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Due to the increasing use of LEDs in lighting systems, the LEDs reliability evaluation is a vitally important issue in the lighting industry, and consequently, the understanding of their failure mechanisms and failure modes are also. Although the construction process of LEDs is similar to other microelectronic devices, there are materials and functional requirements that make their failure modes and mechanisms different. This paper presents a review of research on the failure mechanisms and failure modes of LEDs used in lighting systems. This paper provides a basis for understanding the reliability issues of LEDs, as even the reliability information provided by LED manufacturers is not sufficient for users of this technology. [ABSTRACT FROM AUTHOR]

Three-phase asynchronous motors represent between 60% and 75% of world consumption. Their high incidence in the load curves of a country and, consequently, in the operation of electrical systems makes necessary the development of models that allow their analysis in an effective way and their use in software for the analysis of electrical networks. In any industry there are a large number of electrical machines located in Motor Control Centers all connected to the same busbar. It is possible to group all the motors that are connected to the same busbar forming a single equivalent motor. This paper presents a methodology for obtaining the parameters of an aggregate. From its application to three different case studies, the parameters of a universal aggregate model of a three-phase asynchronous motor for power system analysis are obtained. [ABSTRACT FROM AUTHOR]

The study of the electrical phenomena that originate during the operation of the transformers is of vital importance to predict the consequences that these will bring and to improve the design of the system and of the transformer itself. To carry out these studies it is necessary to use existing simulation tools. The accuracy of the response of the simulation process depends on the degree of detail and the veracity of the data, as well as the type of mathematical model used, so it is necessary to obtain these data and their application in the most suitable model for the simulation of each phenomenon. This paper presents the results of a project that consisted in obtaining, through simulation, the impulse voltage distribution within the transformer windings from a detailed model with the final objective of verifying the effectiveness of the insulating systems used in the transformers prototypes used. [ABSTRACT FROM AUTHOR]

Due to the complexity of LEDs failure modes and mechanisms, its reliability is a key research issue. Existing methods for LEDs reliability prediction only consider one failure mode: lumen degradation or color change; however, working with only one failure mode could limit the scope of the analysis. This paper shows the procedure for obtaining reliability models of white LEDs through of bivariate copulas, from ''times to failure'' taken from the consulted literature. The results obtained show that the best fitting copula model, according to the Akaike Information Criterion (AIC) is the Clayton copula, whose Kendall correlation coefficient indicates that the characteristic parameters ''lumen maintenance" and ''variation of chromaticity coordinates'' are not completely independent. [ABSTRACT FROM AUTHOR]

Optimal distribution networks reconfiguration is very important in reducing losses and operating costs and in improving networks security, stability and reliability indicators. The work objective is reprogramming an algorithm that improves results obtained previously. Paper presents non-dominated classification genetic algorithm II parts adaptation and reprogramming, with a new coding that, unlike previous authors, avoids modified genetic operators and take better advantage of algorithm's potentialities. In addition, graph theory is used to transform non-feasible individuals and avoid new generations of them, dispensing with annoying mesh checking and reducing the search space and computational burden. Proposal's effectiveness was tested with 33 and 70 bars test distribution systems, showing promising results and better than previous proposals. [ABSTRACT FROM AUTHOR]

This paper addresses the current technological advances in the development of facilities for the testing and approval electrical vehicles batteries. Also, the main aspects for the design this kind of laboratory were analyzed with the objective in the near future in Cuba we will build it. Likewise, the most applied techniques and procedures in the world related with diagnosis and certification of electric vehicles batteries were studied. Based on these studies, the safety requirements and the equipment required for made the tests of those batteries were also considerate where the rough acquisition cost and the potential for the implementation in the country was estimated. The results of the investigation demonstrate the benefits of the implementation of this kind battery labs would be achieved, based on the profits it will generate by its use in the country. [ABSTRACT FROM AUTHOR]

This paper, it was analyzed how the angle of inclination and the azimuth influence the generation of a photovoltaic plant. The plants belonging to the 100 MW program, consisting of 30 photovoltaic plants distributed in Cuba, were analyzed. First, the plants with their current design were simulated and the results were compared with the measurements obtained in each plant. The comparison allowed validating the simulations, where the difference remained below 10%, in most cases. The next step was that different angles of inclination and an east-west orientation were analyzed. The results were compared with studies carried out in other parts of the world, where it is proposed that the angle of inclination and the east-west orientation as a new solution to increase the energy produced by a photovoltaic power plant, taking into account the geographical position, climatic conditions and the investment value or cost of the plant. [ABSTRACT FROM AUTHOR]

