bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between the genetic hemoglobin polymorphism, morphometry and fertility of Pramenka sheep breed from Central Bosnia
Authors: Vazic Bozo , Rogic Biljana , Drinic Milanka , Przulj Novo
Published: July 2017

The characteristics of these sheep are highlighted depth measures of external
appearance with modest width measures. Another weaker feature of Pramenka
sheep is poor fertility. Despite the mentioned disadvantages, Pramenka sheep
is the most grown sheep in Central Bosnia and sheep production is based on
it. Methodical selection to improve the characteristics of Pramenka sheep
has not applied. However, sheep breeders tend to improve the qualitative and
quantitative characteristics of sheep, and that means more intensive work on
the selection. In this sense, genetic markers are used to carry out the
selection lately. Three types of hemoglobin, HbAA, Hband HbBB of Pramenka
sheep population (at 189 male and female animals) in Central Bosnia were
segregated by the method of electrophoresis. The following genotype
frequencies are determined: HbAA 0.11; Hb0.41; and HbBB 0.48. Allele
frequencies, HbA and HbB for Pramenka sheep breed (estimate based on
genotype frequencies) were 0.315 and 0.685. It was found that the population
of sheep was in the equilibrium of the frequency of hemoglobin genotypes.
Sheep with HbAA genotype had lower morphometric measures in relation to the
other two genotypes. The statistically significant difference between sheep
with Hbgenotype and HbAA genotype was recorded only for the shin
perimeter. The ewes that lambed one lamb have the following frequency of
HbAA, Hband HbBB genotypes: 0.13; 0.40 and 0.47, and the ewes with twins:
0.02; 0.40 and 0.58. Fertility, as important quantitative characteristic of
sheep, was more emphasized in genotype HbBB, than in HbAA genotype. This was
confirmed by the statistical analysis.
Genotype effects on phosphorus, potassium, calcium and magnesium status in maize
Authors: Kovacevic Vlado , Brkic Ivan , Antunovic Manda , Iljkic Dario , Varga Ivana
Published: July 2017

Nine maize lines, commonly used as female parents of maize hybrid (B1=?2-48;
B2=?1767/99; B3=?87-24; B4=?135-88, B5=?84-28; B6=?84-44; B7=?438-95;
B8=?30-8; B9=?B-73) were grown under field conditions on Podgorac acid soil
in Osijek-Baranya County for two growing seasons (2006 and 2007). The
ear-leaves at flowering and grain at maturity were taken from each basic
plot (14 m2) for chemical analysis with inductively coupled plasma atomic
emission spectroscopy (ICP-OES). Average concentrations (2-year means: g
kg-1 in dry matter) were as follows: 3.21 and 3.00 (P), 20.8 and 3.45 (K),
6.60 and 0.05 (Ca), 2.44 and 1.04 (Mg) for leaves and grain, respectively.
Differences among genotypes were from 2.69 to 3.95 and from 2.70 to 3.57
(P), from 18.0 to 23.3 and from 3.03 to 3.71 (K), from 5.45 to 8.02 and from
0.04 to 0.07 (Ca), from 1.35 to 3.09 and from 0.84 to 1.36 (Mg), for leaves
and grain, respectively. Specifies of leaf composition of individual
genotypes were as follows: B1 (the highest Ca and Mg), B2 (the highest P),
B4 (the lowest Ca, Mg and P), B6 (the highest K) and B7 (the lowest K).
Grain composition was mainly in accordance with specifies of leaf
composition. Very high correlation in maize mineral composition under
identical environmental conditions for nine genotypes between two years
(0.97***, 0.97*** and 0.91*** for K, Ca and Mg, respectively) are indication
of high hereditary effects, while P was more under environmental impact (r =
0.43). Significant correlations were found between grain-P and grain-K
(0.55*), grain-Ca (0.49*) and grain-Mg (0.86***), grain-Ca and grain-Mg
(0.54*). However, regarding mineral composition of leaves, only leaf-Ca and
leaf-P had significant correlation (-0.46*).
The lack of correlation between TP53 mutations and gastric cancer: A report from a province of Iran
Authors: Saffari-Chaleshtori Javad , Tabatabaiefar Mohammad-Amin , Ghasemi-Dehkordi Payam , Farokhi Effat , Moradi Mohammad-Taghi , Hashemzadeh-Chaleshtori Morteza
Published: July 2017

Gastric cancer ranks second cause of cancer death worldwide after lung
cancer. Its etiology is heterogeneous and genetic factors including
protooncogenes and tumor suppressor genes always contribute to the
progression of cancer. The TP53 tumor suppressor gene has a broad role in
genomic stability and DNA repair. The aim of this study was to determine the
TP53 gene mutations in gastric cancer specimens in Chaharmahal Va Bakhtiari
province of Iran. In this descriptive-lab based study, we investigated the
promoter and exons of TP53 gene mutations in 38 paraffin-embedded gastric
cancer specimens. DNA was extracted following a standard phenol-chloroform
protocol. The TP53 gene mutations were determined using PCR-SSCP & PCR-RFLP
procedures. The present study revealed no TP53 gene mutation in the promoter
and exons in the gastric cancer subjects studied. While TP53 gene mutations
have been reported as the most frequent genetic alterations and are found in
about 50% of the human malignancies, no mutation was detected in this study.
This may be due to mutations in other related genes in the same pathway or
epigenetic factors.
Genetic diversity analysis in elite lines of tomato (Solanum lycopersicum L.) for growth, yield and quality parameters
Authors: Kaur Simranjit , Jindal Salesh , Dhailwal Major , Chawla Neena , Meena Om
Published: July 2017

