- Romania
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... 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.
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... 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.
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... 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 distribution power grids. The unbalance is produced by supplying of unbalanced loads or by different unbalanced faults. According to the existing... 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 reduce their operating costs and improve energy savings throughout their systems. New transmission and distribution technologies are now... 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 where the reduction of energy consumption can be achieved is public lighting. Energy charges for street and pedestrian lighting applications... 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 order to assess the stage of degradation by corrosion of buried components belonging to power systems. Two issues have been addressed: the first... 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 the reactive power and to raise the power factor in power systems. The mathematical support of the software is accurately described in papers... 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 performances to the rapid changes in daylight. Therefore, fuzzy control could be a better solution. The paper analyzes the possibility to... 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.
Research Interests: Engineering and Elsevier
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.... 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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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... 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...
Research Interests: Computer Science, Heuristics, Electric Energy Storage, Distributed Generation, Electrochemical Energy Storage Device, and 15 moreElectric Power Systems, Energy Management, Microgrid, Energy Management and Policy Planning, Energy Storage, Mathematical Optimization, Electrical Power Distribution Network Optimization with Distributed Generation and Smartgrids, Distributed Generations, Micro Grid, Micro Grid Electrical Systems, Heuristic Methods, Microgrid Energy Management, Microgrid control, Electrical Power Distribution, and Load Shedding In Microgrid
Research Interests: Graph Theory, Critical, Power System Economics, Power System Reliability, Reliability, and 15 moreSwitching circuits, Sub-station, Tk, Network Topology, Switchgear, Circuit Diagram, Substations, Power Grids, Power Generation Economics, Circuit Topology, Circuit Breakers, Electrical Substation, Critical Equipment, Electrical Substations, and Power Line
Research Interests: Electrical Engineering, Artificial Intelligence, Genetic Algorithms, Distributed Generation, Artificial Inteligence, and 15 moreDistributed System, Electrical, Genetic Algorithm, Electric Power Systems, Electrical Power Distribution Network Optimization with Distributed Generation and Smartgrids, Distribution network, Distribution Generation, Control Reconfiguration, Algorithms on Trees and Graphs, Electrical Power Distribution, E, Dispersed Generation, Electrical And Electronic Engineering, Distribution System Reconfiguration, and Genetic
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... 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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Research Interests: Engineering, Computer Science, Artificial Intelligence, Distributed Generation, Electric Power Systems, and 15 moreElectrical Power System, Distribution System, Economic Power Dispatch, FACTS Devices, Distribution systems, Electrical Power System Modelling and and Load Flow Analysis, Artificial Intelligence applications, Algorithms on Trees and Graphs, Economic Load Dispatch Using Metaheuristic Techniques, Enhanced Genetic Operators, For Power Distribution System Reconfiguration, A New Heuristic Approach for Distribution System Reconfiguration Considering Power Losses Cost and Damage Cost Due to Power Supply Interruption of Consumers Heuristic Approach, Distribution Network Reconfiguration Considering Power Losses and Outages Costs Using Genetic Algorithm, ENERGIES, and Distribution System Optimization
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... 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.
Research Interests:
Research Interests: Structura, Sen, Energetica, Statii Electrice, Echipamente Critice, and 15 moreInstalatii De Conexiuni, Scheme Conexiuni, Retehnologizare, Sistemul Energetic National, Bare Colectoare, Statii De Transformare, Statii Electrice De Transformare, Retele Electrice, Sisteme Electroenergetice, Fiabilitate, Siguranta In Functionare, Structuri, Scheme Statii Electrice, Scheme De Conexiuni, and structura SEN
ABSTRACT 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... more
ABSTRACT 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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Research Interests:
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For harmonic polluted electrical networks, the load flow calculation consists in the determination of steady state quantities for each harmonic component at a time. On the other hand, the load flow calculation for unbalanced/asymmetrical... more
For harmonic polluted electrical networks, the load flow calculation consists in the determination of steady state quantities for each harmonic component at a time. On the other hand, the load flow calculation for unbalanced/asymmetrical electric networks consists in the determination of steady state quantities for each phase at a time. The theoretical relationships proposed in literature are complex and it is difficult to implement them in harmonic polluted and unbalanced/asymmetric complex systems containing many elements, in various combinations. In this paper, the authors propose to model the harmonic complex three-phase quantities through abstract data types. As a result, electrical engineering laws, as Ohm or Kirchhoff, are reduced to simplified expressions corresponding to fundamental harmonic component single-phase case.