The existing combined regulation methods do not lead to efficient management of water in isolated hydraulic turbines; these do not prioritize the minimization of the value of the resistive dump load. In this paper, a frequency regulation scheme was proposed that combines a minimum dump resistive load and the flow of the Pelton turbines that operate autonomously. At the begining on this paper was identified the state of the art of autonomous isolated hydro. Also was charactererized in cuban contect and the posibilities of dump load and flow cntrolls methods. Finally was evauated the combination of this two methods due to a generalized cuban study case. The simulation results of the method in Matlab®/Simulink was processed through a case study, from models obtained in previous investigations, contrasted with benchmark reported in the literature. With this scheme it was possible to increase the energy efficiency of autonomous mini-hydroelectric plants. Through simulation the proposed scheme was validated in a way that complies with Cuban standard NC62-04, with a reduction of the resistive dump load at 6% of the generator nominal power value. [ABSTRACT FROM AUTHOR]

Electric Power Systems (EPS) are not conceived without contingency plans for partial and total collapses. National Electric System is constantly threatened by meteorological phenomena, so it is not exempt from the preparation of mentioned plans and it has a procedure in case of collapses of such magnitude. This paper describes the procedure's updating process for total collapses, introducing new strategies to follow for its realization. The restoration's stages after the collapse are briefly detailed. Then, it is proposed to use the strategies of "all open" and restoration in parallel. For their selection, the advantages and disadvantages of these strategies will be taken into account according to the consulted bibliography. In addition, it is proposed how the islands should be formed for the restoration. [ABSTRACT FROM AUTHOR]

The circular economy (CE) model promotes the production of goods and services in a sustainable way, optimizing the consumption of natural resources and mitigating the wastes. In the last years, this model has received a lot of attention and support at the governments' level, internationally; also, in Latin America. Cuba pleads for a sustainable development, with political and incentives for the recycling, the use of the renewable sources and the energy efficiency, as impeller motor of its economic model. Hence, Cuban universities have been requested to include this topic in their study plans, for all the careers. The objective of this paper is to describe how the topic of Circular Economy has been incorporated in the Study Plan of the Electrical Engineering Career at the Technological University of Havana "José A. Echeverría "CUJAE and the results, during the implementation in the 2021 academic year. [ABSTRACT FROM AUTHOR]

In this paper a typical electric vehicle (EV) control system driven by an interior permanent magnet synchronous motor is described. First of all, the mechanical requirements that an EV imposes to its drive are described and explained. The construction, operational characteristics and advantages of an interior permanent magnet synchronous motor that justifies its widespread utilization as an EV drive are explained and justified. Afterward, the control strategy of an EV is exposed and justified. Finally, the Maximum Torque per Ampere (MTPA) control method of an interior permanent magnet synchronous motor is highlighted. Finally, a simulation of a car's electric vehicle driven with a permanent magnet synchronous motor is presented. Four typical scenarios of the operation of the car was selected and through the simulation of motor control system as a whole it was possible to predict the transient performance of the vehicle with the scenarios selected. [ABSTRACT FROM AUTHOR]

This paper approaches the issue of the partial introduction of electric vehicles in the public transport sector, analyzing the possible reduction of environmental pollution and fossil fuel consumption by replacing part of the real fleet as the main aim. Starting from the previous analyzes and the characterization of the vehicles fleet belonging to the company, a substitution is proposed based on the changes that would be made in the associated electrical system, as well as the electric vehicle technology itself through the technical, economic and environmental evaluation, taking into account two prototypes that are currently working. The results of the research show the benefits of replacing internal combustion cars with electric ones, based on the savings obtained in operation and maintenance, as well as the reduction of greenhouse emissions. [ABSTRACT FROM AUTHOR]