To increase productivity in tomato, it is necessary to develop superior
varieties/hybrids. This is, in part, dependent on variability in the genetic
material which affects agro-morphological and biochemical characters in crop
breeding. A study was conducted with 51 tomato genotypes and the standard
checks/reference cultivars Punjab Upma, Punjab Chuhhara and Punjab Ratta to
determine character association, path coefficient analysis and genetic
diversity to select genotypes and traits for breeding. There were differences
among genotypes for all characters indicating a high degree of variability in
the material. Overall, highly significant, positive, correlation
coefficients, as well as high direct effects of fruit weight and marketable
yield on total fruit yield, indicated these traits are reliable components
for selecting high fruit yielding tomato genotypes. The D2 statistics
confirmed the highest inter-cluster distance between clusters VI and VIII
(27638.44). Maximum similarity was observed in clusters IV and VI (191.02).
This indicated existence of the possibility to improve genotypes through
hybridization from any pair of clusters and subsequent selection can be made
from segregant generations.
Metode Penyuluhan Dalam Adopsi Inovasi Inseminasi Buatan (Ib) Pada Usaha Peternakan Sapi Di Kabupaten Dharmasraya
Authors: Ediset Ediset , Jaswandi Jaswandi
Published: July 2017

This  research  was  conducted  in  the  area  Dharmasraya  Regency,  West  Sumatra  Province.  The  purpose  of  this  study determined : a) Method of extention   in innovation adoption of artificial insemination (AI) in the cattle farm in the District Dharamasraya, and b) Social and economic factors that influence adoption of innovation Artificial Insemination (AI) in the cattle farm  in the District Dharmasraya. This research used survey method and approach to the analysis of secondary data. The number of samples in this study were determined by quota sampling technique by reason of homogeneous samples, the farmers were already adopting  innovations  and cattle ranchers IB program participants snapping Birahi Artificial Insemination (GBIB) thus took a sample of 40 people. The data collected were primary data with the help of question naires and secondary data with the literature study and related agencies. Descriptive analysis of quantitative data which was calculated using a Likert scale. The results showed that the extension method in the adoption of IB in cattle breeding business in the Regency Dharmasraya been implemented, namely the extension methods home and farm visits with category, extension methods demonstrations by both categories, and the campaign extension methods with the medium category. Social and economic aspects such as business scale farmers, revenue, risk, active participation in the innovation adoption had no effect on aspects of the IB whereas age despite being influential in the adoption of innovation, but still in the category of less influential.
Household Energy Consumption at an Open Market
Authors: D.M. Larruskain Eskobal  , O. Abarrategui Ranero  , E. Loroño Apraiz  , M. D. Gutiérrez Ochoa de Alda  , F. de la Bodega Bilbao
Published: July 2017

The European directive 2003/53/EC of 26 June 2003 opens the electricity market and settles down that the term limit for all the electricity customers to chose their providing company is 1st July of 2007. Nevertheless, some Member States have gone beyond this term, Spain is among them, from the 1st of January of 2003.
The customers and generators can freely make provision contracts, thus it is necessary to have a system that allows the consumption measurement and the energy transits between the different subjects and electrical activities.
The installation of new measuring equipment in the point of nondomestic qualified customers and network connection is compulsory, although it is not necessary to modify the meters for household customers. But if customers want it, they will be able to install an hour meter, since the consumed energy price has a different hour to hour price in the wholesale market.
Transients in a Wind-mill Driven, Two-speed, Squirrel-cage Induction Generator.
Authors: Jan Rusek
Published: July 2017

The most widespread generator in wind-mill installations is a doubly fed, slip-ring induction generator. The rotor circuit include a static converter allowing power flow in both directions: from the rotor by negative slip and to the rotor by positive slip. However, in small and medium wind power plants a simple, double-speed, squirrel-cage induction generator may be considered as a suitable alternative replacing a doubly-fed slip-ring induction generator. The higher speed range would be predestined for normal operation, which, however, requires some minimum wind speed. If the wind is weaker, re-switching of the generator to the lower speed range would still secure some power output. Re-switching to other speed is, however, accompanied by heavy transients in currents, torque and power. The aim of the contribution is to present the plots of instantaneous speed, torque current, power and voltage by adjusting the operation to strong, moderate and weak wind. The plots of the torque in the clutch may constitute a base for assessment mechanical stress in the gearbox and wind-mill blades.
Reduction of Flicker Effect in Power Plants with Doubly Fed Machines.
Authors: J. Bendl, M. Chomat  , L. Schreier
Published: July 2017

