bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation and Comparison between International Standards for Information Integration and Control of ECSs based on RESs over IP-based Networks
Authors: S. Jaloudi  , A. Schmelter  , E. Ortjohann  , W. Sinsukthavorn  , N. Alamin  , P. Wirasanti  , D. Morton
Published: May 2017

Energy converting systems (ECSs) based on renewable energy sources (RESs) are penetrating rapidly in the power system including their associated software and hardware (SW/HW) systems. These systems are geographically dispersed, and related to different manufacturers. Therefore, the future power system can be considered as a distributed SW/HW system. Information integration and interoperability are two serious problems in distributed systems, which mainly include communication networks and communication protocols. The International Electrotechnical Committee (IEC) standards are proposed for this purpose and for the control as well. Indeed, some of these standard protocols can be used over IP-based WANs. However, future power systems, which contain many RESs in all voltage levels, could employ the Internet/Intranet WAN for both control and telemeter. This paper investigates the available standards related to power systems, discusses the possibility of applying some of these standard protocols for the control and telemeter of ECSs over Internet/Intranet WAN, compares between two legacy standard protocols and presents the factors for choosing the right protocol for such purposes. In addition, it covers the gaps, the last advances and projects related to these standards.
A Modified Cooling System for Stand Alone PV Greenhouse in Remote Areas
Authors: N. M. Ahmed  , H. M. Farghally  , F. H. Fahmy  ,  A. A. Nafeh
Published: May 2017

Agricultural efforts are normally carried out in remote areas where electricity from national electric grid may not exist or grid connection is very expensive. Greenhouses industry is one of the most important agricultural practices in remote areas. Greenhouses help in extending the gardening activities and allows us to cultivate certain plants all over the year; by controlling air temperature and relative humidity inside greenhouse. In greenhouses, cooling and pumping equipments dominate the demand for electricity. Therefore, a stand-alone photovoltaic (PV) system is necessary to feed that demand. Medicinal herbs, for example are the most suitable plants to be cultivated in the greenhouses. They often need a temperature range of 15 - 21 oC and about 70% relative humidity to grow. As the climate in Egypt is not suitable all over the year to cultivate these medicinal herbs, it is preferable and necessary to use PV-based control greenhouse to cultivate these medicinal herbs in Egyptian remote areas. This paper presents a proposed greenhouse cooling system, which uses a stand-alone PV system to feed the electrical loads of the greenhouse. At the same time, it introduces the complete sizing procedure of the greenhouse stand-alone PV system.
A viable megawatt-class space power installation under the Rankine cycle
Authors: R. Ferreiro Garcia
Published: May 2017

The aim of the article concerns to the description of the main achieved research results regarding the viability of a megawatt class space power plant based on the Rankine cycle. The main objectives are to find the key issues to improve the Rankine cycle efficiency. With the proposed modifications, the ideal thermal efficiency achieved using the proposed strategies increases significantly with respect to conventional power plants. This benefit associated to the reduction of the required payload capacity, reduction of the condenser radiation surface and reduction of the power plant or installation weigh; represent the main advantages of the proposed technique
IDENTIFICATION OF THE REFRIGERANT PRESSURE IN SPLIT-TYPE AIR CONDITIONERS BASED ON HARMONIC ANALYSES OF ELECTRICITY SUPPLY CURRENT
Authors: Zeljko Djurisic  , Milenko Djuric
Published: May 2017

An analysis is presented of the interdependence between power supply characteristics of single phase split-type air conditioners and pressure of the operating fluid (refrigerant) within the air conditioner system. On the basis of the tests performed by a real air conditioner the corresponding correlations have been established. Of special interest is the influence of refrigerant pressure on the level of the second harmonic of the supply current and active input power of air conditioner. The established correlations allow that by processing the input current and voltage of an air conditioner one can make a diagnosis of the state of refrigerant pressure within the system which is a fast, comfortable, and ecologically better approach compared to the classic direct measurement on the operating fluid by a pressure gauge.
Effects of non-zero phase harmonics on inductions machines and coupled mechanical loads
Authors: Filipe Oliveira  , Gerardo Peláez  , Manuel P. Donsión  , J. Iwaszkiewicz  , J. Perz
Published: May 2017

The presence and effect of harmonics in power systems is widely known, but some of its effects are still only partially studied and addressed in existing works. Traditionally, power system harmonics were nearly always not phase-shifted from the fundamental sine wave, and therefore the effect of the phase was not considered. This paper will address the influence of such harmonic content, with non-zero phase, in the behaviour of an induction machine and its mechanical load, namely in mechanical vibrations produced and speed stability. While mechanical vibrations are intrinsically present on rotating machines, both electrical and mechanical parameters can have a strong influence in their severity. This being a broad topic of research, this paper intends to show a preliminary approach destined to validate some of the starting points set for the development of further work.
Reliability and Predictions of Power Supplied by Wind Power Plants
Authors: Z. Hradílek  , T. Šumbera
Published: May 2017