This paper presents the methodological development to coordinate the insulation of medium-voltage electrical networks; the study was carried out applying calculation procedures, in which the different factors involved in defining and dimensioning the appropriate insulation level for the equipment making up a primary electrical network are evaluated. In order to carry out insulation coordination, it is necessary to know and determine the operating parameters of the system under analysis and to determine its components, in order to then define the electrical characteristics that the lightning conductor (lightning conductor) must have and, based on the provisions of IEC 60071-1 and IEC 60071-2 standards, to determine the types and levels of overvoltages that could occur in the network, considering the different coordination factors, safety and height correction, in order to cover the defects that may occur in the insulation due to the real operating conditions and thus select an adequate insulation level. [ABSTRACT FROM AUTHOR]

Today, the development of human life depends on the supply of energy obtained mainly from fossil fuels. This resource is limited and its availability finite. Solar energy can meet the needs of the global population. Concentrated solar energy uses a mirrored surfaces that reflects and concentrates the rays in a receiver that absorbs the solar energy transferring it as heat to the fluid that circulates inside it and that can be used in processes that need thermal energy. The efficiency of the system depends on the optical quality of the concentrating mirror. In this paper, the optical efficiency(ηop) of a prototype parabolic disk is determined using a calorimeter, which acts as a receiver, being the value ηop=0,71±0,02. The method is validated by applying a modified Hartmann's optical scanning test, the values wereηop=0,70±0,02 for the of intercept factor method and ηop=0,69±0,02 for the optical simulation. [ABSTRACT FROM AUTHOR]

All the photovoltaic farms in operation in Cuba use monofacial photovoltaic panels. With the technological maturity of the bifacial panel production, since 2018, these have been gaining a growing presence, and it is presumed that in 2021 they will constitute 30% of the world market for solar panels. Bifacial panels, also generating on the reverse side, can increase efficiency between 5 and 30% of the same area. The national and international literature on the subject was reviewed and simulations of a real project in the province of Las Tunas were carried out, assuming an albedo of 0,202 and bifacial modules. This paper was concluded that it is feasible to evaluate the introduction of bifacial panels for future fixed tilt and horizontal single axis tracking projects in Cuba. [ABSTRACT FROM AUTHOR]

The simultaneous tripping of the two end power circuit breaker in the transmission line is one of the complex and costly problem to be solved for the distance protection. The solutions to accelerate the distance protection tripping that not use the communication channels do not reach the necessary requirements. This document presents a bibliographic review of the acceleration methods of distance protections in transmission lines. In this paper is presented first the acceleration methods without communication are presented, investigated and implemented by several scientists and companies that market protection systems for transmission systems and then the conventional methods are referenced, implemented on communication systems to accelerate the operation of protections against failures, and. Also in this document, fault detection and acceleration systems are analyzed, using the traveling wave analysis methodology. [ABSTRACT FROM AUTHOR]

Due to the increased use of LED technology and the complexity of its modes and failure mechanisms, its reliability is a key research issue. To carry out reliability studies based on accelerated test data, the Weibull distribution is generally the most widely used; but in the LEDs, as these are degraded continuously, this distribution may not work with the same efficacy. This paper shows the procedure for obtaining reliability models of white LEDs used in lighting, from non-traditional probability distributions of "times to failure" obtained, according to the criterion L70 of ASSIST, from accelerated testing of the consulted literature. The analyzes carried out with the "times to failure" showed that there is insufficient evidence to reject that the data follow the distributions of Weibull-Exponential Generalized(WGED) and Modified Weibull(MWD), according to the Kolmogorov-Smirnov Test. [ABSTRACT FROM AUTHOR]

The paper starts by casting new light to the existing Phase Lock Loop (PLL) schemes used to synchronize the static converters with the grid under utility disturbances. Two approaches are pursued to detect the fundamental harmonic of the positive-sequence component of the grid voltages in presence of the disturbances. Arithmetical approaches improve the operation of the basic PLL circuit by making robust the PLL algorithm. Structural approaches improve the operation of the basic PLL circuit by adding a block intended to cope with the disturbances. This paper considers the structural approach and shows that it works by either post processing the detected grid quantities or preprocessing the grid voltages. Afterwards, the paper proposes an improved PLL scheme termed as double processing (DP) PLL scheme since it includes preprocessing and post processing functionalities. By properly designing the scheme parameters, it is proved that the proposed scheme exhibits superior robustness against the utility disturbances. [ABSTRACT FROM AUTHOR]