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The growth of distributed generation (DG) which is consumer driven and not centrally planned presents a number of challenges and opportunities specific mainly to low voltage (LV) distributed networks. The growth of DG in order to meet the... more
The growth of distributed generation (DG) which is consumer driven and not centrally planned presents a number of challenges and opportunities specific mainly to low voltage (LV) distributed networks. The growth of DG in order to meet the UK government’s environmental targets for 2010 will taken into consideration for example the following LV distribution network constraints: steady-state voltage limits, voltage unbalanced limits and harmonic limits. This paper presents an algorithm developed by the authors in order to perform load flow calculation in unbalanced and harmonic polluted low voltage radial networks with distributed generation. The authors propose to model the harmonic complex quantities (a set of complex quantities correspon ding to each harmonic component) through
abstract data types with complex parameters. For harmonic polluted and nbalanced radial electric networks that include distributed generators, it was considered the backward/forward sweep with some specifications and adaptations.
abstract data types with complex parameters. For harmonic polluted and nbalanced radial electric networks that include distributed generators, it was considered the backward/forward sweep with some specifications and adaptations.
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The optimization in the operation of distribution electric systems has become an acute problem. In order to evaluate some essential criteria (e.g., active power losses) the computation of power flow is absolutely necessary. Taking into... more
The optimization in the operation of distribution electric systems has become an acute problem. In order to evaluate some essential criteria (e.g., active power losses) the computation of power flow is absolutely necessary. Taking into account the real operating conditions (unbalance, harmonics) it is of great interest for accurate steady state estimation. The existent solutions proposed in literature are complex and it is difficult to implement them in unbalanced and harmonic polluted systems. By the original adaptation of the backward/forward sweep algorithm, the authors propose a novel paradigm to analyze the propagation of asymmetries and harmonic distortions through radial electric networks.
Research Interests: Harmonic Analysis, Object Oriented Programming, Distribution Networks, Steady-State, Power transformers, and 12 moreDistribution systems, Harmonic distortion, Electrical Power Distribution Systems, Unbalanced Electric Networks, Load Flow, Backward/forward, Objects Oriented Programming, Power System Harmonics, Adaptation Models, Harmonic Polluted Distribution Systems, Object Oriented Backward/forward Algorithm, and Radial Electric Systems
Research Interests: Decision Making, Power Quality, Genetic Algorithms, Multi Criteria Decision Making, Algorithm, and 56 moreDesign and Analysis of Algorithms, Optimization Methods, Distribution Networks, Optimisation, Multicriteria decision making, Reliability, NSGA, Load Balancing, Search Algorithm, Distribution System, Algorithm Design and analysis, Network Topology, Reconfiguration, Pareto front, Power Losses, Power Distribution Reliability, Co Opted State Reconfiguration, Pareto Optimality, Dispersed Generation, Pareto Frontier, Reconfiguration NSGA, Optimal Distribution System Reconfiguration, Power Losses Reduction, Microgenetic Multiobjective Reconfiguration Algorithm, Power Losses and Reliability Indices, Medium Voltage Distribution Network, Microgenetic Multiobjective Reconfiguration Algorithm Considering Power Losses and Reliability Indices for Medium Voltage Distribution Network, Power Supply Quality, Electrical Power Distribution Networks, Evolutionary-based Approach, Microgenetic Multiobjective Reconfiguration, Multiobjective Optimisation Problem, Power System Losses, Reliability Indices, Reconfiguration of Power Distribution Systems, Considering Reliability and Power Loss, Reconfiguration of Power Distribution Systems Considering Reliability and Power Loss, Distribution System Reconfiguration, Probabilistic Reliability Model, Search Problems, 33-bus Distribution System, Power Distribution System Reconfiguration, Power Loss, Probabilistic Reliability Models, Multicriteria Distribution Network Reconfiguration Considering Subtransmission Analysis, Multicriteria Distribution Network Reconfiguration, Considering Subtransmission Analysis, Power Distribution Planning, Power Engineering Computing, Distribution Network Reconfiguration Software, Distribution Operation Planning, Electric Power Distribution Systems, Topological Reconfiguration, Network Reconfiguration, Enhanced Genetic Operators, and Gianfranco Chicco
