak, Gökay; Subramaniam, Umashankar
    In Micro-grid applications, accuracy and sensitivity of the Demand Side Management (DSM) process decrease when the load impedance changes. In this study, the impact of the DSM is analyzed and the interleaved structure is presented for DC-DC converter blocks equipped with adaptive PI controllers. This approach reinforces a same voltage source that can be a serial and parallel connection of Photovoltaic (PV) panels in different power rates as the input voltage source to enhance the voltage to the micro-grid DC level and is modeling the power transmission in Renewable Energy Sources (RESs) that they produce limited amounts of power. For the voltage droop problem, the Power-Voltage (P-V) approach is selected. Since the resistive loads are considered in this study, this approach can control DC currents based and depending on the DC voltages in DC micro-grid applications. For per controller block, different values of the gain coefficients are tested and the optimal droop coefficients are presented. All simulations have been done in MATLAB/SIMULINK and a prototype by power around 1kW is tested. The results of the hardware implementation confirm the theoretical and simulation outcomes.
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    An Efficient Full-wave and Switched-capacitor-based AC-DC-DC Converter Configuration; Applicable for High Voltage Gain Industrial Utilizations
    (Institute of Electrical and Electronics Engineers Inc., 2021) Ertekin, Davut; Bilgiç, Mesut Berke; Mutlu, Bülent
    Power electronics circuits are one of the vital and important parts of the industrial applications, where different levels of the DC and AC voltages and currents are necessary to be applied to the different electronic and electrical devices and machines including the test approaches or working under industrial voltages. Meanwhile, many of these devices are designed to work under a certain and fixed industrial level of voltages like 48VDC, 24VDC, 12VDC or 5VDC, but sometimes, another levels of the voltage for a special device can be an issue. Therefore, the converting an AC voltage to a fixed, controllable and robust DC voltage under different level of the load values is necessary. Furthermore, the variation of the input AC voltage also should be considered and the load DC voltages should be hold fixed. This paper uses a Full-wave rectifier circuit to convert the AC voltage to the DC voltage and in the next step this voltage is enhanced and fixed by using a DC-DC step-up converter. Both rectifier and boost converters are high gain since sometimes it is necessary to convert the grid 220VAC to a small DC voltage or enhance a small DC to a higher DC voltage. The proposed converter can be used separately as a high gain AC-DC rectifier or a high gain DC-DC converter, or the combination of the proposed converters can be used to reach a desired DC voltage through an input AC voltage. It can be considered depending on the area where the converter is used. Theoretical analysis is presented and simulation results confirm the correctness of the topology under different working conditions.
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    An improved automated PQD classification method for distributed generators with hybrid SVM-based approach using un-decimated wavelet transform
    (Elsevier, 2021) Yılmaz, Alper; Kucuker, Ahmet; Bayrak, Gökay; Ertekin, Davut; Shafie-Khah, Miadreza; Guerrero, Josep M.
    Artificial intelligence (AI) approaches are usually coupled with the wavelet transform (WT) for feature extraction to classify the power quality disturbances (PQDs). Therefore, selecting a useful WT-based signal processing approach is required for a reliable classification, especially in real-time applications. In this study, a new hybrid, un-decimated wavelet-transform (UWT)-based feature extraction method using a support vector machine (SVM) with a "' a trous" algorithm is proposed to classify PQDs in distributed generators (DGs). The proposed method was performed in a real-time application of a DG system to classify PQDs. The derived features were tested on five different machine learning (ML) models by determining the most appropriate classification technique for the proposed UWT-based feature extraction method. An experimental DG system is constituted in the laboratory using a LabVIEW environment, and the proposed method is tested under different grid conditions. Besides, other well-known and studied conventional ML methods were also tested under 25 dB, 30 dB, and 40 dB noise and compared to the developed method. The experimental and simulation results show that the features extracted with the proposed UWT-based method provide much more successful results in classification than the existing wavelet methods in the literature. Furthermore, the proposed method's noise sensitivity performance is much better than other conventional wavelet algorithms, especially in real-time applications.
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    A novel switched-capacitor and fuzzy logic-based quadratic boost converter with mitigated voltage stress, applicable for DC micro-grid
    (Springer, 2022) Tekin, Hakan; Bulut, Kübra; Ertekin, Davut
    High-voltage and efficient power converter topologies equipped with the simple and practical controller circuits are necessary, especially for integration between the low-power and low-voltage renewable energy sources (RESs) like the photovoltaic (PV) arrays and the grid. These converters can be used widely in electrical vehicles (EVs) or charging stations, aquatic, medical, transportation application and other cases. This study proposes a switched capacitor (SC)-based quadratic boost converter (QBC) structure that provides high-voltage gain at low duty cycles equipped with the fuzzy logic control (FLC) technique. The output gain of the proposed converter is higher than a second-order step-up converter or a conventional QB circuit thanks to the presented switched-capacitor topology and the manipulation of the switches in conventional QBC. By using the second switch to the conventional QBC, the voltage stress across the main power switch will decrease that enhance the reliability and long-life of the converter. Since the SC block acts as an intermediate layer between the QB and load through the capacitors and diodes of this block, the voltage and current stresses of the power switches and diodes on the QB side are less than stresses for semiconductors for classical QB and boost converter. In this study, the proposed QBC and controller system are analyzed mathematically in detail and in MATLAB/SIMULINK environment. A 200 W prototype was developed in the laboratory to validate the proposed converter and computerized analysis. Finally, the theoretical and experimental results were compared and verified.
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    A real-time energy management system design for a developed pv-based distributed generator considering the grid code requirements in Turkey
    (MDPI, 2021) Bayrak, Gökay; Ertekin, Davut; Alhelou H.H.; Siano P.
    Each country must determine the Grid Code conditions and apply these criteria to integrate distributed generation (DG) systems into the existing electricity grid and to ensure a stable power system. Thus, experimental studies are required to provide an effective, national, and specific Grid Code. In this study, the Turkish Grid Code’s electrical criteria were examined, and the application of these criteria was carried out on a developed PV-based DG. A real-time energy management system (RTEMS) was proposed in the study. Electrical parameters on the developed DG were monitored in real-time by considering IEEE 1547, IEEE 929–2000, and Turkey’s electrical criteria. A practical grid code study was firstly investigated in detail about the Turkish Grid Code by a developed real-time monitoring-control and protection system. The proposed RTEMS method in the study is implemented as an inverter-resident system; thus, it provides advantages over many energy management systems embedded in the inverter. The degradation in power quality and non-detection zone (NDZ) problems encountered in active and passive island mode detection methods developed embedded in the inverter are eliminated in the proposed method. With the RTEMS method, where under and over-voltage, under and over voltage frequency, and unintentional island mode events can be detected in real-time, both the existing grid-code requirements are met, and the existing power quality and NDZ problem is eliminated with the recommended inverter-independent RTEMS method.