The paper deals with the reliability analysis of electrical power supplies from renewable sources. It focuses primarily on wind power stations which provide variable, stochastic power supply to the distribution and transmission network. Results from application of wind power plant power flow measurement methodology are shown in this paper. We apply measurement methodology to two wind power plants in different localities and we analyze measured values. In the last part is a description of the prediction model developed at the Technical University of Ostrava
Power Quality measurements near DER and disturbing loads
Authors: M. van Lumig  , S. Bhattacharyya  , J.F.G. Cobben  , W.L. Kling
Published: May 2017

This paper describes the results of a four years (2006-2010) Power Quality (PQ) monitoring campaign conducted in the Dutch networks. Purpose is to get insight in the PQ at the point of connection (POC) of some connected customers with typical characteristics as for example distributed energy resources (DER) and to compare these results with the limits given in the EN50160. The results show however no specific problems near a large amount of photo voltaic (PV) panels. There was no correlation found between the harmonic distortion of the grid voltage and the production of solar energy. Pst levels are slightly higher on semi-cloudy days, but due to the low grid impedance never exceed the standard limits. Also near wind turbines no problems with the PQ are visible. The PQ near disturbing loads, like variable speed drives (VSDs), shows higher 5th and 7th order harmonics on MV level. Overall, because of the usually strong Dutch grids, no PQ problems were measured at the specific locations.
Smart meter based energy management system
Authors: Dr. Péter Kádár
Published: May 2017

The number of smart meters reached over 40 millions in Europe
at the end of 20081 . Far beyond the simple energy metering,
these devices enable companies to inform the customers, to
control the load and to increase the energy consciousness.
The standardisation of the smart functionalities is in progress.
The households for lack of knowledge and information do not
care for the energy retrenchment.
New central software applications have been developed that can
perform remote energy management functions through
communication to the distributed smart meters (specific value
calculation, trend monitoring, limit violation alarm, etc.). The
paper gives an overview about the existing remote energy
management systems and makes recommendations which
functions would be useful in the Hungarian environment, too.
Is it economically possible repowering Wind Farms. A general analysis in Spain
Authors: L. Castro  , A. Filgueira  , Mª A. Seijo  , E. Muñoz  , L. Piegiari
Published: May 2017

- Protecting the environment is becoming a major concern; people are beginning to realise that their living conditions may worsen if they do not rationalise energy use and habits. Environmental pollution and emissions from greenhouse gases caused by fossil fuel use are a threat to sustainable development. With renewable energy sources, no polluting emissions are released into the atmosphere. Therefore, using these sources on a large-scale is a key to reducing emissions and meeting the commitments established by the Kyoto Protocol. At the same time, renewable energy contributes to sustainable development. This study describes economic aspects of the repowering process for the wind farms. This process was the result of a growing demand for renewable energies, facilitated by the great potential of wind energy in the north of Spain. The wind farms studied in this work were set up before 1998 and they have obsolete machinery with low power.
Comparative study of Biodiesel Production from Ethanol and Babassu oil using Mechanical Agitation and Ultrasounds
Authors: Eduardo J. Mendes de Paiva  , Jayne Carlos S. Barboza  , Maria Lucia Caetano Pinto da Silva  , Heizir Ferreira de Castro  , Domingos Sávio Giordani
Published: May 2017

Babassu oil is a vegetable oil extracted from the
seeds of the babassu palm (Attalea speciosa), which grows in
most areas of South America. Brazil is the world's largest
exporter of ethanol; the advantages of this alcohol are concerned
to its renewable origin and low toxicity. In this work ethyl esters
of babassu oil were synthesized by alkaline catalysis in
homogeneous medium. The experimental design was used as a
tool for optimization of the transesterification reaction and also in
identifying key factors influencing the conversion into ethyl
esters. The transesterification reactions were performed using
two methods - the traditional mechanical agitation and agitation
promoted by ultrasound waves. The nuclear magnetic resonance
spectroscopy was used to quantify the conversion of all reactions
of transesterification. According to the model obtained for
mechanical agitation, conversions above 99% are obtained when
the stoichiometric ratio is set at 6:1, with 1.0% KOH, under
stirring at 400 rpm, in 60 minutes. Alkaline transesterification
assisted by ultrasound waves produced the best results with
respect to time of reaction and phase separation of glycerin and
ethyl esters. The experimental model showed that conversions
above 99% can be obtained in 10 minutes after adjusting the
other independent variables.
Proposal for Development of a Fragmented Mobile Substation for Treatment of Seasonal Loads
Authors: Arnulfo Barroso de Vasconcellos  , Dr.; Jéssica Romeiro de Carvalho  , Marina Silva Camillo de Carvalho  , Marllon Welter Schlischting  , Teresa Irene Ribeiro de  Carvalho Malheiro  , Luciano Vogel Dutra  , Wagner Gentil
Published: May 2017

