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121 results on '"KATIC, V."'

1. New String Reconfiguration Technique for Residential Photovoltaic System Generation Enhancement

Author

CORBA, Z., KATIC, V., POPADIC, B., and MILICEVIC, D.

Subjects
inverters, photovoltaic systems, simulation, smart grids, solar power generation, Electrical engineering. Electronics. Nuclear engineering, TK1-9971, Computer engineering. Computer hardware, TK7885-7895
Abstract

Improvement of photovoltaic (PV) power plant performance under partial shading conditions aiming to increase electrical energy generation is in the focus of this research. This paper proposes the performance optimization of PV power plant under partial shading conditions by new PV string reconfiguration technique. The Matlab/Simulink model is used to simulate the operation of the PV string under partial shading conditions and with the proposed recombination technique. Simulated operational conditions have experimentally been verified by string characteristics measurement on the existing roof-top PV system at the Faculty of Technical Sciences in Novi Sad. Simulation and experimental results showed a high degree of matching, while the obtained values proved that proposed method leads to output power increase and higher PV system generation in PV string operation under partial shading.

Published
2016
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2. Least Squares Modeling of Voltage Harmonic Distortion Due to PC Cluster Operation

Author

KATIC, V., RADULOVIC, V., DJUKANOVIC, S., MUJOVIC, S., and RASOVIC, M.

Subjects
load modeling, total harmonic distortion, voltage measurement, Electrical engineering. Electronics. Nuclear engineering, TK1-9971, Computer engineering. Computer hardware, TK7885-7895
Abstract

Regarding the possibility of harmonic generation, personal computers (PCs) are very significant within the category of non-linear low power loads. In modern distribution systems, the number of PCs simultaneously connected to distribution grid constantly increases. This PC clustering can negatively affect the quality of supply. The paper deals with mathematical modeling of the voltage total harmonic distortion (THDU) caused by operation of PC cluster. The proposed model is based on the power quality measurements carried out in a computer centre and computer simulations. It takes into account the THDU dependence on the PC cluster size and grid stiffness. Model parameters are derived in the least squares sense. The influences of cable cross-section and pre-existing THDU of the phase voltage are also discussed. The accuracy of the proposed model is confirmed by additional measurements performed in a commercial building.

Published
2013
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3. New Space Vector Selection Scheme for VSI Supplied Dual Three-Phase Induction Machine

Author

MILICEVIC, D., KATIC, V., CORBA, Z., and GRECONICI, M.

Subjects
digital signal processor, dual three-phase induction motor, space vector pulse width modulation, vector space decomposition, voltage source inverter, Electrical engineering. Electronics. Nuclear engineering, TK1-9971, Computer engineering. Computer hardware, TK7885-7895
Abstract

This paper presents a novel space vector selection scheme applicable for the control of dual three-phase induction motor drives supplied from a six-phase voltage source inverter (VSI). The vector selection method is based on the vector space decomposition technique (VSD). Unique vector selection pattern simplifies problems related to complicated implementation of standard VSD in commercially available digital signals processors (DSP). The proposed vector selection scheme is verified through a theoretical analysis, computer simulations and practical experimental results conducted on a dual three-phase test rig prototype with control algorithm implemented in Texas Instrument?s TMS320F2808 DSP.

Published
2013
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4. The Hybrid Method for On-line Harmonic Analysis

Author

KNEZEVIC, J. M. and KATIC, V. A.

Subjects
adaptive filters, discrete Fourier transforms, harmonic analysis, power electronics and power quality, Electrical engineering. Electronics. Nuclear engineering, TK1-9971, Computer engineering. Computer hardware, TK7885-7895
Abstract

The novel hybrid method of the Discrete Fourier Transform (DFT) and the Enhanced Phase-Locked Loop (EPLL) has been presented. The original well-known methods and the Hybrid method have been analysed and tested in several simulations and experiments. The methods are implemented on the Digital Signal Processor and compared in a real time power quality application. Although it requires a bit higher computational effort, the Hybrid method compared to original methods shows advantages for on-line harmonic analysis.