One of the variable speed wind turbines most commonly used today is the doubly feed induction generator(DFIG).A control scheme of DFIG is discussed in this paper. The power converter connected to the grid side (bus) is modeled and controlled using voltage vectororiented dq reference frame, whichguarantees that the active power can be controlled by the daxiscurrent component and consequently the DC bus voltage. The qaxis component is forced to be zero in order to ensurethe unitary power factor. Astator flux oriented control in the rotor circuit converter is used.A novel GDSC - PLL method is used in order to achieve an efficient synchronization with the grid.Onthe order hand, this paper presents an analysis about the DFIG (Double Feed Induction Generator) behavior during voltages sags. [ABSTRACT FROM AUTHOR]

Power transformers (PT) represent an extensive part of the costs structure in an electrical system, so it must to control its state, its ageing and its remnant life, in order to estimate its present and future condition, which is very important to take decisions in operation, maintenance or investments, stimulating an optimal use of financial resources and ensuring reliability and quality. A failure in the PT isolation causes big troubles, produces high repair costs and important financial losses. It is impossible to take maintenance actions on paper-oil isolation, so it is very important to assess its condition, in order to minimize the risk of failures and outages. The work presents a review of the importance of assess the probability of remnant life of PT and an analysis of state-of-the-art concerning methods for implementation of the assessment of that probability. Authors also express the necessity to find out a method to estimate the remnant life of PT, which allow using all the available information about its state, considering different degradation factors. [ABSTRACT FROM AUTHOR]

Actually, with the technological development achieved, the technical systems are increasingly sophisticated and complex. Therefore, the reliability, availability and maintainability of these systems are essential tools to ensure the comfort of everyday life, which is totally dependent on these systems. The objective of this paper is to expose the application of the Probabilistic Safety Analysis, using the CSolv teaching software, in two complex technical systems, as case studies: a STEMAC generator and a transmission subsystem of the electrical system, located in the western region of the country, as an approach to the evaluation of reliability in complex technological systems. As the main result, the minimum sets of failure of the generator set, and of the transmission subsystem were obtained. In the first case, a program for improvement the maintenance management is proposed, demonstrating its importance in the reliability of these systems [ABSTRACT FROM AUTHOR]

Over the last years it has been producing an accelerated introduction of advanced digital technology devices in the residential, commercial and industrial sectors, which has brought a better performance of process and quality of human life, but, at the same time, it has affected the electric power quality. These sectors obtain the electric energy from distribution networks, so it is essential to check them systematically to avoid high monetary losses. In this paper, the characterization of the behavior of power quality discrete parameters is done, specifically the case of sags and swells. To achieve that, a set of statistical techniques and the tolerance curves are employed. These methods are applied to the measurements at the 1200 node placed in Sagua La Grande municipality, in Villa Clara province. The results show the presence of dangerous voltage variations for sensible equipment. [ABSTRACT FROM AUTHOR]

In order to study the phenomena that originate during the operation of the transformers, using the existing tools of simulation with results of an acceptable accuracy, is necessary to obtain real data of the transformers and apply these in a suitable model for each phenomenon. Between these data, the reactances of transformers have great relevance. This paper presents and evaluates the two methods more generalized in the specialized literature of calculation of leakage reactance in transformers of helicoidal concentric windings and is proposed the adjusting of a method described by Kulkarni-Khaparde for its application in rectangular windings. It begins with a brief description of these methods and a discussion of them. The calculation of reactance by the described methods and the proposed variant is developed to a distribution transformer, comparing the theoretical results with the values obtained experimentally on the same transformer, and determining the relative error that yields each procedure with respect to the numerical value of the realized measurements. [ABSTRACT FROM AUTHOR]

This paper presents a procedure to study the dynamics of the frequency of the interconnected system Ecuador-Colombia when a generation unit comes out of the system, and when one doesn't have the necessary information of the electric Colombian system, furthermore the paper presents the results obtained when this procedure is applying it to a real example. [ABSTRACT FROM AUTHOR]

The occurrence of overvoltages is frequent in distribution systems and places people and equipment in danger. In this paper, we present a model, developed with the use of the ATP simulation package, which seeks to describe the variations in voltage caused by different transitory occurrences in these systems. The fundamental causes of transitory overvoltage in distribution systems modeled for this paper are: the drop of a medium-voltage line onto a Iow-voltage line of a different distribution system; voltages induced by lightning strikes on the ground near distribution lines; and overvoltages due to direct lightning strikes on building-top lightning rods, in terms of their grounding connections relative to other grounded elements in the system. [TRANSLATION]

