Departamento de Ingeniería Electrónica y Automática

URI permanente para esta comunidadhttps://hdl.handle.net/10953/38

En esta Comunidad se recogen los documentos generados por el Departamento de Ingeniería Electrónica y Automática y que cumplen los requisitos de Copyright para su difusión en acceso abierto.

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Outdoor evaluation of concentrator photovoltaic systems modules from different manufacturers: first results and steps
(Wiley, 2012-01-31) Fernández-Fernández, Eduardo; García-Loureiro, Antonio Jesús; Pérez-Higueras, Pedro; Gómez-Vidal, Pedro
For the behavior of concentrator photovoltaic systems technology under real conditions to be understood, different modules from different manufacturers were measured in a new research center in Jaén. The influence in the power and the efficiency of irradiation levels, air temperature, and the influence of air mass were under study for 6 months. Pmax shows a linear be- havior with direct normal irradiance, and efficiency was constant to a first approximation for a wide range of irradiance levels. The effect of air temperature was negligible for the temperatures under study. At the same time, efficiency shows a maximum around AM1.5 and decreases aside this point.
Evolución de los computadores: Textos para una exposición
(2012-10-08) Nieto-Nieto, Luis-Miguel
En el texto, de carácter divulgativo, se presentan algunos sistemas que fueron un hito en la evolución histórica de los computadores, desde los primeros artefactos mecánicos de cálculo, hasta los recientes supercomputadores. Ordenados cronológicamente, se comentan piezas de hardware, procesadores y otros dispositivos escogidos por su relevancia, y se incluyen algunas características técnicas y comentarios que los ubican históricamente, y que permiten relacionarlos y comprender su importancia dentro de un contexto tecnológico.
Expert system based on computer vision to estimate the content of impurities in olive oil samples
(ELSEVIER, 2013-06-01) Cano Marchal, Pablo; Martínez Gila, Diego Manuel; Gámez García, Javier; Gómez Ortega, Juan
The determination of the content of impurities is a very frequent analysis performed on virgin olive oil samples, but the official method is quite work-intensive, and it would be convenient to have an alternative approximate method to evaluate the performance of the impurity removal process. In this work we develop a system based on computer vision and pattern recognition to classify the content of impurities of the olive oil samples in three sets, indicative of the goodness of the separation process of olive oil after its extraction from the paste. Starting from the histograms of the channels of the Red–Green–Blue (RGB), CIELAB and Hue-Saturation-Value (HSV) color spaces, we construct an initial input parameter vector and perform a feature extraction previous to the classification. Several linear and non-linear feature extraction techniques were evaluated, and the classifiers used were Support Vector Machines (SVMs) and Artificial Neural Networks (ANNs). The best classification rate achieved was 87.66%, obtained using Kernel Principal Components Analysis (KPCA) and a grade-3-polynomial kernel SVM. The best result using ANNs was 82.38%, yielded by the use of Principal Component Analysis (PCA) with the Perceptron.
Power Gain and Daily Improvement Factor in Stand-Alone Photovoltaic Systems With Maximum Power Point Tracking Charge Regulators. Case of Study: South of Spain
(American Society of Mechanical Engineers, 2013-11) Muñoz-Rodríguez, Francisco José; Jiménez-Castillo, Gabino; Fuentes-Conde, Manuel; Aguilar-Peña, Juan Domingo
The performance reliability of a stand-alone photovoltaic system (SAPV) depends on the long-term performance of the batteries. In this way, a charge controller becomes an essential device which not only prevents the batteries from suffering deep discharges and overvoltages but also monitors the battery state of charge (SOC) in order to maximize charging efficiency and energy availability. At present, pulse width modulated (PWM) charge regulators dominate the market for this type of component in SAPV systems. However, in recent years, to improve energy management, more manufacturers have developed controllers with strategies for maximum power point tracking (MPPT). PWM charge controllers do not always make optimum use of the available power given by the maximum power point and this gives a loss of power. These power losses depend on battery voltage, irradiance and temperature. However, they can be avoided by using a MPPT charge controller which operates the array at its maximum power point under a range of operating conditions, as well as regulating battery charging. The advantage, in terms of energy gain, provided by this type of charge regulator depends on weather conditions. This paper will study the power gain provided by this type of charge controller, depending on the module temperature and the battery voltage. The paper will, additionally, provide a study of the gain in energy yield, also shown as improvement factor, F, for SAPV systems installed in Jaén (South of Spain). This study may illustrate the behavior of these two types of charge controllers in warm weathers, like Mediterranean climates. Furthermore, it will analyze the suitability of MPPT charge controllers and their benefits in this type of climate. It will be shown that MPPT charge regulator global efficiency constitutes a key issue in making a choice between MPPT and PWM charge regulators. The results given here may be not only of interest for SAPV systems with no access to the electricity grid but also for battery back-up PV grid-connected PV (GCPV) systems.
Calculation of the cell temperature of a High Concentrator Photovoltaic (HCPV) module: a study and comparison of different methods
(Elsevier Ltd, 2014-02) Eduardo F. Fernández, F. Almonacid; P. Rodrigo, P. Pérez-Higueras