Published
2011
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5. The Impact of the Load Side Parameters on PC Cluster's Harmonics Emission

Author

KATIC, V. A., MUJOVIC, S. V., RADULOVIC, V. M., and RADOVIC, J. S.

Subjects
PC clusters, power conversion, harmonics, Electrical engineering. Electronics. Nuclear engineering, TK1-9971, Computer engineering. Computer hardware, TK7885-7895
Abstract

Harmonics current emission from personal computers (PCs) is of special interest to power quality researchers, due to their wide spread application and the fact that they are usually concentrated in large groups (clusters). The input current total harmonic distortion (THDI) dependence on number of connected PCs in a cluster (NPC) is affected by network parameters and load side parameters of each cluster's PC simultaneously. As the impact of grid parameters on the THDI=f(NPC) dependence is analyzed in the author's previous papers, special emphasis is given on the impact of the DC side smoothing capacitor (C) in PCs power supply unit. For engineering application it is convenient to present the THDI=f(NPC) function with simple mathematical expressions which include these effects. In the paper authors are proposing an improved mathematical expression to presents impact of load side (DC capacitance) parameters. To achieve this goal, results of the measurements of harmonic emission from a large computer center with 167 clustered PCs and the computer simulation for even larger number of PCs are used.

Published
2011
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6. Initial Results of Multilevel Principal Components Analysis of Facial Shape

Author

Farnell, D. J. J., Galloway, J., Zhurov, A., Richmond, S., Perttiniemi, P., Katic, V., Diniz Junqueira Barbosa, Simone, Series editor, Chen, Phoebe, Series editor, Du, Xiaoyong, Series editor, Filipe, Joaquim, Series editor, Kara, Orhun, Series editor, Kotenko, Igor, Series editor, Liu, Ting, Series editor, Sivalingam, Krishna M., Series editor, Washio, Takashi, Series editor, Valdés Hernández, María, editor, and González-Castro, Víctor, editor

Published
2017
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11. Fault Analysis and Field Experiences of Central Inverter Based 2 MW PV Plant

Author

Dumnic, B., Liivik, E., Dragan Milicevic, Popadic, B., Katic, V., and Blaabjerg, F.

Subjects
Photovoltaics, Faults, PV power plant, Reliability, Real field measurements
Abstract

Reliability of photovoltaic (PV) components, systems and operation plays significant role in marketability of PV power plants. In that regard special attention should be given to the activities oriented at reliability improvement. Considering the quantity of parameters that could influence the operation of PV system, a number of different fault manifestations can be expected. The paper presents a classification of photovoltaic (PV) power system faults and has a root cause analysis oriented towards reliability improvement and thereby being able to reduce the overall capital and operational cost. The analysis is based on long-term field experience of operation and maintenance (O&M) of a central inverter based 2 MW PV power plant. Practical reliability improvement suggestions are also given.

Published
2018

14. Use of Screen-printed Electrodes Modified by Prussian Blue and Analogues in Sensing of Cysteine

Author

Bonacin, JA, Dos Santos, PL, Katic, V, Foster, CW, Banks, CE, Bonacin, JA, Dos Santos, PL, Katic, V, Foster, CW, and Banks, CE

Abstract

© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim The utilisation of screen-printing technology allows for a mass scalable approach for the production of electrochemical screen-printed electrodes (SPEs) and the presence of a redox mediator can add new possibilities to the electrochemical properties of the SPEs. Among the materials used as redox mediators, cyanidoferrates polymers can be used for electro-oxidation of cysteine. In this work, two monomers, namely, [Fe(CN) 6 ] 4− and [Fe(CN) 5 NH 3 ] 3− were used to produce Prussian blue (PB) and Prussian blue-Ammine (PB-Ammine), respectively. In addition, two modification methods were compared, firstly via a drop-casting and secondly by the incorporation of these materials into a printable ink. The SPE modified by PB-Ammine (drop-casting) exhibits the highest electroactive area, however the highest heterogeneous rate constant was found with the SPE modified by PB-Ammine that was incorporated into the ink. The highest value of the constant of electro-oxidation of cysteine and lowest limit of detection was also observed in the SPE modified by PB incorporated into the ink. These studies suggest that the electrocatalytic properties of SPE modified by PB and PB-Ammine are dependent upon the availability of Fe 3+ catalytic sites and the increased kinetics of the chemical reaction between the catalytic sites and the analyte.