This paper describes a state model for PD (partial discharge) inception voltage in the main insulation of high-power rotating machines. The purposes of the present paper were: to show the behaviour of PD inception voltage under different factors; and to know the relationships between the size of cavities and the instantaneous value of AC applied voltage to the insulation. The objective of this paper is to offer a computational tool able to model the performance of some PD characteristic parameters when the main insulation is under operation conditions. [ABSTRACT FROM AUTHOR]

This paper presents the work of a doctoral thesis on ‘First stage of the process of development of a hydro-motor of high torque: conceptualisation and analytic prototype’. A new focus of design is discussed. It is convenient for the countries that possess a low technological capacity in industry. This new focus was nominated as the process of development of new products guided to the available technological capacity, and their distinctive characteristic is that it uses the technological capacity contained in the products normalised to design products to satisfy social necessities, that in another way they are impossible to design for their elaboration demands. In an application of this procedure, a new type of hydro-motor of radial pistons was obtained with competitive benefits that it can be built by the countries of the third world. The objective of this paper is not to give an itemised explanation of the methodology, But showing its existence and the great utility that this it possesses. [ABSTRACT FROM AUTHOR]

This paper analyzes the influence of the inclination angle of solar modules on the generation of the grid-connected photovoltaic system. The simulations were made with the PVSYST program as well as the real measurements in different operating systems. In this sense, the studies system in the original design were simulated, and were compared with the results obtained by the real measurements at the aforementioned photovoltaic system. The simulations for different inclination angles and their influence on the variation of the electricity generation of the photovoltaic power system was made, as well as, it is carried on the comparison of all obtained results among themselves in search of selecting the best-suited variant for Cuba, in order to fulfill the main objective of the investigation. The main results of this work agree with the most investigations on this subject matter, that is, the optimal inclination angle will be equal to the latitude where place photovoltaic power system. [ABSTRACT FROM AUTHOR]

The Electric System Isolated Cayo Santa María (SEACSM), located in the north of province of Villa Clara, is of vital economic importance to Cuba. During 2013, a group of faults occurred that affected the electrical service provided to the hotel network. This system is weak (due to its condition isolated system) and any failure can lead to the total collapse of the system or loss of a considerable set of loads. That is why it is decided to install a modern substation, which opened in January 2015 to provide a more reliable and stable supply. In this paper we analyze the results of the calculation of the adjustment parameters of the MiCOM P142 and P143 protections of Areva T & D of the new substation, of a very modern technology, which ensure the stability and reliability of the system in four variants of possible operating and expanding the capacity of response before the occurrence of faults. [ABSTRACT FROM AUTHOR]

The Cuban energy sector presents an accelerated growth in fossil fuel generating capacities and the acquisition of technologies based on renewable energies. This sector has been a pioneer in the application of the Cuban norm NC Guide 857 and resolution 224/2014 of the CITMA. The implementation of this regulation allows the strengthening of the integration of the science, technology and innovation system, the development of human resources, metrology, standardization and quality, in the investment processes, from the regulation of the organization and execution process of the metrological assurance programs. The paper shows the main results obtained by the INIMET in the generalization of the program for the training of competencies to Metrology specialists and managers in prioritized companies from different sectors of the economy, with an emphasis on energy sector. [ABSTRACT FROM AUTHOR]

Costa Rica is committed to obtain carbon neutrality; its low level emission energy matrix has been a major contribution in order to accomplish this objective. However, since new power production technologies have been introduced, it is necessary to assess their impact and emissions, even though these are considered as clean technologies. In this paper energy payback time (EPBT) values are estimated, specifically for crystalline silicon photovoltaic systems (monocrystalline and multicrystalline), installed in five different areas throughout the country. Assumptions on the energy consumed for manufacture, transportation and final disposition are stablished in order to quantify EPBT, in contrast with energy produced when using the photovoltaic system. Findings are described from basic Life Cycle Assessment (LCA) perspective. EPBT calculated values range from 2,7 to 3 years, this is important to balance energy during the first stage of a photovoltaic power plant's production in Costa Rica. [ABSTRACT FROM AUTHOR]

