Browsing by Author "Meral, M. Emin"

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Active Power Filter: Review of Converter Topologies and Control Strategies
(Gazi Univ, 2011) Teke, Ahmet; Saribulut, Lutfu; Meral, M. Emin; Tumay, Mehmet
Decrease in the cost of power electronic devices and improvement in the efficiency of both power converters and energy storage components have increased the applicability of new technological solutions such as Custom Power (CP) and Flexible AC Transmission Systems (FACTS) Devices. Active Power Filter (APF) is one of the CP devices and can mitigate harmonics, reactive power and unbalanced load currents originating from load side. In this study, a comprehensive review of APF studies, the advantages and disadvantages of each presented techniques are presented. The study also helps the researchers to select the optimum control strategies and power circuit configuration for APF applications.
Benchmarking Simulation and Theory of Various Plls Produce Orthogonal Signals Under Abnormal Electric Grid Conditions
(Springer, 2018) Meral, M. Emin; Celik, Dogan
The voltage or current harmonics and unbalancing have severe influence on control of various applications such as power quality devices, distributed generation systems, power converter devices, electric vehicle chargers and electric motors. Orthogonal d-q signals are significantly a part of controller for these applications. This paper proposes a new synchronization method based on integration average filter (AF) into conventional phase locked loop (PLL) in order to attenuate negative effect of voltage harmonics and unbalanced on orthogonal d-q signals for controller. Although some advanced techniques in the literature ensure good performances, uses of multiple filters reduce dynamic response and suffer from computational burden. The proposed improved AF-PLL has simple structure and implementation. It provides fast phase detection, fast dynamic response and removes ripple errors of voltage unbalance and harmonics. The performance of the filter-based PLL is evaluated in terms of balanced, unbalanced condition and harmonics distortion. The effectiveness and reliability of the proposed AF-PLL are demonstrated and discussed by means of comparative conventional PLL and advanced PLL in the literature. PSCAD/EMTDC is used for simulation and examination of all PLLs.
Comparison of Srf/Pi- and Strf/Pr-based Power Controllers for Grid-Tied Distributed Generation Systems
(Springer, 2018) Meral, M. Emin; Celik, Dogan
Grid-tied distributed generation (DG) system-based renewable energy sources such as wind, sun and hydrogen have recently gained a large attention due mainly to environmental issues. In this study, to provide energy for various loads, it is connected to the common direct current bus system after DG system-based fuel cell and solar cell are modeled and simulated. In order to synchronize DG system sources to utility grid, park transformation-based three-phase phase-locked loop technique is used, which is one of the most common methods in the literature. Power control method-based synchronous reference frame with proportional integral controller or stationary reference frame with proportional resonant current controller is used in the DG systems. The performances of two controllers are discussed in this study. Simulation results are obtained for various scenarios at the designed and created simulation model of DG + Grid + Load system. The system is modeled and simulated by using PSCAD/EMTDC software package.
Computer Simulation and Experimental Implementation of a Pic-Controlled Hybrid Multilevel Inverter for Undergraduate Laboratories
(Wiley, 2012) Saribulut, Lutfu; Teke, Ahmet; Meral, M. Emin; Tumay, Mehmet
Hybrid multilevel inverters have emerged as attractive power conversion systems at medium voltage levels, which are structured by cascaded series inverters having different internal DC bus voltages. This scheme therefore provides the capability to produce higher voltages at higher speeds with low switching losses and high conversion efficiency. The fundamentals and importance of hybrid multilevel systems can be easily enhanced by the undergraduate with visual learning and laboratory studies. However, the students cannot be able to implement the peripheral interface controller (PIC)-based projects sufficiently. In this paper, the simulation models and experimental setup of a hybrid multilevel inverter are presented in detail. From the theoretical and experimental experience obtained from this study, the students and engineers can provide more analytical opportunities for studying control algorithms of PIC controlled power electronics projects. This will provide the students to reinforce their lectures and laboratory studies. (c) 2010 Wiley Periodicals, Inc. Comput Appl Eng Educ 20: 445453, 2012
Implementation of a Non-Linear Adaptive Filter Based Sag Detection Method for Dynamic Voltage Restorers Under Unbalanced Fault Conditions
(Springer Heidelberg, 2013) Cuma, M. Ugras; Teke, Ahmet; Meral, M. Emin; Bayindir, K. Cagatay; Tumay, Mehmet
The most common power quality problems in distribution systems are related to unbalanced voltage sags. Voltage sags must be detected quickly and corrected in a minimum amount of time. One of the most widely used methods for sag detection is based on the d-q transformation. This method has the disadvantage of missing the detection of unbalanced faults, because this method uses a voltage sag level signal obtained from the average of 3 phases for sag detection. In this paper, an adaptive filter sag detection method is proposed for Dynamic Voltage Restorers (DVR) under unbalanced fault conditions. The proposed DVR controller is able to detect balanced, unbalanced and single phase voltage sags. A novel reference voltage generation method is also presented. To validate the proposed control methods, a 3-phase DSP controlling a DVR prototype with a power rating of 1.5-kVA has been developed. Finally, experimental results are presented to verify the performance of the proposed control methods.
Implementation of Fuzzy Logic Controller Using Fortran Language in Pscad/Emtdc
(Sage Publications Ltd, 2011) Teke, Ahmet; Meral, M. Emin; Saribulut, Lutfu; Tumay, Mehmet
Fuzzy logic controllers have gained widespread use by engineers and practitioners due to their design simplicity, closeness to human reasoning and suitability for control applications. Fuzzy logic controlled studies are usually performed in MATLAB, or sometimes in PSCAD/EMTDC (Power Systems Computer Aided Design/Electromagnetic Transient including d.c.) with MATLAB interfacing. The PSCAD/EMTDC software does not include a component for a fuzzy logic controller. This paper is, to the best of our knowledge, the first work that designs and implements a fuzzy logic controller in PSCAD/EMTDC by using FORTRAN codes. In this way, several drawbacks which arise from the interfacing between MATLAB and PSCAD/EMTDC are eliminated. The simulation section of this paper consists of a case study based on a fuzzy logic-controlled PWM inverter in which the performance of the developed fuzzy logic controller is evaluated.
Performance Comparison of Pwm Methods for 27-Level Hybrid Multilevel Inverters
(Gazi Univ, 2012) Saribulut, Lutfu; Meral, M. Emin; Teke, Ahmet; Tumay, Mehmet
Multilevel inverters have become more popular due to reduced switching losses, low costs, low harmonic distortion and high-voltage capability when compared to traditional PWM inverters. A new family of multilevel inverters that has decreased the number of separated DC sources has emerged named as hybrid multilevel inverter. In this study, theories and applications of four PWM modulation methods for 27 level hybrid multilevel inverters are examined. The comparative case studies are presented to validate the examined modulation technique through harmonic spectrum analysis, output voltage magnitude, THD, WTHD and simulation using Power System Computer Aided Design Program (PSCAD).