Browsing by Author "Tumay, Mehmet"

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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.
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.
Open Unified Power Quality Conditioner With Control Based on Enhanced Phase Locked Loop
(inst Engineering Technology-iet, 2013) Teke, Ahmet; Meral, Mehmet Emin; Cuma, Mehmet Ugras; Tumay, Mehmet; Bayindir, Kamil Cagatay
Open unified power quality conditioner (UPQC) offers different power quality levels with different electricity bill to their users. OPEN UPQC has more flexible modularity than traditional UPQC for field applications. OPEN UPQC consists of two controlled pulse-width modulated shunt and series inverters that have no common DC link. Shunt inverter eliminates current harmonics originating from non-linear load side and series inverter mitigates voltage sag/swell at the point of common coupling caused from faults on transmission system. In this study, controllers for both shunt and series inverters are based on enhanced phase locked loop (E-PLL) and non-linear adaptive filter. For the controller of shunt inverter, proportional integrator controller-based DC-link control strategy is adapted to E-PLL. A fast sag/swell detection method is also presented. Functionalities of OPEN-UPQC system is deeply analysed and tested through simulation studies with power system computer aided design/electromagnetic transients DC analysis program. The test results verify that OPEN UPQC achieves good performance for mitigating the effects of voltage sag/swell and suppressing the load current harmonics.
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).
A Practical Disturbance Generator To Test Performances of Various Power Quality Mitigation Devices
(Tubitak Scientific & Technological Research Council Turkey, 2013) Teke, Ahmet; Meral, Mehmet Emin; Tumay, Mehmet; Cuma, Mehmet Ugras
In this paper, a practical thyristor-based 3-phase sag/swell/outage generator (disturbance generator) is designed to test various power quality mitigation devices (PQMDs), such as solid state transfer switch (SSTS), static voltage compensator (SVC), and uninterruptible power supply. The latest technological disturbance generators (DGs) and the proposed DG are comprehensively discussed and compared with focus on usefulness, economic aspects, and simplicity. The proposed DG is used for experimentally generating different fault conditions and testing a SSTS. The comparisons and analyses show that the proposed DG is an optimum and simple solution to generate sag, swell, unbalance, overvoltage, undervoltage, and outage to test PQMDs.