The cell and photovoltaic module is typically represented by an equivalent circuit. The correct equivalent circuit modeling is nowadays an essential tool for designers and planners, for studies and optimizes energy in photovoltaic systems. However, the extraction of the equivalent circuit parameters is still a difficult task and typically requires experimental data and calculation procedures, generally not available for the user. This paper presents a new methodology, which enables the exact calculation of the parameters and electrical quantities, simple diode model with five parameters, obtained from the data provided by manufacturers in the data sheets of photovoltaic modules. Finally is showed the validity and accuracy of the proposed methodology, comparing experimental data and curves obtained by the manufacturer of a commercial module, with those obtained by the proposed mathematical model is checked. [ABSTRACT FROM AUTHOR]

In Cuba exists a few studies about the main interaction mechanisms between university and enterprise and their innovative activity performance impact. This interaction has assumed interesting characteristics that can provide lessons for greater contribution to the socio-economic development of the country. The objective of this paper is to analyze the interaction mechanisms between the Cuban enterprises from the electrical sector and a research electrical center of CUJAE. The case study is based on a survey applied to the managers and specialists of the Cuban electricity sector, teachers and researchers from the University. In this work the interaction channels are analized according to their importance to the interaction between both and the results were compared with the results obtained for other Latin America countries. The traditional and bidirectional channels were the most important for both university and enterprise in the present case, and similar results that were obtained in other countries. [ABSTRACT FROM AUTHOR]

Recently it has been producing an accelerated presence of non-linear elements in the residential, commercial and industrial sectors, which has affected the sinusoidal voltage waveform, altering its amplitude and frequency. These sectors obtain the electric energy from distribution networks, so it is essential to check them systematically in order to ensure the power quality according to the established standards. In this paper, a characterization and analysis of the behavior of power quality parameters on distribution electric networks by means of a set of statistical techniques implemented in MATLAB and the employ of representative indices is carried out. For that purpose, the readings of the ION 7650 placed in Sagua municipality are used as an example. The results after the application of these statistical techniques for the characterization of these power quality problems are discussed. [ABSTRACT FROM AUTHOR]

The paper presents a study on the potential of improvements in the technological process of the plants of the province of Cienfuegos, in order to be able to evaluate alternatives to achieve the increase in the delivery of electric energy to the National Electroenergetic System. The five current thermoenergy schemes of the plants under study are described, as well as the Termoazúcar system (STA 4.1) to evaluate a base case in each one of them and to be able to determine the opportunities of improvements from the analysis of operational indicators. The proposed measures are implemented in the improved cases, with the conclusion that changes in the technological process in the plants favor an increase of 12 to 38% of the excess bagasse for each plant, as well as an increase of 22 382.8 kWh / d more than for base cases in the amount of energy sold. [ABSTRACT FROM AUTHOR]

Fault diagnosis in steam turbines is a very important task in power industry maintenance due to its influence on the reliability of power stations. However, research papers that specifically are referred to the determination of the most critical mechanical components and faults in steam turbines cannot be found. This work is focused to determine the most important components and faults in steam turbines in a Cuban power plant. For this purpose, the analysis of history data, since 1999 to 2014, of three 100 MW steam turbines was accomplished. The main achievement of this work was the definition of the most important components and faults, and that was attained by defining a new index (called as "importance" index), which intends to overcome limitations imposed by the specific characteristics of available data. [ABSTRACT FROM AUTHOR]

The objective of this research is to design a methodology to support a process of monitoring, measurement and analysis of energy performance for a leader company in the manufacturing of various types of paper for industrial use. The methodology is based on the pentalogy of Taiichi Ohno offering a chain of five management activities from the need to measure until the selection of energy performance improvements for an organization. The result is a detailed description for the activities for measurement, know, control, management and improvement. Key findings indicate that it is possible to apply the approach Taiichi Ohno to organize a process of monitoring, measurement, control and analysis of energy performance in a manufacturing company supported by consumption indicators, performance and energy savings associated with areas and operational equipment. [ABSTRACT FROM AUTHOR]

In this paper the numerical simulation (using the code Fluent 6.3) of an air solar heater operating on natural convection regime was carried out. The aim was to determine the behavior of velocity and temperature profiles in the heater. The results show that the air temperature increases quasi-linearly with the longitudinal coordinate, independent of the length of the heater. The temperature of the absorber has an abrupt step at entrance and then grows approximately as an exponential. The behavior of the air and plate temperatures is independent of the incident radiation. The air temperature profile maintains its shape along the collector and shows that the temperature drops sharply as it moves away from absorber. The velocity profile starts practically flat at entrance and sets its definitive shape at coordinate close to 40% of the collector length. The maximum velocity of air is located 0.2 channel height taken from the plate. [ABSTRACT FROM AUTHOR]