Changes and pulsations in the active and reactive powers generated by wind turbines due to wind speed variations and tower shadow effect may cause serious problems in operation of isolated or distant areas of power grids. Particularly resulting flicker effect may deteriorate power quality in connected power networks. Use of doubly fed machines with suitable control method may substantially reduce impacts of these phenomena. Vector control of doubly fed machines is analyzed and discussed in the paper with respect to the compensation of varying mechanical torque produced by wind turbines. Properties of power units with induction generators and doubly fed machines are compared.
Experimental Behaviour of a Magnetic Field Shield for an Underground Power Line.
Authors: J.R. Riba Ruiz  , X. Alabern Morera
Published: July 2017

This paper describes the experimental behavior of a pure iron magnetic shield for a single-phase underground power line. We have built a 0,5 mm-thick 2 m-long cylindrical shell. The measures realized show that this shield is very effective in order to reduce the magnetic field generated by a single-phase power line placed inside the shield, just in its center.
It is well known that the relative magnetic permeability of ferromagnetic materials decreases sharply when magnetic fields intensities H are very weak (below 0,1 A/m) and when they are very strong (due to saturation phenomena). In these situations the shielding efficiency of these materials is dramatically reduced. This means that the selection of an adequate material to act as a magnetic field is decisive. In order to maximize the absorption losses, such a material must have a high magnetic permeability and a high electric conductivity when dealing with very weak magnetic fields. For these reasons we have selected the purified iron (with a pureness at least 99’95 %).
The ferromagnetic material of the shield (in the studied case is the pure iron) absorbs the magnetic field generated by the buried power line and just a very small portion of the magnetic field survives outside the shield. It is due that as the shield is made pure iron, which has a high electrical conductivity, the induced eddy generate a magnetic field opposed to the magnetic field generated by the power line. Due to the opposed magnetic field, the total magnetic field H outside the shield is reduced.
A New Configuration for Uninterrupted Power in Isolated Locations: Wind Turbine - Electric Generator - Battery Bank (WT-UPS).
Authors: Fernández, H  , Martínez, A  , Guzmán V.  , M. Giménez
Published: July 2017

A new configuration is presented to investigate the use of renewable energy sources, such as wind energy, an auxiliary thermo-electric generator and a battery bank, to feed critical loads in isolated locations in less developed areas, where no electric supply is available. Where possible standard off-the-shelf car parts such as alternators and AVR are used. This configuration, called Wind Turbine Uninterruptible Power Supply (WT-UPS) is a modular system that offers a number of advantages over the classic hybrid systems. Initial experimental results show the system works as predicted.
Two Aplications for Power Quality Analysis using the Matlab Wavelet Toolbox.
Authors: M. J. González-Redondo  , A. Moreno-Muñoz  , J. J. González de la Rosa
Published: July 2017

Nowadays there is an increasing number of electric and electronics equipment that has carried out a growing number of problems that affect to the power quality. Several studies on power quality have been made in order to detect and localise that kind of problems. For such objective it has been used the Wavelet Transform that allows the detection and localisation of disturbances in the voltage waveform. At laboratory level it is possible to use several tools, such as the Matlab Wavelet Toolbox that includes basic commands and a graphic environment. To begin with the study of this tool and its capability in detecting disturbances in the voltage waveform we need several test signals with known disturbances. This paper presents two applications developed for the study of Power Quality based on the Matlab environment.
Generation and Storage of Green Hydrogen and its Application for PEM Fuel Cells.
Authors: J.J. San Martín Díaz  , E. Romero García  , J. Zuazua Ojanguren  , D. Romero García  , V. Aperribay Maiztegui  , J.I. San Martín Díaz  , J.M. Arrieta Albizu  , I. Martín Amundarain
Published: July 2017

The  object  of  this  communication  is  to  show  to  the  application  of  a  new  tool  learning  multimedia  in  which  it  talks  about  the  green  Hydrogen  generation,  that  is  to  say,  the  obtained  one  from  renewable  energies  (in  our  case  of  photovoltaic  origin)  and to their storage, for its later use in the feeding of a standard fuel battery PEM. The  novel  aspect  that  is  tried  to  expose  is  that  the  knowledge  acquired on the part of the user can be resisted by means of the accomplishment of the virtual practices available in the course, cradles by proving stand VENTUS Professional Science.
Perfomance Analysis of Fuel Cells by Modelling.
Authors: I. Zamora  , J.I. San Martín Díaz  , J. Mazón  , S. Díaz  , S. DíazJ.J. San Martín  , J.Mª. Arrieta  , V. Aperribay Maiztegui
Published: July 2017

European Commission energy politics pleads to guarantee electrical energy supply and reduce emissions associated with the climatic change. This requires immediate performances to develop renewable energy sources, alternative fuels for transportation and the increase of the energy efficiency of systems.
In this context, two technologies are attracting to the public and private sectors: the hydrogen, clean energetic vector that can be produced from any primary energy source (mainly wind and photovoltaic energy) and the cell fuels, very efficient devices to convert energy.
This paper presents a revision of the different technologies of fuel cells susceptible of being used to generate electrical energy and cogeneration processes.
Practical Design of a Load Compensation Active Conditioner
Authors: Jaime Prieto  , Patricio Salmerón Revuelta  , Reyes S. Herrera
Published: July 2017