Published
2017

15. Feedback of Individual Genetic Results to Research Participants: Is It Feasible in Europe?

Author

Budin-Ljosne, I, Mascalzoni, D, Soini, S, Machado, H, Kaye, J, Bentzen, HB, Rial-Sebbag, E, D'Abramo, F, Witt, M, Schamps, G, Katic, V, Krajnovic, D, Harris, JR, Budin-Ljosne, I, Mascalzoni, D, Soini, S, Machado, H, Kaye, J, Bentzen, HB, Rial-Sebbag, E, D'Abramo, F, Witt, M, Schamps, G, Katic, V, Krajnovic, D, and Harris, JR

Abstract

BACKGROUND: There is growing consensus that individual genetic research results that are scientifically robust, analytically valid, and clinically actionable should be offered to research participants. However, the general practice in European research projects is that results are usually not provided to research participants for many reasons. This article reports on the views of European experts and scholars who are members of the European COST Action CHIP ME IS1303 (Citizen's Health through public-private Initiatives: Public health, Market and Ethical perspectives) regarding challenges to the feedback of individual genetic results to research participants in Europe and potential strategies to address these challenges. MATERIALS AND METHODS: A consultation of the COST Action members was conducted through an email survey and a workshop. The results from the consultation were analyzed following a conventional content analysis approach. RESULTS: Legal frameworks, professional guidelines, and financial, organizational, and human resources to support the feedback of results are largely missing in Europe. Necessary steps to facilitate the feedback process include clarifying legal requirements to the feedback of results, developing harmonized European best practices, promoting interdisciplinary and cross-institutional collaboration, designing educational programs and cost-efficient IT-based platforms, involving research ethics committees, and documenting the health benefits and risks of the feedback process. CONCLUSIONS: Coordinated efforts at pan-European level are needed to enable equitable, scientifically sound, and socially robust feedback of results to research participants.

Published
2016

17. A flexible solid-state pulsed power topology

Author

Katic, V, Boroyevich, D, Davari, Pooya, Zare, Firuz, Ghosh, Arindam, Katic, V, Boroyevich, D, Davari, Pooya, Zare, Firuz, and Ghosh, Arindam

Abstract

Advances in solid-state switches and power electronics techniques have led to the development of compact, efficient and more reliable pulsed power systems. This paper proposes an efficient scheme that utilizes modular switch-capacitor units in obtaining high voltage levels with fast rise time (dv/dt) using low voltage solid-state switches. The proposed pulsed power supply has flexibility in terms of controlling energy and generating broad range of voltage levels. The energy flow can be controlled as the stored energy can be adjusted by a current source utilized at the first stage of the system. Desirable voltage level can be obtained by connecting adequate number of switch-capacitor units. Moreover, the proposed topology is load independent. Therefore it can easily supply wide range of applications especially the low impedance ones. The effectiveness of the proposed approach is verified by simulations

Published
2012

39. Power quality compensation using universal power quality conditioning system.

Author

Graovac, D., Katic, V., and Rufer, A.

Abstract

The aim of this letter is to present a universal power quality conditioning system (UPQS) named after a unified power quality conditioner (UPQC), which is extended by adding a shunt active filter at the load side. Its main purpose is to compensate for supply voltage and load current imperfections, such as sags, swells, interruptions, imbalance, flicker, harmonics, reactive currents, and current unbalance. Converter and control analysis is presented together with results showing the UPQS modes of operation. [ABSTRACT FROM PUBLISHER]

Published
2000
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40. Universal power quality system - an extension to universal power quality conditioner

Author

Graovac, D., Katic, V., and Rufer, A.