Currently existing mobile substations in the market are characterized by a unique set involving protection, switches, transformer and others. This set has considerable weight and size, making it difficult to trafficability and mobility, due to limitations imposed by DNIT, besides the size and characteristics of the road network in the state of Mato Grosso. This article discusses a concept of fragmented mobile substation modules. This new proposal will provide a faster service by avoiding monetary penalties by indicators of continuity, and diversity into emergency care, as well as in meeting seasonal peak demands of certain regions of the Mato Grosso due to the characteristics of industries that comprise the agribusiness. This article addresses some additional advantages in the use of vegetable oils as compared to mineral oil. The use of vegetable oil as well as presenting technical advantages reduces possible harm to the environment during the displacement of the mobile substation.
The road to nearly zero energy buildings. Case of study: Spain. Comparison between CTE HE 2006 and 2013 in a simulated model
Authors: D. Carmona  , D. De La Maya  , A. García  , L.A. Horrillo  , A.M. Reyes
Published: May 2017

Achieving Nearly Zero-Energy Buildings (NZEBs) is a main goal for the European Union, in order to reduce energy consumption in the building sector. NZEB means a building that has a very high energy performance. Its energy requirements should be covered by renewable sources, produced on-site or nearby [1]. It could be possible if building were turned into a “small power generating station”, or reducing consumption with passive building proposals. However, we think that it is worth looking for a balance between energy consumption and generation for every building, following this simple equation: Consumption = demand – generation The European regulations have already begun to indicate deadlines to implement NZEB requirements in buildings. Therefore, Spanish legislation related to energy efficiency and renewable energy generation in buildings has been recently updated, CTE HE [2]. This paper provides a comparative analysis for the new requirements (2013 CTE DB HE compared with previous 2006 regulation, revised in 2009). This study was performed by using a computer building model, including its geometry, building materials, usage profiles and installations. Thus, we could compare the characteristics of the different regulations, and we could evaluate the progress toward the NZEB concept.
A fault detection method for pitch actuators faults in wind turbines
Authors: C. Tutiv´en  , Y. Vidal  , L. Acho  , J. Rodellar
Published: May 2017

The paper presents a model-based fault detection method for pitch actuators faults using the normalized gradient method to estimate the parameters of the pitch actuator. One major difficulty is that the input signal to the parametric estimation method must be a persistent excitation. To circumvent this, a chattering term is added to the pitch control law and the usual low-pass filters are not used for the parametrization in the normalized gradient method (thus acceleration information is used). In order to verify the proposed method, simulations are conducted within a Hardware in the Loop (HiL) platform using the wind turbine simulation software FAST (Fatigue, Aerodynamics, Structures, and Turbulence).
Increase of Voltage Quality in Industrial Distribution Systems
Authors: M. Cernan  , Z. Muller  , J. Tlusty
Published: May 2017

This paper deals with the solution of the issue of exceeding the permissible levels for long-term flicker effect Plt in industrial distribution systems. Flicker effect in distribution systems is often exceeded as a result of the connection of electric arc furnaces, which exhibits high variable electrical power in-take. The article shows the benefits of measures on the steel plants, the distribution system operator and the transmission system operator. The main benefits were the installation SVC device and reconstruction of substation 220/110 kV to substation 400/110 kV. Measurements have shown that the flicker has a major impact and configuration system 110 kV. In some cases, exceeded values flicker effect, and therefore the final part of the article deals with the possibility of deployment of active filters low power.
Metaheuristic approach to the Holt-Winters optimal short term load forecast
Authors: E.Eusébio  , C. Camus  , C. Curvelo
Published: May 2017

Electricity short-term load forecast is very important for the operation of power systems. In this work a classical exponential smoothing model, the Holt-Winters with double seasonality was used to test for accurate predictions applied to the Portuguese demand time series. Some metaheuristic algorithms for the optimal selection of the smoothing parameters of the Holt-Winters forecast function were used and the results after testing in the time series showed little differences among methods, so the use of the simple local search algorithms is recommended as they are easier to implement.
Control of Battery Energy Storage System for Wind Turbine based on DFIG during Symmetrical Grid Fault
Authors: T. Riouch  , R. EL-Bachtiri  , A. Alamery  , C. Nichita
Published: May 2017

This paper presents a specific control strategy of Doubly Fed Induction Generator (DFIG) conceived for a wind turbine system operating under electrical grid disturbance. Two mains aspects related to DFIG behavior are studied: fluctuation of its output power and Low-Voltage Ride Trough capability (LVRT) of wind turbine generator system. In order to smooth the output power injected in the electrical grid and to improve dynamic behavior of a variable speed wind turbine generator system under symmetrical voltage dip, a control strategy of the Battery Energy Storage System (BESS) is proposed. Simulations have been carried out in Matlab environment, and the results validate the effectiveness of our control.
Different LC power filter topologies - effectiveness of reducing voltage distortion
Authors: Chamberlin Stéphane Azebaze Mboving  , Zbigniew Hanzelka  , Andrzej Mondzik
Published: May 2017

This Paper aims to present a comparative study of different passive filter configurations. Five topologies of passive RLC filters for the purpose of the mitigation of harmonics voltage distortion are considered. Basis for evaluating the effectiveness of different filter topologies are simulation and laboratory studies.
Smart switchboards positioning in microgrids
Authors: A. Vianna  , R. Souza  , R. Calili
Published: May 2017

this work develops an approach to smart switchboards allocation in industrial plants and microgrids aimed at optimizing the cost of electric cables. A case study is presented where the proposed methodology is applied and the results are compared with the actual data extracted from a conventional design to the same plant without using any smart technique for allocation of the switchboard. The cost savings are significant and extend to CO2 emissions.
Multi-Objective Optimal Operation Considering Voltage Stability for Unit Commitment
Authors: Masahiro Furukakoi  , Tomonobu Senjyu  , Toshihisa Funabashi
Published: May 2017