This paper presents the obtained experimental results with a single-phase experimental prototype of a Load Compensation Active Conditioner, sLCAC. The sLCAC is composed by a series – parallel combination of active power filters, and its main objective is the global conditioning of a load against harmonic distortion. On the one hand, to isolate the load voltage vL from the harmonics in the supply voltage vS, as well as to regulate it to the nominal value. On the other hand, to improve the supply current iS, compensating the harmonic and reactive components of the load current iL. An experimental prototype has been implemented, and the obtained results are presented to support the performance of the proposed design
Remote Control System for Transformers with On-Load Tap Changer
Authors: K. J. Sagastabeitia  , Z. Aginako  , A. J. Mazón  , I. Zamora
Published: July 2017

This paper presents a Remote Control System for Transformers with On-Load Tap Changer. This tool has been designed to be implemented in Remote Telecontrol Units (RTU) located in Transformation Centers (CT) with on-load tap changing capability. Its final application is to provide an integral solution of the telecontrolled on-load tap changer from a Remote Operation Control Position (ROCP), located into the electric company ́s operation office.
Impact of Wind Energy Integration in a Distribution Electric Network
Authors: V. Rogez  , H. ROISSE  , V. Autier  , X. Guillaud
Published: July 2017

This paper deals with the integration of wind farms in amedium voltage isolated grid. Two main aspects aredeveloped and concerns the regulation of the voltage planof the grid without and after with the participation of thewind machines in the regulation of the voltage control.
Real Time Stochastic Simulator of the Electric Power Produced by a Photovoltaic Power System.
Authors: V. Autier  , V. Molcrette  , H. Roisse  , J-L. Kotny
Published: July 2017

The aim of this paper is to build an understandingconcepts of creation of a stochastic generator of the electricalpower delivered by the PV array. Much attention is paid to helpfitters to get simply and rapidly simulations of scenarios of theelectrical power. The developed generator integrated the effectof the clouds layers by 3 SKY-index which are computed by astatistical approach. The irradiance collected by the PV panels,is deduced from an analytical expression of the theoreticalirradiance (without clouds) and the SKY-index. The useddatabases are provided from the 'European daylight and solarradiation database Satel-light', assembled for the period 1996-2000.
Optimization of a wind turbine using permanent magnet synchronous generator (PMSG).
Authors: Jan Vergauwe  , André Martinez  , Alberto Ribas
Published: July 2017

This paper proposes strategies for a Wind Turbine with a Voltage Source Converter (VSC) in the case of a 200-300kW Permanent Magnet Synchronous Generator (PMSG). This control allows the synchronous generator to operate at an optimal speed. To show its effectiveness, a mathematical model of a variable speed wind energy conversion system is developed. The mathematical model is used to calculate the response of the wind energy conversion and to determine the maximum power operating point. This paper also provides the theoretical background of this method. Simulation of the system using Matlab / Simulink / SimPower System was performed to illustrate the advantages of this control strategy.
Modelling of clustered distributed generation for economic requirements.
Authors: M. Neubert  , G. Balzer
Published: July 2017

In this paper,  economical and technicalconsiderations  of  distributed  generation  units  (DGU)will  be presented  in  two  steps.   The  first  one  analyseseconomic side of the distributed generation units.  Thecalculation of total cost as well as the specific generationcost will  be presented.  The last newly defined param-eter allows to compare different distributed generationunits with their own and with traditional thermal powerplants.   In  the  second  step,  the  technical  restrictionslike power stability or load flow will be considered.  Todo  this,  the  model  of  a  low  voltage  (LV)  network  hasbeen created.  The network has been divided into clus-ter, where DGU and loads are included.  The DGU willbe driven in two operating modes:  firstly variable loadaccording to the load curve and secondly with full load.Bringing  these two  models  together  the following  con-clusion will be drawn.  The use of distributed generationunits cannot be considered only from the technical pointof view.  The economic view plays also an important role.
The polymer electrolyte membrane fuel cell as electric energy source, steady state and dynamic behavior
Authors: R. A. Costa  , J. R. Camacho  , S. C. Guimarães Jr  , C. H. Salerno
Published: July 2017

The main objective of this work is to give information on the behavior of three small PEMFC (Polymer Electrolyte Membrane Fuel Cell/Proton Exchange Membrane Fuel Cell) prototypes under static and dynamic load conditions. This is a fuel cell that holds promise in the use for energy in automotive and household applications. A computational model was developed to simulate the static and dynamic performance of this particular type of fuel cell. This model is based on electrochemical equations and takes into consideration the advantages and disadvantages of the device in order to generate power. The model takes into consideration the operating and design parameters of the materials, with the results being compared with practical experiments.
This research gives the possibility to infer, from steady state and dynamic studies, on the design of PEMFC’s of different sizes and also to develop a further research on the need for control such as of hydrogen and oxygen pressure and flow. The study of sizing of the fuel cell is also an invaluable asset due to the low cost of the simulation
Cogeneration in electrical microgrids.
Authors: I. Zamora  , J.I. San Martín Díaz  , A. J. Mazón  , J.J. San Martín Díaz  , V. Aperribay  , J.Mª. Arrieta
Published: July 2017

