Electric Power Distribution

Acea Distribuzione è una delle utility più importanti a livello nazionale nella distribuzione di elettricità (seconda per numero di utenze connesse); gestisce il servizio di distribuzione dell'energia elettrica ad alta, media e bassa tensione nei Comuni di Roma e Formello, servendo 2,7 milioni di abitanti, con un totale di 70 Cabine Primarie e 13.000 cabine MT/BT. L'introduzione del concetto di Smart Grid solleva l'assunzione che la produzione di energia sia una prerogativa esclusiva delle centrali in alta tensione e che i flussi energetici sulle reti di distribuzione possano essere considerati unidirezionali (dal nodo di scambio in alta tensione verso i nodi passivi delle utenze in media e bassa tensione). Ciò impone una nuova forma di gestione del sistema elettrico, in cui "l'intelligenza" (ossia funzioni di controllo e dispacciamento dei flussi energetici) non sia più confinata esclusivamente alla rete di trasmissione, deputata a interconnettere i nodi attivi di produzione ai nodi di scambio con le reti di distribuzione sottese (fino a ieri completamente passivi), ma che coinvolga anche i numerosi ed eterogenei nodi delle reti di distribuzione. ACEA Distribuzione ha implementato la Smart Grid sulla rete di distribuzione della città di Roma seguendo quattro fattori di innovazione:

Somalia has been experiencing challenges in the distribution of power to the whole country in the past decades. As a result, more than half of Somalia population is affected by the ineffectiveness of the distribution of electricity which lowers their standard of living. A distribution network is one of the main parts of a power system as it is connected directly to the load center and can act as a microgrid during an islanding operation. The concept of integrating both renewable and distributed energy sources at the distribution level is currently of great interest for power system engineers. Further research by power companies and engineers on applying better techniques to improve the power quality and stability of dynamic devices in a distribution network is ongoing. This Research Paper presents a comparative study of radial and ring type electrical power distribution system. Power distribution systems play a significant role, since it is the main link between the power substation and the consumers. Presently power distribution system is done by the radial type system and it has only one path for power flow from distribution substation and to the particular load. The another type of power distribution is ring system and it has one or more paths between the distribution substation and the load. This increases the reliability over the radial distribution system by the quality supply. A five bus distribution system is considered to compare the two different type of systems. The module of distribution system is implemented using the MATLAB/SIMULINK R2014a. The experimental results reveal that the ring type distribution system is more reliable compare to that of the radial distribution system.

The primary issues affecting energy options are those of availability, affordability, sustainability, and security. Since energy resources are unevenly distributed around the world, and the impacts of energy consumption have global reach in both environmental and political terms, any meaningful review of energy-related issues must take a global perspective. This work synopsizes world and national energy issues (including energy source options, resource stocks, and future prognosis) in the context of how Army installations need to respond to changing trends. This report presents implications of actions that may be taken in response to the national and world energy situation, to help the Army to make informed choices on energy utilization that will contribute to sustaining the Army's mission.

This paper discusses the effects of Hurricane Maria on Puerto Rico’s electric grid. Arguably, the most significant effect of Hurricane Maria on Puerto Rico was the electric power outage that initially affected the entire island and lasted more than ten months. Although the damage to the conventional electric power generation infrastructure was relatively minor, both the transmission and distribution portions of the grid suffered much worse damage than that observed during other hurricanes that affected the U.S. in the past decade. This extensive damage added to logistical limitations and the island orography were important factors that contributed to an extremely slow restoration process leading to a very low resilience for the island’s power grid. This paper describes all these aspects in detail and supports the explanation of the hurricane effects with photographic evidence collected during a damage assessment conducted in the early December 2017 when about half of the electricity...