Subjects
converter control, power conditioners, active filters
Abstract

The aim of this paper is to present a universal power quality conditioning system (UPQS) which consists of a unified power quality conditioner (UPQC) extended by adding a shunt active filter at the load side. Such system has heiger harmonic compensation characteristic, since there are no problem associated with passive filter operation. Its main purpose is to compensate for supply voltage and load current imperfections, such as: sags, swells, interruptions, imbalance, flicker, harmonics, reactive currents and current unbalance. After determination of classical active filtering drawbacks, UPQS converter and control analysis is presented, together with results showings the UPQS modes of operation.

41. Unified power quality conditioner based on current source converter topology

Author

Graovac, D., Katic, V., Rufer, A., and Knezevic, J.

Subjects
converter control, harmonics, active filters, power quality
Abstract

Nonlinear devices, such as power electronics converters, inject harmonic currents in the AC system and increase overall reactive power demanded by the equivalent load. Also, the number of sensitive loads that require ideal sinusoidal supply voltages for their proper operation has increased. In order to keep power quality under limits proposed by standards, it is necessary to include some sort of compensation. Different types of power quality compensators of higher or lower complexity have been reported. The aim of this paper is to present a unified power quality conditioner (UPQC) that consists of two three-phase current-source converters connected on the same inductive DC link. Such system has faster phase voltage control loop than its voltage-source converter based counterpart, as well as the inherent short circuit protection capability. Also, in this case passive filter connection between UPQC and the load is not needed, which minimizes the cost of the system.

42. Solving supply and load imperfections using universal power quality conditioning system

Author

Graovac, D., Katic, V., and Rufer, A.

Subjects
active filter, supply network, active rectifier, harmonic compensation, power quality, UPQS
Abstract

The aim of this paper is to present a universal power quality conditioning system (UPQS) which consists of a unified power quality conditioner (UPQC) extended by adding a shunt active filter at the load side. Such system has higher harmonic compensation characteristic, since there are no problems associated with passive filter operation. Its main purpose is to compensate for supply voltage and load current imperfections, such as: sags, swells, interruptions, imbalance, flicker, harmonics, reactive currents and current unbalance. Converter and control analysis is presented, together with results showing the UPQS modes of operation.

43. Mechanical testing of orthodontic archwires

Author

Katic, V., Zelenika, S., Kamenar, E., Marko Percic, D.Sc., Perčic, M., Špalj, S., Bointon, P., Leach, R., and Southon, N.

Subjects
Nickel-titanium archwires, coating and corrosion, AFM and nanoindentation testing, surface roughness, hardness, Young’s modulus
Abstract

Mechanical properties of orthodontic archwires are studied in this work in the micrometric domain. Measurements are performed on nickel- titanium archwires without and with different coatings as well as subjected for four weeks to an artificial saliva solution with different pH values (4.8 and 6.6). Since surface properties can have a meaningful influence on friction, corrosion or plaque accumulation, surface texture of the wires is measured by employing atomic force microscopy. On the other hand, with the aim of determining Young’s modulus and the hardness, nanoindentation tests are performed for different peak load values. It is hence established that there is no statistically relevant deterioration of the surfaces after their exposure to saliva. Rh coating leads, in turn, to an increase of surface roughness. Young’s moduli and hardness values tend to increase with increasing indentation depths, while they are not meaningfully affected by the coating or the corrosion in saliva.

44. Artificial intelligence based vector control of induction generator without speed sensor for use in wind energy conversion system

Author

Dumnic, B., Popadic, B., Dragan Milicevic, Katic, V., and Oros, D.

Subjects
wind energy, induction generator, rotor speed estimation, MRAS algorithm, artificial intelligence
Abstract

Indirect field oriented control (IFOC) of squirrel-cage induction generator (SCIG) with full capacity power converter used in wind energy conversion system (WECS) is presented in this paper. In order to improve WECS reliability robust IFOC algorithm using artificial intelligence (AI) for speed estimation was developed. Estimated speed is used for realization of maximum power tracking algorithm (MPPT). Practical testing and validation of considered estimation techniques is performed using advance laboratory prototype of WECS. Extensive experimentation is conducted in order to verify efficiency and reliability of proposed speed-sensorless control technique under realistic WECS operating conditions.

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