Simultaneous generation of electrical and useful thermal energy (hot, cold, or both) is an obvious way to optimize the consumed energy efficiency. In the last decade, cogeneration has had, in a world level, a big deployment, thanks to the use of gas and the fact of taking advantage of biomass and other waste products energetically valuable. However, there are possibilities to extend cogeneration applications by means of new technologies of multiple generation of: electrical power, heat, cold, desalination and/or regeneration of water and chemical products in general.
The priority performances about this context are being centered in the development and researching of a distinguished group of electrical micro-generation technologies, which energetic benefits highlight because of a high global index of efficiency. In this group of advanced technologies Fuel Cells, Stirling Motor and Gas Microturbines are included.
Robust converter synchronization to a weak grid through a DFT-based Method.
Authors: António P. Martins  , José C. Ferreira
Published: July 2017

Phasor estimation and symmetrical components estimation is a fundamental task in power electronics converters control. Power conditioning systems like active filters, universal power flow controllers, static compensators, and dynamic voltage restorers, among other ones, need accurate synchronization circuits capable of dealing with very different grid voltage perturbations. Voltage sags and swells, harmonics, spikes and notches, frequency variation, phase steps, DC components and noise, are phenomena that can cause severe malfunction in the control or supervision circuits of such power systems. Additionally, some protection systems are sensitive to some of these parameters and can give wrong actions when they are not expected to. The DFT algorithm is one of best performers in phasor estimation, but is not perfect. The paper accurately describes the DFT errors under frequency variation, decaying DC components and harmonics, and analyzes the instantaneous phasor estimation, with absolute and recursive algorithms. Strong grid voltage perturbations, occurring in weak grids, especially in the grid connection of renewable energies, demand for a DFT-based robust estimation method. The proposed method, as demonstrated by extensive simulations, is capable of handling general grid voltage perturbations, imposing a compromise between dynamic response and accuracy.
Sea energy conversion: Problems and possibilities.
Authors: G. Buigues  , I. Zamora  , A. J. Mazón  , V. Valverde  , F.J. Pérez
Published: July 2017

Nowadays, policies are being developed in many countries in order to decrease their greenhouse gases emissions. While in this area some technologies are widely installed (wind and solar energy), other ones, like the sea energy, could get an important role in the medium and long term. That is why the most relevant technologies associated to the sea energy conversion are presented in this paper: Tidal energy (both the traditional power plants and those based on tidal streams), wave energy and ocean thermal energy conversion.
However, the sea energy conversion is not completely developed yet due to some unsolved technical problems, apart from their high cost. The most important advantages and disadvantages related to each kind of technology are also analyzed in this paper, comparing the main characteristics among them.
Therefore, technological development government policies and the possibility of setting up a related industrial field will be the key actions to make possible the future of the sea energy. Solving the economical and technical problems, it will be possible to make good use of this alternative source of energy, with high energy density.
FACTS devices in distributed generation.
Authors: Melchor Gómez  , Oihane Abarrategu  , Inmaculada Zamora
Published: July 2017

The FACTS devices control the interrelated parameters that rulethe operation of the transmission systems, including the serialimpedance, the derivation impedance, the current, the tension,the phase angle and the muffling of oscillations to differentfrequencies under the nominal frequency. The FACTStechnology has a collection of controllers, that can be usedindividually or co-ordinated with other controls installed in thenetwork, thus permitting to profit better of the network’scharacteristics of control.
The configurations of compensators based on switchedinverters, called static compensators of reactive power, aretoday the most used in the electric current transmissionsystems. The apparition of high-powered electronic converters,makes possible the generation or absorption of reactive powerwithout using banks of condensers or inductors.
The STATCOM is a device connected in derivation that canoperate in networks of transport as well as of distribution. Thefunctions will depend on the type of network in which it will beinstalled, it could fulfill functions of reactive power control andtension regulation, or other functions as power factor regulator,shock absorber of system oscillations or filtering of harmonics,depending on the systems applications and the tension level wewish to install.
Insulator pollution in transmission lines.
Authors: Ramos Hernanz, José A  , Campayo Martín, José J  , Motrico Gogeascoechea, Joseba  , Zamora Belver, Inmaculada
Published: July 2017

none
ATP prediction of voltage sag effect on sensitive loads.
Authors: J. Cardona  , J. Barros
Published: July 2017

The objective of this paper is to analyze the behavior of adjustable speed drives (ASD) connected to the power system under symmetrical voltage sag conditions. An ATP model has been developed to simulate the response of a VSI inverter driving a three-phase induction motor. Speed and voltage control systems are included. The response of mechanical and electrical variables is obtained.
Optimum PI controllers of active power filters for harmonic voltage mitigation in multibus industrial power systems.
Authors: Josef Tlustý  , Viktor Valouch
Published: July 2017