The performance of a photovoltaic (PV) array is affected by temperature, solar insolation, shading, and array configuration. Often, the PV arrays get shadowed, completely or partially, by the passing clouds, neighboring buildings and towers, trees, and utility and telephone poles. The situation is of particular interest in case of large PV installations such as those used in distributed power generation schemes. Under partially shaded conditions, the PV characteristics get more complex with multiple peaks. Yet, it is very important to understand and predict them in order to extract the maximum possible power. This paper presents a MATLAB-based modeling and simulation scheme suitable for studying the I-V and P-V characteristics of a PV array under a nonuniform insolation due to partial shading. It can also be used for developing and evaluating new maximum power point tracking techniques, especially for partially shaded conditions. The proposed models conveniently interface with the models of power electronic converters, which is a very useful feature. It can also be used as a tool to study the effects of shading patterns on PV panels having different configurations. It is observed that, for a given number of PV modules, the array configuration (how many modules in series and how many in parallel) significantly affects the maximum available power under partially shaded conditions. This is another aspect to which the developed tool can be applied. The model has been experimentally validated and the usefulness of this research is highlighted with the help of several illustrations. The MATLAB code of the developed model is freely available for download.

This paper provides a review of the research conducted on complex network analysis (CNA) in electric power systems. Moreover, a new approach is presented to find optimal locations for microgrids (MGs) in electric distribution systems (EDS) utilizing complex network analysis. The optimal placement in this paper points to the location that will result in enhanced grid resilience, reduced power losses and line loading, better voltage stability, and a supply to critical loads during a blackout. The criteria used to point out the optimal placement of the MGs were predicated on the centrality analysis selected from the complex network theory, the center of mass (COM) concept from physics, and the recently developed controlled delivery grid (CDG) model. An IEEE 30 bus network was utilized as a case study. Results using MATLAB (MathWorks, Inc., Nattick, MA, USA) and PowerWorld (PowerWorld Corporation, Champaign, IL, USA) demonstrate the usefulness of the proposed approach for MGs placement.

We propose, describe, and model a competitive joint venture (CJV) institution as an alternative to traditional natural monopoly regulation of the wires portion of the electricity supply chain. This CJV institution consists of an ownership rule and a wires access charge determination rule, with wires use and control rights determined by a firm's market share in the downstream retail market. The wires use rights constitute an alienable property right. By exploiting the vertical structure of the electricity supply chain, this CJV institution can generate superior static and dynamic efficiency results in a model presented and analyzed here. The role of the regulator is one of ex post contractual enforcement; thus this institution is not prone to the information problems associated with traditional natural monopoly regulation. We demonstrate that firstbest efficiency characterizes equilibrium in a pricing model without investment, and that first-best efficiency characterizes the equilibrium of the model with an investment process included under full-information assumptions. * We would like to thank

The primary issues affecting energy options are those of availability, affordability, sustainability, and security. Since energy resources are unevenly distributed around the world, and the impacts of energy consumption have global reach in both environmental and political terms, any meaningful review of energy-related issues must take a global perspective. This work synopsizes world and national energy issues (including energy source options, resource stocks, and future prognosis) in the context of how Army installations need to respond to changing trends. This report presents implications of actions that may be taken in response to the national and world energy situation, to help the Army to make informed choices on energy utilization that will contribute to sustaining the Army's mission.

... most commonly unidirec-tional two-stage converter featuring the step-up (boost) dc-dc converter stage and ... and 400 V to allow for power sharing and voltage regulation using the droop control. ... Starting with the bidirectional grid interface converter, its VI curve is shown at the top ...

The last decades the concern of the public, regarding the possible affects from the exposure to magnetic and electric fields, has grown considerably. This is because the generation, transmission and distribution of electric power are accompanied with the presence of the above mentioned fields. This paper attempts to illustrate the values of the resultant magnetic field in the low frequency range, near a compact kiosk type substation 630KVA, 20-0.4 kV. The measurements were performed in a park, in the city center of Chania, Greece, during summer time. All measured magnetic field values were lower in comparison to the value of 100μΤ introduced by ICNIRP.