Nowadays renewable energy is becoming very familiar by providing a lot of benefits in the power system as well as environment. However, renewable generations like Photovoltaic (PV), Wind generation (WG) output power depends on the weather conditions that causes power generation uncertainly because changing weather condition determines the output power of the renewables generation. As we know, most of electric power companies have been introduced renewable energy that will increase the power system uncertainty simply. Therefore, it is predicted that this uncertainty will increase the likelihood of voltage instability and voltage collapse. On the other hand, renewable energies have great contribution to save power producer from completion by reducing per unit operation cost. Electric unity company requires to an optimal operation to maximize the profit that is why Unit Commitment (UC) becomes an important issue in recent decade. Also, fluctuations in supply and demand are increased by the introduction of renewable energy. Thus, we suggest the optimal operation method of the generator and the energy storage for Unit Commitment by considering the voltage stability in this research. Besides, a battery storage system has been proposed by using this devices, the power fluctuation can be reduced. The effectiveness of the proposed method is verified by simulation results in the Matlab/simulink.
Voltage stability improvement of power system using a shunt capacitor
Authors: Masahiro Furukakoi  , Tomonobu Senjyu  , Toshihisa Funabashi
Published: May 2017

Due to the deregulation of the electricity market, increasing demand approaching transmission capacity, and the endeavor for economic benefits, the power system is recently placed under more severe operating conditions than ever before. Therefore, voltage stability analysis is a major concern in power system planning and operation. This paper proposes a method to improve the voltage stability of the power system by using the active and reactive power information of the transmission line in accordance with the voltage stability index. Installing a bank of shunt capacitors at the load substation in order to inject the proper amount of reactive power can improve the voltage stability of the system as shown by simulations.
Short-term load forecasting using an Artificial Neural Network for Battery Energy Storage System
Authors: Hyang-A Park  , Suel-Ki Kim  , Jong-yul Kim  , Jin-Wook Kim  , Kyeng-Hee Cho  , Eung-Sang Kim
Published: May 2017

Load levelling that use recent spotlighted the Battery Energy Storage System (BESS) saves spare electricity or low cost electricity. The saved electricity can be used for peak power demand time. In this paper, load is predicted for purpose of operating the BESS effectively. By analysing pattern of industrial load, it is classified into workdays, Saturday and holidays. Then apply ANN on workdays load pattern from classified load patterns to predict load. To increase accuracy, number of neurons in hidden layer and learning data period are changed for estimation of load. After that, error rate was calculated for comparison and analysis.
Analysis of the oxygen scattering behaviour on ionomer surface in catalyst layer of PEFC
Authors: Masataka Nakauchi  , Takuya Mabuchi  , Ikuya Kinefuchi  , Hideki Takeuchi  , Takashi Tokumasu
Published: May 2017

Mass transport significantly affects the reaction efficiency of polymer electrolyte fuel cells. In particular, the oxygen transport in catalyst layers is important for the improvement of its efficiency. However, the mechanism of oxygen scattering on ionomer surface, which is one of the dominant factors of transport phenomena, has not been clarified. Therefore, we analyzed the oxygen scattering behaviour on ionomer surface using molecular dynamics simulation. Oxygen molecules are impinged to ionomer surface with different incident energies and angles. According to the total energy of oxygen molecule, the trajectories of oxygen molecules are classified into trapping or scattering. The trapping probability of oxygen molecule on ionomer surface decreases as the normal component of the incident energy increases. Oxygen molecules with low normal incident energy get energy during the gas–surface interaction on the surface and desorb from the surface. The number of collisions with the surface does not affect the energy transfer between oxygen molecule and ionomer surface.
Decentralized control techniques for plug-in electric vehicles in MV/LV distribution networks
Authors: J. García-Villalobos  , I. Zamora  , I. Junquera  , J.I. San Martín  , P. Eguía
Published: May 2017

Decentralized control techniques are acquiring more and more importance to efficiently manage a large number of distributed energy resources (DER). It is expected that, in the future, plug-in electric vehicles (PEVs) will act as DERs providing valued services to power grids. In addition, it has been proven that uncontrolled charging of PEVs will have a significant impact on the operation of MV/LV distribution networks. In this context, this paper presents a review on decentralized control approaches to adequately integrate PEVs in MV/LV distribution networks. Among these decentralized control techniques, optimal and droop based controls are the most common. Both have strengths and weaknesses, so, more research about mixing both methods is needed.
Optimal Design and Operation of a PEMFC-based CHP System Connected to Grid
Authors: F.J. Asensio  , J.I. San Martín  , I. Zamora  , J. García-Villalobos  , Pablo Eguía
Published: May 2017