The bus voltage and branch current detection control strategies of the active power filters used in multibus power systems for harmonic voltage mitigation are analysed in terms of the optimum gains of PI controllers
Interharmonics injected into power system by a squirrel-cage induction machine in normal and faulty operation conditions.
Authors: Jan Rusek
Published: July 2017

The  paper  aims  at  examining  interharmonics  injected  into  the  power  supply  system  by  a  healthy  and  faulty  squirrel  cage  induction  machine  operated  at  steady  state.  The  faulty  operation  discussed  encompasses  breaks  in  squirrel  cage  bars, breaks in squirrel cage end ring segments, combined static and  dynamic  eccentricity,  clutch  wobbling  and  vibration  of  bearings.  The  effect  of  these  ailments  is  first  investigated  through  simulations  accomplished  with  a  specially  developed  and   implemented   squirrel   cage   induction   machine   poly-harmonic  model,  as  the  fundamental  harmonic  models  are  not  capable  of  simultaneous  accounting  for  eccentricities,  slotting  and  actual  winding  configuration.  Two  case  studies,  based  on  preregistered  currents  of  big  industrial  machines,  confirm  the  frequencies    of    interharmonics    predicted    by    theory    and    simulations.  The  case  studies  refer  to  broken  bars  and  clutch  wobbling. The case study analyses were accomplished with the system Sp4   developed   for   offline   diagnoses   of   induction   machines.
Speed control of run-of-river variable speed hydro plants.
Authors: J. Fraile-Ardanuy  , J. R. Wilhelmi  , J. Fraile-Mora  , J. I. Pérez  , I. Sarasúa
Published: July 2017

The advantages of adjustable speed hydroelectric generation have been highlighted by several authors. The optimum speed for actual working conditions must be continuously implemented by means of an appropriate control system. This process gives rise to dynamic changes in operation variables. In this paper a speed control of run-of-river adjustable speed hydro plant is presented.
A little plant of reverse osmosis fed by an isolated electrical system.
Authors: A. Pulido  , N. Angulo  , J. Romero  , C. Quintana  , M. Morán
Published: July 2017

none
An improved technique for the estimation of local frequency, fundamental component phasor and instantaneous symmetrical components.
Authors: Mate Lasic  , Marko Sporec  , Irena Klaric
Published: July 2017

Generation of electrical energy in large conventional power plants (thermal, hydro and nuclear) in last ten years worldwide is being supplemented by small generation utilities that are fuelled by renewable sources, waste etc. In Republic of Croatia few years ago first small power plants projects were started. One such project was constructing small thermal power plant as a part of sanitary landfill treatment process in Zagreb, capital of Republic of Croatia. It is first power plant in Republic of Croatia of that kind which is fuelled by landfill gas that is result of decomposition process. After the commissioning of small thermal power plant (STPP) Jakusevec a detailed analysis of voltages and currents at the point of connection to the local distribution network was conducted. Results of that analysis are given in this paper.
Analysis of state of MV distribution system before and after connection of small wind farm Ravna1
Authors: Toni Dropulic  , Mate Lasic  , Jandro Simic
Published: July 2017

In the last two decades, the number of installed wind turbines has grown rapidly all over the world. This was due to the huge improvement in technology and increased interest in using wind energy as an important energy source in the future. Following this worldwide trend, the first small wind farm in Croatia named Ravna1 was installed on the Pag Island. To check its influence on local distribution network, power quality measurements have been made in different points in the network before and after the connection of the small wind farm. In parallel, simulation of the distribution network with its connection to 110 kV network was made, and power flow and voltage analysis were made for cases of network with and without wind farm connected. Analyses were made to check the influence of the connection of the wind park on the relatively weak island network, and were made with different power outputs of wind turbines. Calculated values of power flows and values of voltages in the network match very well with measured ones. Also, measurements show that connection of small wind farm does not affect power quality on the Pag Island distribution network.
The impact of induction generator and PWM inverter with energy storage on weak grids.
Authors: H. Bludszuweit  , J.A. Domínguez  , M. García
Published: July 2017

The impact of wind energy generation connected to a weak grid is studied with SIMULINK® as simulation platform. The wind energy conversion system is modelled by a squirrel cage asynchronous induction machine (ASM). The grid is modelled as an infinite bus. In the proposed system the ASM is connected to the grid through a DC-link with incorporated battery storage. An ultracapacitor (UCap) bank in parallel to the battery reduces the current ripple which is originated by the PWM – IGBT bridges and absorbs rapid power peaks. Different degrees of grid strength for 2 disturbing events (A: 3-phase fault and B: Voltage dip) are studied. The simulation model permits a sizing of the storage system according to the desired stabilizing capabilities of the system.
From the simulation results can be concluded that under weak grid conditions the DC-link need to have a voltage control to ensure the stability of the system. Special attention must be paid to the power quality at the inverter output of the DC-link if renewable generation exceeds 5 % of the short circuit power at the coupling point.
The simulated ASM generator is rated at 75 kW / 400 V. The DC-link operates at 700 V nominal voltage, the battery is rated at 340 kWh (C = 500 Ah), 34 kW at discharge rate C0.1 and 170 kW at discharge rate C0.5 with a UCap of 0.5 F in parallel, rated at 600 A discharge current
Pre-feasibility study of a grid connected wind-PV hybrid system with energy storage and power prediction.
Authors: Hans Bludszuweit  , José Antonio Domínguez Vázquez  , José Luis Bernal
Published: July 2017