Perhaps the most contentious electricity transmission financing issue is cost allocation for new interstate transmission lines-that is, deciding which electricity customers pay how much of the cost of building and operating a new transmission line that crosses several states. This report provides background and analysis of current transmission cost allocation policy and issues.

Abstract: One of the contentious issues in electricity reform is whether there are significant gains from restructuring systems that are moderately well run. South Africa's electricity system is a case in point. The sector's state-owned utility, Eskom, has been generating some of the lowest-priced electricity in the world, has largely achieved revenue adequacy, and has financed the bulk of the government's ambitious electrification program. Moreover, the key technical performance indicators of Eskom's generation plants have reached world-class ...

The reliability theory of repairable systems is vastly different from that of non-repairable systems. The authors have recently proposed a 'decision-based' framework to design and maintain repairable systems for optimal performance and reliability using a set of metrics such as minimum failure free period, number of failures in planning horizon (lifecycle), and cost. The optimal solution includes the initial design, the system maintenance throughout the planning horizon, and the protocol to operate the system. In this work, we extend this idea by incorporating flexibility and demonstrate our approach using a smart charging electric microgrid architecture. The flexibility is realized by allowing the architecture to change with time. Our approach "learns" the working characteristics of the microgrid. We use actual load and supply data over a short time to quantify the load and supply random processes and also establish the correlation between them. The quantified processes are then used to generate load and supply realizations over the long planning horizon. We show how this can reduce the computational effort when simulating microgrids for the entire planning horizon without impeding on their design under various operating scenarios considering uncertainty. 1. Incorrect extrapolations: We must rely on extrapolations of results to consider the entire operating time which Public Release 18. NUMBER OF PAGES 6 19a. NAME OF RESPONSIBLE PERSON

This paper provides a review of the research conducted on complex network analysis (CAN) in electric power systems. Moreover, a new approach is presented to find optimal locations for microgrids (MGs) in electric distribution systems (EDS) utilizing complex network analysis. The optimal placement in this paper points to the location that will result in enhanced grid resilience, reduced power losses and line loading, better voltage stability, and a supply to critical loads during a blackout. The criteria used to point out the optimal placement of the MGs were predicated on the centrality analysis selected from the complex network theory, the center of mass (COM) concept from physics, and the recently developed controlled delivery grid (CDG) model. An IEEE 30 bus network was utilized as a case study. Results using MATLAB (MathWorks, Inc., Nattick, MA, USA) and PowerWorld (PowerWorld Corporation, Champaign, IL, USA) demonstrate the usefulness of the proposed approach for MGs placement.

Towards the complete vision of smarter distribution grid, advanced distribution automation system (ADAS) is one of the major players in this area. In this scope, this paper introduces a generic strategy for cost-effective implementation and evaluation of ADAS. Along with the same line, fault location, isolation and service restoration (FLISR) is one of the most beneficial and desirable applications of ADAS for selfhealing and reliability improvement. Therefore, a localcentralized-based FLISR (LC-FLISR) architecture is implemented on a real, urban, underground medium voltage distribution network. For the investigated network, the complete procedure and structure of the LC-FLISR are presented. Finally, the level of reliability improvement and customers' satisfaction enhancement are evaluated. The results are presented in the form of a comparative study between the proposed automated and non-automated distribution networks. The results show that the automated network with proposed ADAS has a considerable benefit through a significant reduction in reliability indices. In addition, it has remarkable benefits observed from increasing customers' satisfaction and reducing penalties from industry regulators.

The authors have recently proposed a 'decision-based' framework to design and maintain repairable systems. In their approach, a multiobjective optimization problem is solved to identify the best design using multiple short and long-term statistical performance metrics. The design solution considers the initial design, the system maintenance throughout the planning horizon, and the protocol to operate the system. Analysis and optimization of complex systems such as a microgrid is however, computationally intensive. The problem is exacerbated if we must incorporate flexibility in terms of allowing the microgrid architecture and its running protocol to change with time. To reduce the computational effort, this paper proposes an approach that "learns" the working characteristics of the microgrid and quantifies the stochastic processes of the total load and total supply using autoregressive time-series. This allows us to extrapolate the microgrid operation in time and eliminate therefore, the need to perform a full system simulation for the entire long-term planning horizon. The approach can be applied to any repairable system. We show that building in flexibility in the design of repairable systems is computationally feasible and leads to better designs.