Nowadays, Renewable Energy Sources and their implementation as Distributed Generation (DG) represent an important issue for power engineering as both are considered to be significant in improving the security of energy supplies by... more
Nowadays, Renewable Energy Sources and their implementation as Distributed Generation (DG) represent an important issue for power engineering as both are considered to be significant in improving the security of energy supplies by decreasing the dependency on imported fossil fuels and in reducing the emissions of greenhouse gases. Unfortunately, c onnecting a lot of small power production units to the
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The analysis of the conducted electromagnetic disturbances propagation is a complex issue, involving detection and analysis of electromagnetic disturbances, modelling of power grids’ elements, and study of the influenceon the grids’... more
The analysis of the conducted electromagnetic disturbances propagation is a complex issue, involving detection and analysis of electromagnetic disturbances, modelling of power grids’ elements, and study of the influenceon the grids’ elements (electric lines and power transformers)of the existing disturbances. Postprint (published version)
Unbalanced line currents produce unequal voltage drops on the three phases of the supply system. Consequently, the phase-to-neutral voltages within the supply system will be unbalanced because the voltage at any point of a power system is... more
Unbalanced line currents produce unequal voltage drops on the three phases of the supply system. Consequently, the phase-to-neutral voltages within the supply system will be unbalanced because the voltage at any point of a power system is the difference between the generated voltage and the voltage drops due to the load current. Due to the negative effects of unbalance currents and voltages, the necessity of studying the propagation phenomenon of this electric disturbance at different voltage levels becomes a pertinent aspect of power quality. This paper presents the propagation process of unbalance through the electric power system, upstream from the LV distribution level. Using the symmetrical components theory, transformers with different types of connections are studied thus conclusions are taken regards transformers influence on the unbalance propagation.
In the last decade the rapid development of PC (personal computers) and computer science technologies encouraged their utilization in different technical disciplines, particularly in power engineering. Indeed, power engineers choose often... more
In the last decade the rapid development of PC (personal computers) and computer science technologies encouraged their utilization in different technical disciplines, particularly in power engineering. Indeed, power engineers choose often to solve problems that appear in the power systems with the help of dedicated software tools or advanced technologies based on computers. This approach is chosen first of all due to the financial perspective. For example measurements with the help of computers (virtual instruments) costs less than the classic methods that supposes the implication of great human and materials resources. On the other hand this approach implies a faster speed in finding a viable solution. The use of computers in technology is realized with the support of software tools and/or hardware components. The first category is less expensive and accessible. The paper presents a software tool special created for signals generation by describing its graphical interface and worki...
Almost all bulk electric power is generated, transported and consumed in an alternating current (AC) network. Elements of AC systems produce and consume two kinds of power: real power (measured in watts) and reactive power (measured in... more
Almost all bulk electric power is generated, transported and consumed in an alternating current (AC) network. Elements of AC systems produce and consume two kinds of power: real power (measured in watts) and reactive power (measured in volt-amperes reactive or VAr). Real power accomplishes useful work (e.g., running motors and lighting lamps); reactive power supports the voltages that must be controlled for system reliability. The industrial consumers normally contain high power single-phase receivers as mains frequency induction furnaces, welding transformers etc. If the load is unbalanced, the reactive power absorption on each phases are also unsymmetrical. In this case the three phase reactive compensation can have negative consequences; some phases may be over-compensating other lesscompensating. In this paper, the authors propose a new strategy to improve the power factor using single phase capacitor for strongly unbalanced loads. Every capacitor is connected through a static c...