A simulation system using Matlab/ Simulink® for battery sizing in grid-connected renewable generation is compared with results from the optimization tool HOMER. The system is intended to reinforce remote weak distribution grids. The power injection of the hybrid generation system to the grid is defined by a power prediction method. The battery smoothes the power output and absorbs the prediction errors. As a reference, a wind – battery system is chosen. The impact of the integration of photovoltaic generation is studied. As an example for the meteorological conditions, wind data from the airport and solar irradiation mean values for Zaragoza are applied. Simulated renewable power ranges from 600 kW to 1.1 MW. The battery sizes obtained from the Matlab simulation differ substantially from HOMER results but show similarities. This is due to the difference in the battery models. Integration of solar generation can reduce battery size relative to total installed power and also reduce total cost of generated energy.
Orthogonal decomposition of currents, power definitions and energy transmission in three-phase systems treated in the time domain.
Authors: Gorazd Štumberger  , Boštjan Polajžer  , Matej Toman  , Drago Dolinar
Published: July 2017

This paper deals with the orthogonal decomposition of currents in a three-phase system. Currents and voltages of the three-phase system are treated as instantaneous values and as continuous functions defined in given interval. In both cases current and voltage vectors are defined. They are decomposed into two orthogonal components. The first one is collinear with the voltage vector while the second one is orthogonal to it. It is shown, that only the current vector component collinear with the voltage vector contributes to the energy transmission and to active power while the current vector component orthogonal to the voltage vector causes reciprocal energy exchange between source and load whose average value equals zero.
Study of an ordinary home electrical consumption in order to make it more energy-efficient.
Authors: António Manuel L. Quadros Flores
Published: July 2017

Taking care of our household energy can lower our annual power costs without making our home less comfortable, but making it more valuable. The purpose of this paper is to show how to turn an ordinary home into a more energy-efficient one. To achieve that goal, we analysed all the electrical appliance consumptions in a real home and starting from there, we made tests and explained the results; in fact, it became more energy-efficient and consequently lowered the electricity bill. The goal of this paper is to make it clear that almost all homes have the potential to become more energy-efficient, not from a theoretical point of view, but from a practical one, starting from real data and ending in the annual savings in the electricity bills. In addition using electricity more efficiently we will be contributing to a more reliable electricity system and we will be doing our part to help protect the environment
Comparative efficiency of switched reluctance and induction motor drives for slowly varying loads.
Authors: P.Andrada  , B. Blanqué  , J.I.Perat  , M. Torrent  , E. Martínez  , J. A. Sánchez
Published: July 2017

A current-controlled switched reluctance motordrive for variable speed applications with efficiency optimization is presented. Firing angles are computed online, the turn-on is calculated by means of the rule of Bose, and the turn-off is calculated using the general theory of the optimal turn-off angle proposed by Gribble. In steady state operation, the initial selection of firing angles is fine-tuned by means of an algorithm that minimizes the input power of the drive. An efficiency and electrical energy consumption comparison with a commercial vector-controlled induction motor drive of the same size is also included. Experimental results show that the proposed switched reluctance motordrive is a good choice for applications that require slow varying loads and energy savings.
Mathematical approach to THD optimisation in multilevel convertors.
Authors: A. Jan Iwaszkiewicz  , B. Jacek Perz
Published: July 2017

The paper is related to the problem of generating the high qual-ity  AC  voltage  waveforms  using  multilevel  converters.  This  technique  can  be  applied  especially  in  the  distributed  power  energy systems with renewable DC voltage sources like photo-voltaic  farms  and  fuel  cells.  A  novel  approach  to  the  synthesis  of  AC  voltage  waveforms,  considering  minimising  of  THD  by  use  of  analytical  methods  like  Fourier  transform  is  presented.  The analysis of the obtained waveforms is presented as well as examples of chosen parameter optimisation. The meaning of the THD factor from the construction point of view is analysed and a  new  bandwidth  factor  THDB,  containing  more  information  about the frequency range of harmonic components is proposed in the paper.
A dynamic model based on a network of magnetically coupled reluctances for asyncrhonous motor fault analysis.
Authors: F. Pedrayes  , C. H. Rojas  , M. F. Cabanas  , M. G. Melero  , G. A. Orcajo  , J. M. Cano
Published: July 2017

The growing application of asynchronous motors in industrial processes that require high security and reliability levels has led to the development of multiple methods for early fault detection. The design and verification of these methods imply the use of complex mathematical models that allow the study of the influence produced by the machine operating conditions over the diagnosis procedure. The present paper describes a model for asynchronous motors based on a network of magnetically coupled reluctances. The aim of this model is its application to the study of the typical failures of this type of machine i. e. rotor asymmetries, airgap eccentricity, operation with an open phase etc. The dynamic properties of the model allow the simulation of the spatial evolution of all the motor variables, without neglecting complex phenomena such as magnetic saturation. Time domain analysis of airgap torque, as well as the calculation of current harmonic components are also possible. This initial study is aimed to check the accuracy and computation economy of the model. To do this, the motor is simulated under rated load operation conditions and the temporal evolution of its main electrical and mechanical variables are obtained.
Energy management of stand-alone power systems with renewable energy sources.
Authors: S. D’Arco  , R. Rizzo  , D. Coll-Mayor  , P. Tricoli
Published: July 2017