This paper explains conflict over technological process innovation in cultural terms, drawing primarily on a case study of electric power distribution and strategies to automate its operation. The paper shows how different occupational cultures, "operators" and "engineers," use different mental models or cognitive representations of technology that are adaptive to their particular work contexts, but which give rise to conflicting evaluations of technological innovation. While these cultural groups may be motivated by a common interest in the successful performance of the technical system, they value different sets of criteria for system design and promising modifications. Despite the apparent contradiction, each perspective is internally consistent and rational. The paper argues that it is beneficial for management to consider these diverse perspectives carefully when planning technological innovation.

Tensions between the energy and water sectors occur when demand for electric power is high and water supply levels are low. There are several regions of the country, such as the western and southwestern states, where the confluence of energy and water is always strained due to population growth. However, for much of the country, this tension occurs at particular times of year (e.g., summer) or when a region is suffering from drought conditions. This report discusses prior work on the interdependencies between energy and water. It identifies the types of power plants that are most likely to be susceptible to water shortages, the regions of the country where this is most likely to occur, and policy options that can be applied in both the energy and water sectors to address the issue. The policy options are designed to be applied in the near term, applicable to all areas of the country, and to ease the tension between the energy and water sectors by addressing peak power demand or decreased water supply.

The performance of a photovoltaic (PV) array is affected by temperature, solar insolation, shading, and array configuration. Often, the PV arrays get shadowed, completely or partially, by the passing clouds, neighboring buildings and towers, trees, and utility and telephone poles. The situation is of particular interest in case of large PV installations such as those used in distributed power generation schemes. Under partially shaded conditions, the PV characteristics get more complex with multiple peaks. Yet, it is very important to understand and predict them in order to extract the maximum possible power. This paper presents a MATLAB-based modeling and simulation scheme suitable for studying the I-V and P-V characteristics of a PV array under a nonuniform insolation due to partial shading. It can also be used for developing and evaluating new maximum power point tracking techniques, especially for partially shaded conditions. The proposed models conveniently interface with the models of power electronic converters, which is a very useful feature. It can also be used as a tool to study the effects of shading patterns on PV panels having different configurations. It is observed that, for a given number of PV modules, the array configuration (how many modules in series and how many in parallel) significantly affects the maximum available power under partially shaded conditions. This is another aspect to which the developed tool can be applied. The model has been experimentally validated and the usefulness of this research is highlighted with the help of several illustrations. The MATLAB code of the developed model is freely available for download.

Cascading failures are one of the main reasons for blackouts in electric power transmission grids. The economic cost of such failures is in the order of tens of billion dollars annually. The loading level of power system is a key aspect to determine the amount of the damage caused by cascading failures. Existing studies show that the blackout size exhibits phase transitions as the loading level increases. This paper investigates the impact of the topology of a power grid on phase transitions in its robustness. Three spectral graph metrics are considered: spectral radius, effective graph resistance and algebraic connectivity. Experimental results from a model of cascading failures in power grids on the IEEE power systems demonstrate the applicability of these metrics to design/optimise a power grid topology for an enhanced phase transition behaviour of the system.

This paper discusses the effects of Hurricane Maria on Puerto Rico's electric grid. Arguably, the most significant effect of Hurricane Maria on Puerto Rico was the electric power outage that initially affected the entire island and lasted more than 10 months. Although damage to the conventional electric power generation infrastructure was relatively minor, both the transmission and distribution portions of the grid suffered much worse damage than that observed during other hurricanes that affected the U.S. in the past decade. This extensive damage added to logistical limitations and the island orography were important factors that contributed to an extremely slow restoration process leading to a very low resilience for the island's power grid. This paper describes all these aspects in detail and supports the explanation of the hurricane effects with photographic evidence collected during a damage assessment conducted in early December 2017 when about half of the electricity customers were still without service. This paper concludes by exploring some lessons from these observations including potential options to increase resilience, such as the use of microgrids.

