Papers by Mircea Chindris
Renewable generation, in particular windgeneration, in Romania is a new field that attracts theat... more Renewable generation, in particular windgeneration, in Romania is a new field that attracts theattention of power suppliers, power transport anddistribution companies and specialized committees.Thus new standards are imposed in order to decreasetheir negative effects. Consequently (about theRomanian power system) the study of wind generationimpact on the distribution power grids is needed. Theauthors have studied the theoretical aspects of theimpact on the Romanian power systems of windgenerators and through a study case the realinfluences. Thus the obtained results are presented inthe paper, which contains general aspects about theeffects of wind generation on power systems and astudy case where is underlined the power quality issue.Paper ends with a chapter of conclusions where arereviewed the main aspects and the most importantresults.
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Scientific Bulletin of the ''Petru Maior" University of Tîrgu Mureș, 2009
The segment of loads causing harmonic pollution of power systems is increasing due to the rising ... more The segment of loads causing harmonic pollution of power systems is increasing due to the rising volume of electronic and power electronic components. Each nonlinear load generates periodic events (e.g. harmonics) that could lead to serious problems within power system networks and its components (e.g. transformers). If transformers operate in networks where the harmonic spectra exceed a certain limit, they will additionally be heated up and losses are increased,compared to operation under normal conditions. This paper discusses different effects of harmonics on power ransformers, such as increasing power losses, reduction of efficiency, decrease of power factor and derating of transformers. An economical analysis is performed in order to determinate the life cycle cost of transformers for different rated powers.
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ABSTRACT. The economic scheduling of the generation units is playing a significant role in the en... more ABSTRACT. The economic scheduling of the generation units is playing a significant role in the energy management of the hybrid stand alone microgrid. Energy storage is an increasingly important part of the renewable energy sector because of the need to store power during peak production times for use in off-peak periods. This paper describes an energy management system (EMS) for an islanded microgrid (MG) comprising wind energy conversion system (WECS), photovoltaic (PV), energy storage (ES) system, and microturbine (MT) for calculating the battery charging price (BCP) factor. To reach this objective, firstly the battery system has been modeled using the presented equations then various scenarios is applied by technically limited such as the power, voltage and current applied to charge and discharge of the battery.
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The unbalanced non-sinusoidal operation represents a common steady state of the modern distributi... more The unbalanced non-sinusoidal operation represents a common steady state of the modern distribution power grids. The unbalance is produced by supplying of unbalanced loads or by different unbalanced faults. According to the existing norms, this operating state is evaluated using the well-known negative and zero unbalance factors that practically keep out the harmonic pollution that coexists with the unbalance. The paper proposes a new way of determining the negative and zero unbalance factors, which takes into consideration the non-sinusoidal operating state, too. At the end of the paper, some study cases are analyzed in order to underline the difference between the existing way to evaluate the unbalance in harmonic polluted systems and the proposed one.
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More than ever, electric utilities and industries today are searching for technologies that will ... more More than ever, electric utilities and industries today are searching for technologies that will reduce their operating costs and improve energy savings throughout their systems. New transmission and distribution technologies are now available to help utilities meet these goals. Modern standard grain-oriented silicon steel does give low loss and this loss has been reduced substantially over the years by improvements in treatment, such as cold-rolling and laser-scribing. Future improvements in standard silicon steel losses will be relatively modest. However, amorphous magnetic metal used for transformer cores does give the possibility of decrease core losses compared to standard core steel materials. The magnetic core of this transformer is made with amorphous metal, which is easily magnetized / demagnetized In this paper is presented a comparison between traditional distribution transformers and amorphous distribution transformers. The advantages of amorphous distribution transforme...
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The reduction of energy consumption is a growing concern at the global level. An important domain... more The reduction of energy consumption is a growing concern at the global level. An important domain where the reduction of energy consumption can be achieved is public lighting. Energy charges for street and pedestrian lighting applications represent the largest part of all expenses for public lighting. This is conditioned by many factors, one of them being the use of energy in-efficient lamps and ballasts. This paper's goal is to present and underline possibilities to reduce energy consumption in public lighting systems by the use of energy efficient lamps and ballasts. Some solutions used nowadays to increase efficiency in public lighting are represented in the paper. The results of a search regarding to existing solutions to fulfill the increase of the public lighting network performances will be presented. These will include energy efficient solutions for every type of lamp and energy efficient solutions for lamp and ballast combination used in street and pedestrian lighting a...