The paper deals with storage and generation systems with renewable energy sources. A stand-alone combined system with electrochemical batteries, supercapacitors and fuel cells is considered.
The power flow among the different storage devices is controlled in order to optimise the energetic efficiency and avoid irregular working conditions. A proper control strategy is proposed to keep constant the fuel cell power and limit the charge/discharge batteries current. The control strategy is implemented by means of two hierarchical algorithms on the power converters that interconnect storage devices and generation sources.
Experimental tests done on electrical drives to validate the algorithm are illustrated and the results are discussed.
Influence of the power quality instrument class on the accurate of the PQ measurement.
Authors: Manuel Pérez Donsión  , Santiago Álvarez Lorenzo
Published: July 2017

In order to an accurate interpretacion of the measure results, it has been established an International Standard. The IEC 61000-4 defines the methods for measurement and interpretation of the results. This Standard is applied for power quality parameters in 50/60 a.c. power supply systems. For each relevant type of parameter is described a measurement method. Every method makes possible to obtain reliable, repeatable and comparable results regardless of the compliant instrument being used and regardless of its environmental conditions. During a measurement campaign, we conect the measurement device, for usually a week, on the PCC (Point of Common Coupling) of one factory. It is necessary to take into account the appropriate measurement methods for a successful performance. But if we use different instruments of measure at the same time, we will find differences between theirs results. It is worthwhile asking if the differences between instruments are negligible or not. In order to look for an answer to this question we have made different tests and measurements at the Electromagnetic Compatibility Laboratory and at the PCC of one factory with three different instruments: one of class A (Topas 1000) and two of B class (Unilyzer 812 and Memobox 300 smart). Previously we have compared two Unilazers 812 and also two Mamobox 300 Smart The results and conclusions of this comparison will be presented in this paper.
Formal- and high-structured kinetic process modelling and footprint area analysis of binary imaged cells: Tools to understand and optimize multistage-continuous PHA biosynthesis
Authors: Koller Martin , Vadlja Denis , Braunegg Gerhart , Atlić Aid , Horvat Predrag
Published: July 2017

Competitive polyhydroxyalkanoate (PHAs) production requires progress in microbial strain performance, feedstock selection, downstream processing, and more importantly according to the process design with process kinetics of the microbial growth phase and the phase of product formation. The multistage continuous production in a bioreactor cascade was described for the first time in a continuously operated, flexible five-stage bioreactor cascade that mimics the characteristics involved in the engineering process of tubular plug flow reactors. This process was developed and used for Cupriavidus necator-mediated PHA production at high volumetric and specific PHA productivity (up to 2.31 g/(Lh) and 0.105 g/(gh), respectively). Based on the experimental data, formal kinetic and high structured kinetic models were established, accompanied by footprint area analysis of binary imaged cells. As a result of the study, there has been an enhanced understanding of the long-term continuous PHA production under balanced, transient, and nutrient-deficient conditions that was achieved on both the micro and the macro kinetic level. It can also be concluded that there were novel insights into the complex metabolic occurrences that developed during the multistage- continuous production of PHA as a secondary metabolite. This development was essential in paving the way for further process improvement. At the same time, a new method of specific growth rate and specific production rate based on footprint area analysis was established by using the electron microscope.
Antifungal activity of a biosurfactant-producing lactic acid bacteria strain
Authors: Matei Gabi Mirela , Matei Sorin , Matei Adrian , Draghici Elena
Published: July 2017

Lactic acid bacteria are frequently utilized in food industry and they are also recognized as antimicrobial agents due to their capability to produce metabolites such as: organic acids, biosurfactants, bacteriocins, hydrogen peroxide, cyclic dipeptides, exopolysaccharides. The main goal of this paper was to present the results of the research carried out on the strain LCM2 of lactic acid bacteria isolated from brined cucumbers, for production of biosurfactants and to assess its antifungal properties. The emulsification capacity of biosurfactant was measured using kerosene as the hydrophobic substrate. The value of emulsification index E24 was 89.04% showing a high emulsification activity of the biosurfactant. The structural characterization of biosurfactant by TLC revealed its glycolipidic nature. Assay of the ionic charge established the anionic charge of the biosurfactant revealed by the presence of precipitation lines towards the cationic surfactant dodecyl-dimethyl-ammonium chloride. The biosurfactant presented antibiofilm activity with low adherence capacity, structural damages of the hyphal net, conidiophores and delays or lack of sporulation and decreased biomass accumulation in four mycotoxigenic Penicillium and Aspergillus isolates. Results of in vitro assays recommend the biosurfactant produced by the new lactic acid bacteria strain LCM2 for biotechnological purposes, as alternative antifungal agent in food industry.