In the present paper necessary elements to obtain a model in order to achieve criticality and complexity for equipment and technological systems in electric power plants are proposed. This kind of model allows the possibility of establish priority orders to care the assets over real basis. Nowadays the classification of assets made in power plants is far away from the required because it is not in correspondence with specific conditions in each place and also is a fact that there is not an effective tool to make it possible. As a result of the work field done, a personalized model for criticality and complexity in electric power plants was obtained. The application of this tool allows obtaining, through a list or a matrix, the calculated and weighted criticality and complexity values. With these values the organization will be able to set maintenance priorities adequately and improve maintenance management significantly. [ABSTRACT FROM AUTHOR]

Evaluation of frequency behavior errors under disturbance conditions of an electrical power system is essential in order to obtain reliable settings of DAF schemes. Models based in concentrated systems cannot evaluate the influence of local and inter areas oscillations of frequency which are important in the reliable setting of DAF systems. An evaluation of these errors in future Cuban Electric Power System is the main objective of this paper. In this work is taken as a basis for calculating the prospective scenario of the Cuban Power System with the inclusion of two combined cycle and considering the effect of the nonlinear load representing both steelworks arc as randomness of the load due to wind turbines turbulence. It concludes with the values of df / dt measured load nodes and the frequency drop at these nodes are kept lower than the measured values generators nodes. [ABSTRACT FROM AUTHOR]

This paper is proposes a procedure for comparative internal and external risk of management to control the atmospheric emission, which are provoked by steam boiler of service sectors. This are located at different points of the urban zone, with are considered as combustion fixes sources. The proposal takes the most actuality legal and standard documents about the subject as a base. This procedure pays attention to the risk management related to planning, technology, operation and effect of the atmospheric pollution, in order to compare the potential risk and the priority in a making decision processes, in a control action and improvement plan, to achieve the mitigation of effect the atmospheric pollution in Cienfuegos city, Cuba. [ABSTRACT FROM AUTHOR]

The use of supercritical water as a coolant in nuclear reactors is a challenge for its design and operation, it is necessary to consider the strong dependence between the thermodynamic properties of supercritical water and the properties as moderator of neutrons. This paper presents a methodology based on a Monte-Carlo code for neutronic calculation and a Computational Fluid Dynamics code for thermohydraulic calculation, with the aim of making the coupled neutronic-thermohydraulic analysis of a High Performance Light Water Reactorfuel assembly. Using the developed methodology, temperature profiles and power released in the fuel rods, the cladstemperature distribution and the temperature and water density profiles in the cooling and moderator zone were obtained. The results, accurately, describe the behavior of these parameters in the average fuel assembly. [ABSTRACT FROM AUTHOR]

In this paper the possibility of using a cooling system with a desiccant wheel for air treatment of different areas of the case study restaurant is shown. This facility is classified as high consumer of energy, making it necessary to study new alternatives for air conditioning allowing humidity control and energy saving. The literature review conducted on cooling systems with desiccant wheel technology was currently being studied and used as an alternative to saving energy and protecting the environment in the field of air treatment. The desiccant cooling system proposed is fundamentally for a desiccant wheel of silica gel, an energy conservative wheel and a heat exchanger. With the new cooling system electricity demand decreases and significant savings of about 11802 CUC are forecasted only in annual electricity consumption. [ABSTRACT FROM AUTHOR]

Renewable energy, particularly wind, will occupy an important place in the coming decades, marked by the depletion of fossil fuel sources. In Cuba significant growth in the use of these energy sourcesis forecasted. For this reason is importantthe creation of reliable technology to ensure that future mission. The paper proposes as its central objective, the analysis of reliability of Wind Farm Gibara 2 starting from its representation based on the methodology of fault tree and to recommend some possible applications of the results. An essential step in the research is the determination of participating components in the fault tree and processing of the available reliability database at the Wind Farm Gibara 2. The document essentially helpsin the identification of the main contributors to the unavailability of facilities and optimizing maintenance policy. [ABSTRACT FROM AUTHOR]