This paper is focused on the optimal design and operation of a Combined Heat and Power (CHP) system based on Proton Exchange Membrane Fuel Cell (PEMFC) connected to grid, whose aim is to supply the energy requirements of the Educational Complex of the Engineering School of Eibar - University of the Basque Country (UPV / EHU). To achieve the optimal design and operation of the system, the PEMFC-based CHP system has been simulated on the base of each of the proposed schemes and operation strategies, and a detailed analysis of the results obtained has been conducted, which has allowed to choose as optimal, the design that has better maximized the economic-energetic efficiency of the whole system, and has been adjusted better to the viability criteria established.
Madrid biocity: biomass and bioenergy potential
Authors: J.P. Paredes-Sánchez
Published: May 2017

Fossil fuels such as oil, coal and natural gas represent the prime energy sources in the world. Large amounts of solid biomass are currently produced and used in the EU. Biomass energy is expected to make an important contribution to the energy and environmental objectives. Biocity is a new concept; it is a city that uses its own available biomass resources in a sustainable manner for energy purposes. Based on BIORAISE GIS software for the assessment, an analysis of biomass and bioenergy were evaluated. This paper studies the available bioenergy to develop a stable biomass feedstock from the woodland and cropland residues for thermal purposes in a city. A case study is applied in Madrid. The result shows 228 dry kt/year equivalent to 3,890 TJ/year as an energy resource.
Biomass supply to a coal power plant under sustainable development conditions
Authors: J.P. Paredes-Sánchez
Published: May 2017

Nowadays, biomass residues of wood forests have no specific application in many areas of the world. Wood forest can be a bioenergy supplier to substitute the use of fossil fuel. The forest area owns residues when the cleaning is not carried out in a periodic way, mainly because the management of residue is very complicated as a consequence of the orography. This work aims to improve existing methods and develop new ones for evaluation and utilization of forest wood residue from cleaning and thinning in accordance with the safety and environmental requirements of the biomass feedstock in a coal power plant for a sustainable industry. This implies an analysis of both the resources and the existing limitations for a proper valuation considering technical and environmental restrictions. The potential forest residues existing in the studied area can contribute to reduce the fossil fuel dependence. The potential feedstock for the coal power plant is 90 dry kt/year, which is equivalent to 24 MWe and generates 165 kt/year of CO2 neutral emissions.
A hybrid solar panel maximum power point search method that uses light and temperature sensors in real shading conditions
Authors: J. Mroczka  , M. Ostrowski
Published: May 2017

Solar panels are common renewable energy sources. They generate electrical energy directly from the solar energy but have low efficiency and non-linear characteristics. To decrease the power loss solar panels are connected to special devices called maximum power point (MPP) trackers. When the surface of the solar panel is illuminated irregularly in the power voltage curve can be observe the appearance of the local maximum power points that are different from the global maximum power point. In the partial shading condition the regular trackers can track the local maximum power point. The presented method use the light and temperature measurement to determine the global maximum power point. The simulation results prove correctness of proposed method in real shading conditions. The proposed algorithm has high tracking speed and does not depend of used solar panels, and by that can be used in any solar system.
Numerical study of the cooling capacity of several alternative liquids in zig-zag cooling system of a power transformer
Authors: Agustín Santisteban  , Fernando Delgado  , Alfredo Ortiz  , Inmaculada Fernandez  , Carlos J. Renedo
Published: May 2017

Mineral oil is the usual coolant of the power Transformers. Nonetheless, the high risk of fire of this liquid due to its low ignition point and its scarce biodegradability has promoted the development of dielectrics alternative fluids with better physical-chemical properties. However, these new liquids have to be as good coolants as mineral oil in order to maintain the power transformer performance. This numerical study analyzes the coolant capacity of some of these new commercial liquids (a natural ester, a synthetic ester, and a silicone oil) by using the zig-zag cooling system of the low voltage winding of a real power transformer. Two types of thermal-fluid studies (parametric and time-dependent studies) have been made by using a 3D model of this system. The comparison of temperatures obtained from the parametric study (different inlet flow rates) allow us to say that the worst coolant is the silicone oil. Also, it can be say that a significant increase in the inlet flow rate produces mild drops of hot-spots temperatures and no modification in the initial temperature distribution. For the time dependent study (25% of overload during 1 hour), the hot-spot temperature exceed the limits, which negatively affects the aging speed of the insulating paper and therefore the transformer lifetime.
A Generalized Coverage Matrix Method for Power Quality Monitor Allocation Utilizing Genetic Algorithm
Authors: D. P. S. Gomes  , M. Oleskovicz  , T. R. Kempner  , J. R. Lima Filho
Published: May 2017

With the increase of sensitive loads and, in many cases, causing disturbances in distribution systems, power quality monitor allocation has become a subject with increasingly importance. Therefore, it becomes necessary to have well-formed strategies to allocate such equipment, since they have high cost that needs to be minimized. With this objective, this research provides a methodology for monitor’s allocation that seeks to minimize the amount of equipment needed to observe voltage sags in distribution systems. The developed methodology is based on the fault voltage matrix, to obtain the residual voltage during faults, on the coverage matrix and the application of a genetic algorithm as optimization tool. The research also brings as contribution, changes in traditional methodology to better represent the indicated phenomena in distribution systems and to give better support to fault location studies, justifying a development of a generalized coverage matrix. To test this methodology, the IEEE 34-node test feeder was utilized with promising results reported and commented further.
Self-tuning Kalman filter and machine learning algorithms for voltage dips upstream or downstream origin detection
Authors: H. Shadmehr  , R. Chiumeo  , L. Tenti
Published: May 2017