The objective of the tutorial is to present the results from the CIGRE/CIRED C6.25/B5 Joint Working Group (JWG) that has worked on the control and automation systems for the future electric networks with particular reference to the TSO/DSO interface. The main focus is on the evaluation of the level of automation and control necessary to better manage distribution networks with large penetrations of Distributed Energy Resources (DERs), as seen from both the TSO and DSO perspectives, and to provide services and information about the two level of management (i.e., at TSO and DSO level).

While most of the research work in the field of electrical engineering was aroused by the scientific challenges to be overcome, it is fair to recognize that the practical importance of engineering hinges on its economic impact on the market, the whole society and the environment. Thus, nowadays economic modeling, analysis and optimization of the electricity market is of the utmost significance.This work presents an aggregated economic analysis of the Brazilian electricity distribution companies using an economic model of a regulated market. The fundamental agents (consumer, power utility, government, society) are represented in the TAROT-Optimized Tariff Model, which is applied to the majority of the distribution companies in Brazil, based on public real data available from ANEEL-the Brazilian electrical energy regulatory agency. This reveals the economic flows in the regulated market of each company, and also presents their financial status in terms of over-investments or under investments compared to optimal investments and positive, negative or zero economic value added of each company. Moreover, the model analysis show the socio-economical

U radu je obrađena problematika procjene gubitaka elektricne energije proracunom i mjerenjima. U prvom dijelu predstavljen je nacin bilanciranja elektricne energije u distribuciji i kriticki osvrt na postojeci nacin ocitavanja potrosnje na brojilima potrosaca te prijedlog poboljsanja. Drugi dio rada posvecen je metodama procjene gubitaka u distribucijskoj mreži uz pomoc programske podrske te vrste podataka koji su za tu svrhu potrebni. Treci dio rada bavi se problemom znacenja cijene gubitaka, metodama njihova izracuna i primjerima primjene. Valja istaknuti cetvrti dio rada u kojem je primijenjen model proracuna tokova snaga na temelju mjerenja dijagrama opterecenja u SN mreži, a rezultati proracuna koristeni za zahvate, kojima su gubici u mreži smanjeni. Prikazan je i konkretan nacin smanjenja komercijalnih gubitaka, te prijedlozi kako ih pronaci i ukloniti.

This thesis studies and designs a microgrid with the following characteristics: alternative current, low voltage and grid-connected, features photovoltaic power generation, a suitable storage system and dynamic loads, able to manage zero-net metering with the main grid to which is interfaced. This project also discusses main components of the microgrid providing theoretical principles on how it is modelled using software MATLAB/Simulink, showing graphical results of main simulations operated throughout the work.

With the increasing integration of renewable energy sources into the electricity supply system, planning and operation of power distribution systems has become more complex and challenging. As a consequence of this progress, new and innovative concepts for distribution system operation are in research. Therefore, detailed grid models are required. Due to different power demand and generation according to the region, these grids show a very heterogenous structure. Thus, this paper proposes an approach to synthesize grid models based on the real supply task of German grids.Publicly available data of geoinformation systems, demography, and power generations in combination with a probabilistic approach based on evaluations of real grid data is used to identify the electricity supply task in high spatial resolution. Considering the local supply task, the grid topology is simulated in a two-step heuristic, including a capacitated vehicle routing problem to determine the basic grid topolog...