In this paper the modeling of a flat solar collector for air heating was developed. This collector works with natural convection. The analysis of the collector was made using unsteady mass and energy balances applied to each component of collector. The equations were solved usinga Visual Basic code with the target to simulate the dynamics performance of the collector when the operating conditions and the design parameters are modified. The dimensions of the collector, the material and dimensions of the covert, the material and dimensions of the absorber plate, the optic efficiency and the type and thin of the insulator are the fundamentals design parameters that can be varied. The results of the simulation show that the software can be used for the design of collectors for heating air. Additionally, the software permits to determine the temperature of each component, the instantaneous efficiency of the collector and offers the elements to obtain the time constant that characterize collector dynamics. [ABSTRACT FROM AUTHOR]

The restoration planning is a very important task in the operation of electric power systems. A plan which reduce the duration of the restoration, minimize the impacts of outages in the economy and the society. In this paper it is presented a new method based on automated planning (AP) to restore the transmission network after a blackout. In the early stages of electric power system restoration is important to coordinate simultaneously the generator start-up sequence (GSS) with the branches energization sequence (BES) to decrease the duration of the restoration. The formulations presented in this article are based on automated planning actions, which focus on the identification of transmission paths for the BE Sin simultaneous coordination with the GSS. The tests results de veloped on IEEE39-Bus system demonstrate the efficiency of the algorithm and the quality of the solutions obtained. [ABSTRACT FROM AUTHOR]

In the present paper a mathematical model for the WEKA SR-30102 switched reluctance motor was created using the Simulink development suite. In order to accurately model its behavior, the non-linearity of the motor was taken into account. The mathematical equations that describe the mechanical and electrical properties of the motor were used in order to accurately model the corresponding effects that occur inside the machine. Two different control strategies were created, that is, a closed loop using pulse width modulation and another one using hysteresis control. The mathematical model was validated comparing the experimental and the simulation results. [ABSTRACT FROM AUTHOR]

Shell and tube heat exchangers are ones the most important equipment in the industry. Their thermodynamic design is based on the global heat transference coefficient and the pressure drop. In 2007 was settled a new thermodynamic property denominated "Entransy", which expresses the capacity of a body to transfer heat. The loss of this capacity is denominated "Entransy Dissipation". For evaluating the ecological impact of thermal machines, Angulo-Brown created in 1991 the "ecological function". In this paper the"entransy dissipation" and the ecological function were combined and a new expression for evaluating the ecological impact of shell and tube heat exchangers was created. A multi-objective optimization of this equipment wasalso realized. The ecological function and the cost wereused as objective functions. For carry out the optimization the method of the Genetic Algorithms was used. [ABSTRACT FROM AUTHOR]

This paper proposes a three-dimensional, non-isothermal and steady-state model of Proton Exchange Membrane Fuel Cell using Computational Fluid Dynamic techniques, specifically ANSYS FLUENT 14.5. It's considered multicomponent diffusion and two-phasic flow. The model was compared with experimental published data and with another model. The operation parameters: reactants pressure and temperature, gases flow direction, gas diffusion layer and catalyst layer porosity, reactants humidification and oxygen concentration are analyzed. The model allows the fuel cell design optimization taking in consideration the channels dimensions, the channels length and the membrane thickness. Furthermore, fuel cell performance is analyzed working with SPEEK membrane, an alternative electrolyte to Nafion. In order to carry on membrane material study, it's necessary to modify the expression that describes the electrolyte ionic conductivity. It's found that the device performance has got a great sensibility to pressure, temperature, reactant humidification and oxygen concentration variations. [ABSTRACT FROM AUTHOR]

The present paper aims to make the design of a furnace that allow controlled burning of rice husk for obtain a pozzolanic ash, which is a product demanded for the production of refractory materials and as an reactive addition in high performance concretes. The study will focus on CPA "Eulalio Garcia", which aims to exploit the thermal energy from the combustion gases in different agroindustrial processes. The results show that the volumetric dimension of the combustion chamber will be 0.72 × 0.72 × 1.06 m, while the height and diameter of the stack will be of 6.40 m and 0.42 m, respectively. The excess air ratio will be 1.55 and the volume of air to provide 4.34 m3/kgCA. Furnace efficiency was estimated to be 86.63 % and useful heat in 10585.74 kJ / KgCA. [ABSTRACT FROM AUTHOR]