In this paper, self-tuning Kalman Filter (KF) is applied to a significant sample of full waveforms associated to the voltage dips monitored in the Italian distribution network by the QuEEN system, with the aim of events detection and waveforms segmentation. Segmentation is done in order to extract more features and information from the original voltage waveforms, to make easier voltage dips classification, based on the events source location (upstream/downstream from the point of measurement). The aforementioned classification is achieved by Machine Learning algorithms. The evaluation of the obtained results is based on the computation of a “confusion matrix”.
Potential Application of Hybrid Renewable Energy Systems in Aquafarms of Veracruz, Mexico
Authors: F.J. Gómez  , I. Valencia  , A. Pérez-Navarro
Published: May 2017

This paper reviews the existing legal framework in Mexico to promote the use of renewable energy in aquaculture activities. An analysis of the potential of renewable energy available in the state of Veracruz is also made, such as wind, solar and biomass, in order to determine its feasibility in the design of hybrid renewable energy systems (HRES) applied to aquafarms in the central coastal region central of such state. It was found that SAGARPA (Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación) has a specific program for the implementation of renewable energy in the agricultural sector. Moreover, the possible application of HRES in aquafarms of Veracruz is feasible and recommended for reduction in costs relative to energy consumption.
Development of a System for the Usability of Forest Residues for Electric Energy Production
Authors: S. Baranovschi  , A. Roque  , D. Sousa  , V. Fernão Pires
Published: May 2017

Forest residue mass from timber harvests is a renewable resource that can be used for electrical utility production. Under this context, this work presents the development of a system for harnessing forest residues. The system consists in several different parts, constituting a complex mechanical-hydraulic-electrical coupling system. With the development of this system, forest residues and derivatives can be used through thermoelectric plants to produce electric energy. In this paper, the proposed system, due to its specific structure, supports a wider range of forest residues that can be processed, i.e., mixed residues of different sizes and shapes can be used simultaneously. In addition, this solution may allow to skip pre processing fragmentation.
Reverse supply of an AC distribution feeder through a Medium Voltage DC link
Authors: F. Belloni  , R. Chiumeo  , C. Gandolfi  , D. Palladini  , A. Villa
Published: May 2017

Medium Voltage Direct Current grids seems a promising solution for meshing AC grids, in order to enhance their distributed generators hosting capacity. The DC link is created through power electronics interface converters, which allow implementing different functions through suited control strategies. In particular, the paper investigate the possibility of supplying AC connected loads in island operation, i.e. separated from the mains, when a fault occurs in one of the AC grids. A 5 MW link is considered in the paper. Relevant power converters has been designed and modelled in a digital simulation environment. A complex control strategy for the management of the complete process of island supply and reconnection to mains, involving also communication between converters and grid protections, has been implemented and tested through simulations. Simulation results confirms the effectiveness of the proposed approach.
Voltage/load Control Strategy for Smart Distribution Grids with a High Penetration of Renewable Energy Sources
Authors: NourEldeen Elsayad  , Khaled Bashir Shaban  , Ahmad Massoud  , Ramadan ElShatshat
Published: May 2017

The exponential increase of renewable energy sources (RESs) penetration in the power grid introduces the of voltage instability when RESs are integrated into medium and low voltage networks. This paper proposes a state-machine based voltage/load control strategy for different operating scenarios in a system comprised of a large RES power plant connected to a medium voltage bus at 11kV, and small RES systems scattered across low voltage networks at 415V. Three modes of operation are summarized, in which the appropriate action is taken according to the availability of RES power generation in the network and the loading condition of this network. Efficient power sharing is achieved via the utilization of a communication network deployed between the RES systems. The communication protocol of the network is represented in four messages adopted by the RES systems integrated into the grid. The effectiveness of the proposed voltage/load control strategy to surpass overvoltage cases caused by over-generation of RES power is illustrated through simulations. The proposed strategy can be adopted by either agreement between a utility and RES owners, or by making it the basis for a standard for RES installation.
A NEW DESIGN METHODOLOGY OF A SWITCHED RELUCTANCE GENERATOR CONSIDERING THE INFLUENCE OF THE MUTUAL INDUCTANCES
Authors: Dias, R. J.  , Reátegui, C.  , Costa, C. S.  , Fleury, A.  , Andrade, D.A.  , Cardoso, H.C.  , NERIS,  N.M.  , DOS SANTOS, B.R.
Published: May 2017

The subject of this paper is to present the design of a Switched Reluctance Generator (SRG) taking into account the presence of mutual inductance, which has been ignored in the literature of switched reluctance machine (SRM). A step-by-step for the mechanical and electrical magnitudes sizing is demonstrated, both for prototype construction and for graphic representation in CAD software. Thus, with the drawing of SRM lamination plate, the mutual inductance is measured trough a finite element software called FEMM (Finite Element Method Magnetics), whose values are processed and arranged in inductance matrices with the aid of MATLAB®. Once with inductance matrices, the mathematical modeling is implemented on SIMULINK MATLAB® and the results are presented. Finally a SRG prototype is constructed to validate the design proposed here.
Drawbacks of a medium sized, grid coupled Photo Voltaic Array
Authors: C. Keyer  , I. Setiawan  , F. Leferink
Published: May 2017