The reliability theory of repairable systems is vastly different from that of non-repairable systems. The authors have recently proposed a 'decision-based' framework to design and maintain repairable systems for optimal performance and reliability using a set of metrics such as minimum failure free period, number of failures in planning horizon (lifecycle), and cost. The optimal solution includes the initial design, the system maintenance throughout the planning horizon, and the protocol to operate the system. In this work, we extend this idea by incorporating flexibility and demonstrate our approach using a smart charging electric microgrid architecture. The flexibility is realized by allowing the architecture to change with time. Our approach "learns" the working characteristics of the microgrid. We use actual load and supply data over a short time to quantify the load and supply random processes and also establish the correlation between them. The quantified processes are then used to generate load and supply realizations over the long planning horizon. We show how this can reduce the computational effort when simulating microgrids for the entire planning horizon without impeding on their design under various operating scenarios considering uncertainty. 1. Incorrect extrapolations: We must rely on extrapolations of results to consider the entire operating time which Public Release 18. NUMBER OF PAGES 6 19a. NAME OF RESPONSIBLE PERSON

This paper discusses the effects of Hurricane Maria on Puerto Rico’s electric grid. Arguably, the most significant effect of Hurricane Maria on Puerto Rico was the electric power outage that initially affected the entire island and lasted more than 10 months. Although damage to the conventional electric power generation infrastructure was relatively minor, both the transmission and distribution portions of the grid suffered much worse damage than that observed during other hurricanes that affected the U.S. in the past decade. This extensive damage added to logistical limitations and the island orography were important factors that contributed to an extremely slow restoration process leading to a very low resilience for the island’s power grid. This paper describes all these aspects in detail and supports the explanation of the hurricane effects with photographic evidence collected during a damage assessment conducted in early December 2017 when about half of the electricity customer...

The primary issues affecting energy options are those of availability, affordability, sustainability, and security. Since energy resources are unevenly distributed around the world, and the impacts of energy consumption have global reach in both environmental and political terms, any meaningful review of energy-related issues must take a global perspective. This work synopsizes world and national energy issues (including energy source options, resource stocks, and future prognosis) in the context of how Army installations need to respond to changing trends. This report presents implications of actions that may be taken in response to the national and world energy situation, to help the Army to make informed choices on energy utilization that will contribute to sustaining the Army's mission. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents.

Electrification of heating and transportation is poised to disrupt the electric system by increasing distribution system peaks throughout the United States. This paper adds to the literature by describing the main determinants of electric distribution costs using data reported by 101 major U.S. investor-owned utilities and a set of empirical models. These models separately identify the cost of sustaining existing distribution capacity and the cost of expanding capacity to accommodate new load. It is found that growth in system capacity explains less than 10% of capital investments in the distribution system for a typical utility.

This paper discusses the effects of Hurricane Maria on Puerto Rico's electric grid. Arguably, the most significant effect of Hurricane Maria on Puerto Rico was the electric power outage that initially affected the entire island and lasted more than 10 months. Although damage to the conventional electric power generation infrastructure was relatively minor, both the transmission and distribution portions of the grid suffered much worse damage than that observed during other hurricanes that affected the U.S. in the past decade. This extensive damage added to logistical limitations and the island orography were important factors that contributed to an extremely slow restoration process leading to a very low resilience for the island's power grid. This paper describes all these aspects in detail and supports the explanation of the hurricane effects with photographic evidence collected during a damage assessment conducted in early December 2017 when about half of the electricity customers were still without service. This paper concludes by exploring some lessons from these observations including potential options to increase resilience, such as the use of microgrids.

... To achieve a fast dynamic response, the boost converter is primarily controlled by an inner current ... To investigate the performance of the DC-linked microgrid, simulation studies were conducted for a ... [31] A. Al-Hinai, K. Sedhisigarchi, and A. Feliachi, “Stability enhancement of a ...

This paper deals with the assessment of the lightning performance of distribution lines, namely the estimation of the annual number of lightning-induced flashovers versus the critical flashover voltage of the line insulators. The procedure proposed by the authors is compared with the one described in IEEE Std. 1410-2004 Guide for improving the lightning performance of electric power overhead distribution lines. The two methods differ: 1) for the models adopted to evaluate the induced voltages and 2) for the adopted statistical approach. The reasons for differences in the results predicted by the two methods are discussed and the parameters playing the major role in the achievement of the results are identified. The proposed method represents an improvement compared to IEEE Std. 1410 because it takes into account more realistic line configurations and the effect of the finite ground conductivity.