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This paper presents the results of an in situ campaign carried on some regions of Romania in orde... more This paper presents the results of an in situ campaign carried on some regions of Romania in order to assess the stage of degradation by corrosion of buried components belonging to power systems. Two issues have been addressed: the first refers to the metallic armor of MV underground cables installed in a variety of soils, in locations with and without DC stray currents; the second one refers to earthing systems located in power substations. The corrosion state was visually analyzed for all studied cables in the zones of contained faults and for the metal conductors of the earthing system. For underground cables, the galvanic continuity of the metallic armors and the insulation resistance between armor and soil, respectively between armor and live conductor were also determined.
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The paper presents a virtual instrument developed for capacitors bank dimension as to compensate ... more The paper presents a virtual instrument developed for capacitors bank dimension as to compensate the reactive power and to raise the power factor in power systems. The mathematical support of the software is accurately described in papers 2 section, along with the negative effects of a low power factor and the advantages of using capacitors banks for reaching the neutral power factor. The 3 section of the paper describes the virtual instrument with its main features and graphical user interface that contains 6 parts. The capacitors bank sizing is made based on the following criterions: reach the power factor imposed by the user, minimum number of capacitors bank steps, and minimum capacitors bank dimensions.
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Classic control systems, based on continuous dimming present some difficulties to adjust their pe... more Classic control systems, based on continuous dimming present some difficulties to adjust their performances to the rapid changes in daylight. Therefore, fuzzy control could be a better solution. The paper analyzes the possibility to implement this new technique in daylighting control and presents the structure of a fuzzy controller proposed by authors; its operation rules and the influence on the imposed value of the illuminance level are also studied.
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First IFAC Workshop on Convergence of Information Technologies and Control Methods with Power Plants and Power Systems (2007), 2007
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Calculul indicatorilor de fiabilitate pentru sisteme complexe impune determinarea parametrilor ec... more Calculul indicatorilor de fiabilitate pentru sisteme complexe impune determinarea parametrilor echivalenţi (intensităţi de defectare λe şi de reparare/înlocuire μe/υe) ataşaţi diagramelor bloc ce descriu comportarea acestor sisteme. Literatura de specialitate prezintă formulele de calcul pentru λe şi μe (υe) în cazul diferitelor scheme conţinând combinaţii de elemente conectate în serie şi/sau paralel. Totuşi, aceste relaţii sunt greu de aplicat, în special în cazul sistemelor complexe, cu caracter general, în care pot apărea n elemente serie (de acelaşi tip sau diferite) cu m elemente paralel, în diverse combinaţii. Autorii propun modelarea elementelor componente ale schemelor bloc prin tipuri abstracte de date cu doi parametri (λ şi μ), pentru care se definesc o serie de operaţii. Odată cu realizarea acestei modelări, toate elementele diagramelor bloc vor fi tratate ca obiecte de tip „parametru de fiabilitate“ urmând ca obţinerea parametrilor echivalenţi (λe şi μe), precum şi a in...
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Advanced Engineering Forum, 2013
The concept of microgrid was first introduced in 2001 as a solution for reliable integration of d... more The concept of microgrid was first introduced in 2001 as a solution for reliable integration of distributed generation and for harnessing their multiple advantages. Specific control and energy management systems must be designed for the microgrid operation in order to ensure reliable, secure and economical operation; either in grid-connected or stand-alone operating mode. The problem of energy management in microgrids consists of finding the optimal or near optimal unit commitment and dispatch of the available sources and energy storage systems so that certain selected criteria are achieved. In most cases, energy management problem do not satisfy the Bellman's principle of optimality because of the energy storage systems. Consequently, in this paper, an original fast heuristic algorithm for the energy management on stand-alone microgrids, which avoids wastage of the existing renewable potential at each time interval, is presented. A typical test microgrid has been analysed in or...
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Proceedings of the 41st International Universities Power Engineering Conference, 2006
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Electric Power Systems Research, 2013
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energy-cie.ro
Abstract: In the last decades, commercial electric customers have become increasingly interested ... more Abstract: In the last decades, commercial electric customers have become increasingly interested in the relative quality of the power they purchase as their businesses rely more heavily on modern high-tech processes. The utilization of power electronic control ...
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Energies, 2013
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The economic scheduling of the generation units is playing a significant role in the energy manag... more The economic scheduling of the generation units is playing a significant role in the energy management of the hybrid stand alone microgrid. Energy storage is an increasingly important part of the renewable energy sector because of the need to store power during peak production times for use in off-peak periods. This paper describes an energy management system (EMS) for an islanded microgrid (MG) comprising wind energy conversion system (WECS),photovoltaic (PV), energy storage (ES) system, and microturbine (MT) for calculating the battery charging price (BCP) factor. To reach this objective, firstly the battery system has been modeled using the presented equations then various scenarios is applied by technically limited such as the power, voltage and current applied to charge and discharge of the battery.
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Renewable Energy and Power Quality Journal
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Papers by Mircea Chindris