A medium sized photo voltaic (PV) array with good inverters produces high quality, real (true) power.. The maximum allowable reactive power is a percentage of the real power consumed from the grid. Before the PV array was installed the reactive power was less than 50% of the real power, which is allowed by the by-laws. Because of the amount of PV generated real power the actual consumed real power reduced. The ratio of reactive power to the consumed power changed therefore drastically. According the by-laws and the utility the eactive power drawn from the power grid is too high and the owner of the PV installation now has to pay a fine.
A Power Take-Off and Control Strategy in a Test Wave Energy Converter for a Moderate Wave Climate
Authors: K. L. De Koker  , G. Crevecoeur  , B. Meersman  , M. Vantorre  , L. Vandevelde
Published: May 2017

The energy in the waves of oceans and seas can be converted to electricity by different types of Wave Energy Converters (WECs). Wave energy conversion is currently widely studied to contribute to the world’s rising energy needs. This paper describes a point absorber test WEC that was built for electrical energy production in moderate wave climates as can be found in the Belgian part of the North Sea. A robust design was put forward to assess the feasibility of a full electric rotational Power Take-Off (PTO) system. A stable reactive control algorithm was implemented to optimise the absorbed energy from the waves by tuning the natural frequency of the WEC towards the frequency of the waves. From simulations it is shown that also for real irregular waves, this tuning shows a significant beneficial effect on the absorbed energy. The control parameters for different wave conditions are discussed as well as the effect of the chosen PTO system and its constraints on the absorbed power and optimum control parameters.
Radiation Performance of a Cavity Receiver for a Parabolic Dish Solar Concentrator System
Authors: O. López  , A. Arenas  , A. Baños
Published: May 2017

The radiation performance of a modified cavity receiver for a low-cost concentrating solar power plant is studied. The optical phenomenon taking place is modelled by using a ray tracing technique based on a finite element approach. This design is also compared to a flat receiver. Corrections for sunlight and optical errors of the parabolic dish are included. Its efficiency is analysed by varying some geometrical parameters of the receiver, maximizing the total power absorbed. It is found that the flux density on the cavity walls is less than on the flat receiver walls, hence decreasing heat losses. Also, in order to reach a maximum radiation performance the receiver is to be placed closer to the concentrator from the focal position. However, the aperture does not improve notably its efficiency, although it has an important role in the convection heat losses as shown in previous works. Finally by varying the cavity diameter it is possible to improve the efficiency when it is well adjusted to the radiation performance of the concentrator on the focal point.
Analysis of Cell to Cell Voltage Variations in a 4-cell and 25- Cell Low Temperature PEM Stacks
Authors: Etim U Ubong  , Kishore Asokan  , Uwem U. Ubong  , Ini U. Ubong
Published: May 2017

An experimental study of cell to cell voltage variations on two different low temperature (LT) PEM stacks is presented. One is a‐4 cell‐membrane‐humidified stack. The second is a‐25 cell stack with an external humidifier. The test results taken from open circuit voltage to full load reveal that in both stacks, the first cell almost always produced the least voltage. Further tests at additional two levels of air stoichiometry (Sair) with the 4‐cell stack confirmed the previous observations. An analysis is conducted to unravel the influence of various factors on cell to cell voltage variations. Limitations of this investigation are noted and future work is suggested.
Analysis of Power Generation and Transmission from Very Large-Scale Photovoltaic Systems in Algeria
Authors: S. Flazi  , A. Boudghene Stambouli  , M. Bouzid
Published: May 2017

In addition to the well-recognised two values of vast land and sunshine of Algeria, its Sahara desert has the third value, energy production and export. Subsequently, Algeria can then become a role model to other countries in the world that has huge solar and energy feedstock. In this article, a particular attention is being given to the Algerian Sahara in terms of solar potential capability in that it could capture enough solar energy to meet the total energy needs for sustainable development of Algeria, Sahara cultivation and Repopulation and electricity Export to Europe using Very Large Scale- Photovoltaic (VLS-PV) system. Moreover, the article is also concerned with studying the energy transmission losses from the generation site, in depth Sahara of the south of the country, to the north as well to European countries. A rough calculation of the Losses was made for a transmission overhead line of 400 kV three-phases, 1000 MVA using ALMELEC cable of 1600 mm2. The calculated losses results were found to be 15% per 1000 km. The optimal location to start the installation of VLS PV systems is proposed.
Real Time Simulation of HVDC and VSC-HVDC models: Application to Algerian – Spanish Power System Interconnection
Authors: M.Khiat  , L. Ghomri
Published: May 2017