ÖZETÇE: Bu makalede “Çok-yollu Hoparlör Sistemlerinde Güç Dağılımı” konusu ele alınmakta ve Çok-yollu Hoparlör Sistremlerinde Güç Dağılımına ilişkin bir abak sunulmakta ve bu abağın nasıl kullanılacağı örneklerle açıklanmaktadır.
Piyasada bulunan çeşitli “hoparlör transformatörlerinin”, hoparlörlere bağlantıları gösterilmektedir. “LC-elemanlarından oluşmuş Yüksek Fideliteli İki-yollu Bölüştürücü Süzgeç Devresi” ele alınmakta ve bunun devre şemasından montaj şemasına geçiş kısaca açıklanmaktadır.
Çok-yollu hoparlör sistemlerinde kullanılacak olan hoparlörlerin genlik-frekans karekteristikleri yekdiğeriyle kesişmelidir. Karekteristiklerinin kesişme noktası, bir hoparlörden ötekine geçiş sağladığı için “geçişleme” veya “ kesişme” noktası diye adlandırılmaktadır. Öteyandan, karekteristiklerin kesişme noktasındaki frekansa “bölüştürme frekansı” ( cross-over frequency) denmektedir.
Ses frekans görüngesi (spektrumu) boyunca, herbir hoparlörün istenen seviyede akustik enerjiyi yayabilmesi gerekir. Hoparlör seçilirken hem “Duyarlıkları” ( Sensitivity), hem de “Direme Güçleri” (Power Handling Capacity) gözönüne alınacaktır.
2.

The last decades the concern of the public, regarding the possible affects from the exposure to magnetic and electric fields, has grown considerably. This is because the generation, transmission and distribution of electric power are accompanied with the presence of the above mentioned fields. This paper attempts to illustrate the values of the resultant magnetic field in the low frequency

The performance of a photovoltaic (PV) array is affected by temperature, solar insolation, shading, and array configuration. Often, the PV arrays get shadowed, completely or partially, by the passing clouds, neighboring buildings and towers, trees, and utility and telephone poles. The situation is of particular interest in case of large PV installations such as those used in distributed power generation schemes. Under partially shaded conditions, the PV characteristics get more complex with multiple peaks. Yet, it is very important to understand and predict them in order to extract the maximum possible power. This paper presents a MATLAB-based modeling and simulation scheme suitable for studying the I-V and P-V characteristics of a PV array under a nonuniform insolation due to partial shading. It can also be used for developing and evaluating new maximum power point tracking techniques, especially for partially shaded conditions. The proposed models conveniently interface with the models of power electronic converters, which is a very useful feature. It can also be used as a tool to study the effects of shading patterns on PV panels having different configurations. It is observed that, for a given number of PV modules, the array configuration (how many modules in series and how many in parallel) significantly affects the maximum available power under partially shaded conditions. This is another aspect to which the developed tool can be applied. The model has been experimentally validated and the usefulness of this research is highlighted with the help of several illustrations. The MATLAB code of the developed model is freely available for download.

Reconfiguration of a power distribution system consists in changing the functional links among its elements and represents one of the most important actions for the improvement of system performance in operation. In the last few years, some authors have proposed approaches based on Pareto optimality for problem formulation of reconfiguration, with active power losses and reliability indices as objectives. The study highlights the optimization importance of reliability indices which refer to the interruption frequency, especially because, in the context of smart grids, the fastness of the reconfiguration method contributes, by itself, to reduce the duration of interruptions. There is no unique recognition concerning which approach is the most suitable to be used in order to solve the reconfiguration as a Pareto-optimal problem. The most important aspect is the way in which the specific information of the problem field is modelled in the implementation. Also, the dimension of a Pareto-front can vary widely from a test system to another.