Most of world’s electric power systems are now widely interconnected involving inter-regional and international connections. The purpose is to achieve better efficiency in generation and transmission of energy. We need these interconnections to take advantage of diversity of loads, availability of sources and fuel price to supply electricity at minimum cost with a required reliability. In addition to the existing interconnections, namely those of the Maghreb, Algeria is Already interconnected to Tunisia (4 connections) and to Morocco (2 connections). But a direct interconnection with European countries around Mediterranean Sea will be open up new opportunities to both partners for economic and technical reasons. Since 2002, Algeria has a new politic to diversify international exchanges. A great number of studies of Interconnection Algerian-Spanish network project have been done by many organisations. Furthermore with the HVDC and VSC-HVDC technology, who allowed DC transport, this interconnection, can be achieved with high reliability. But there is the constraint that Maghreb countries networks are weak in comparison with Spanish one which is robust, and strongly interconnected with European network. In order to give some elements of solution to realise this project, real time simulators of grids are an interesting tool. These simulators are used to simulate grids and electrical equipments with input/output signals to interact with real equipment. In this article, we present different HVDC and VSC-HVDC models, and we will define the best adaptive one to real time simulation, and results obtained with EMEGASIM of the RT LAB platform.
O percurso dos Estudos Clássicos no Brasil
Authors: Cardoso Zelia de Almeida
Published: May 2017

Este artigo tem o objetivo de explorar o trajeto dos estudos clássicos no Brasil focalizando a educação jesu­ítica, as academias literárias do século XVIII, a literatura do período arcádico, o papel do teatro na divulgação da cultura clássica, a organização dos programas da educação secundária e, finalmente, a criação das Faculdades de Letras e das socieda­des científicas que se ocupam da Antiguidade clássica.
Abordagens mitológicas na iconografia funerária da cerâmica ática (510-450 A.C.): repensando a periodização
Authors: Cerqueira Fábio Vergara
Published: May 2017

Este artigo tem por objetivo estudar a iconogra­fia funerária registrada sobre a cerâmica ática, e, em especial, a produção do que chamamos fase intermediária (510 – 450a.C.), que tem despertado menos atenção dos estudiosos, mais voltados à compreensão do período anterior, dos alabas­tros e lutróforos de figuras negras do século VI, precipuamen­te com cenas de “velório”, ou do período posterior, dos lécitos brancos prolícromos com cena de visita ao túmulo. Aponto que, através de abordagens mitológicas, de Musas, Sereias e Eros, esta fase, que durou de duas a três gerações de pintores, apresenta uma unidade cultural, no sentido da emergência de visões alternativas da morte, ao retirar a atenção dos rituais da pólis e da família. É neste contexto que se destaca a ico­nografia destes personagens mitológicos, cuja ligação com a música determina a sua ligação com a morte. A ambivalência das Sereias corresponde a uma ambiguidade das concepções de morte que lhes eram relacionadas, oscilando entre uma vi­são ctônica, temível, no mundo inferior, e uma visão celestial, de bem-aventurança, num mundo superior. A “pitagorização” da iconografia das Sereias, como musicistas tocando lýra ou aulós, corresponde a uma expectativa mais positiva do além­-túmulo, sob a proteção das divindades musicais.
Morte de Aemilius Paullus em Cana. Fazendo de herói um general derrotado (Polybius 3.112-117)
Authors: Vendramini Darío N. Sánchez
Published: May 2017

Os estudiosos modernos consideram Políbio uma fonte confiável de informação (por exemplo, WALBANK, 1957, p.16 e LEHMAN, 1967). O principal tema de sua nar­rativa são os acontecimentos políticos e militares que molda­ram a ascensão de Roma ao poder no mundo mediterrâneo; embora apenas porções das suas histórias sobreviveram, a sua superioridade em relação a outras fontes cobrindo este período é geralmente consensual. Em um estudo clássico, E. Marsden analisa Políbio como historiador militar e chegou à conclusão de que era um narrador preciso de eventos militares (MARS­DEN, 1974, p. 270-71). Seu relato da batalha de Canas é um bom exemplo, à medida que considera a descrição do combate melhor do que os relatos de Tito Lívio, assim como outras fon­tes posteriores. A reputação de Políbio como um historiador preciso é bem merecida, e não é o objetivo deste artigo afirmar o contrário. Sua reputação é provavelmente a razão pela qual os historiadores modernos aceitam sua descrição da função de Aemilius Paullus na luta em Canas, apesar de algumas contra­dições e adições fictícias. Na verdade, uma análise detalhada da sua descrição da batalha mostra que o historiador grego, de fato, amplia o enaltecimento de Paullus, e que sua versão das ações do cônsul no campo de batalha deve ser rejeitada.
Amor e alusão à morte: um estudo acerca das representações das heroínas de Ovídio
Authors: Gonçalves Ana Teresa Marques , Medeiros Mariana Carrijo
Published: May 2017

As heroínas construídas por Ovídio, na obra Epis­tulae Heroidum, vivenciam amores extremos, que as levam a pensar na morte como escapatória dos sofrimentos que en­frentam na ausência de seus seres amados. Muitas das perso­nagens representadas por Ovídio prometem cometer suicídio se não conseguirem trazer de volta os heróis ausentes. Neste artigo, objetivamos analisar como o amor e a morte são partes integrantes do pensamento ovidiano expresso nas Heroides.