Ascertaining the operating cell temperature of a high concentrator photovoltaic (HCPV) module is critical because its electrical parameters are influenced by this factor. However, measuring the cell temperature of an HCPV module is a complex task due to the unique features of such a module. This paper calculates the cell temperature in an HCPV module by using different methods to address this important issue. We conducted a comparative study of four methods used to estimate the cell temperature of an HCPV module, including the IEC 60904-5 method, a method based on thermal resistance proposed by the Instituto de Sistemas Fotovoltaicos de Concentración, the Lineal method and an artificial neural network-based method introduced in this paper. The complete procedures, parameters and coefficients required to estimate the cell temperature with each method are provided. The results show that methods based on direct measurements of the HCPV module perform better than methods based on atmospheric parameters. However, all of the studied methods can be used to estimate cell temperatures with an acceptable margin of error.
A method for estimating the cell temperature at maximum power point of a HCPV module under actual operating conditions
(Elsevier Ltd, 2014-05) Eduardo F. Fernández, P. Rodrigo; F. Almonacid, P. Pérez-Higueras
The operating cell temperature of a HCPV module or system is a key factor, because it directly affects efficiency and reliability. Hence, the accurate estimation of cell temperature in a HCPV module is crucial. Under real operating conditions, HCPV modules work at the maximum power point, because they are connected to an inverter. At the maximum power point, the cell temperature is lower than the cell temperature of open circuit, because solar cells are generating power which is not transformed into heat. At present, none of the existing methods are valid to estimate the operating cell temperature of a HCPV module connected to an inverter. In this paper, a procedure for estimating this temperature is introduced. The results show that the proposed method performs effectively in the estimation of the cell temperature in a HCPV module connected to an inverter. In addition, an analysis of the difference between the cell temperature of open circuit and the cell temperature at the maximum power point in a HCPV is conducted and a difference of up to 21 °C has been found.
Analysis of the spectral variations on the performance of high concentrator photovoltaic modules operating under different real climate conditions
(2014-08) Eduardo F. Fernández, F. Almonacid; J. A. Ruiz-Arias, A. Soria-Moya
Multi-junction (MJ) solar cells show an important dependence on the incident spectrum due to the internal series connection of several cells with different band gap energies. The influence of spectral variations on the performance of HCPV modules or systems is different from that in MJ solar cells since they use optical devices to concentrate the light on the solar cell surface. The spectral distribution of irradiance is affected by atmospheric parameters and changes during the course of day, month or year. Because of this, several authors have done different studies to analyse and quantify the spectral effects on the performance of HCPV modules. However, there are still important issues that have not been addressed. In this paper, a deep analysis of the spectral effects on the performance of different HCPV modules with different multi-junction solar cells and Fresnel lenses on an annual time scale and their study and comparison at locations with different climate conditions is conducted. In order to address this issue, ground-based climatologies at the locations studied, spectra simulations with the SMARTS model and the spectral factor of a HCPV module have been used. Results show that the annual spectral losses vary from 6% to 51% depending on the climate conditions of the location and the HCPV module.
Objetos de aprendizaje multimedia en asignaturas de grado en ingeniería: Videocast, Screencast
(XVII Congreso Internacional EDUTEC, 2014-11-12) Aguilar-Peña, Juan Domingo; Rus-Casas, Catalina; Peña-Hita, María de los Ángeles
En esta comunicación presentamos varios videopodcasts elaborados en la Escuela Politécnica Superior de la Universidad de Jaén, dentro de proyectos de innovación docente (videos didácticos, sobre temas específicos concretos, tanto de teoría como de prácticas, grabaciones de clase on line, grabaciones de seminarios con Adobe Connect, screencast sobre algunos programas informáticos…) que servirán como complemento para asignaturas del Grado en Ingeniería Electrónica Industrial, que se imparten en la Universidad de Jaén. La idea es contribuir a la incorporación de una nueva cultura docente que suponga cambios metodológicos, el desarrollo de competencias y la introducción de las TIC, de acuerdo con las directrices del EEES, potenciando el trabajo autónomo del alumno y ayudando a la comprensión de algunos conceptos relacionados con la electrónica. Se comenta la importancia de este recurso didáctico, el videocast, en la docencia universitaria y, a su vez el proceso y materiales necesarios para su elaboración.
On-line system based on hyperspectral information to estimate acidity, moisture and peroxides in olive oil samples
(ELSEVIER, 2015-06-18) Martínez Gila, Diego Manuel; Cano Marchal, Pablo; Gámez García, Javier; Gómez Ortega, Juan
The analysis of the quality of virgin olive oil involves the determination of a series of properties, such as chemical indexes and organoleptic characteristics. In addition, the determination of these properties in real-time could be useful in order to improve the olive oil extraction process since the process parameters could be regulated with the real-time moisture information. In this paper, the feasibility of using a non-invasive hyperspectral device, in order to determine on-line three parameters of the olive oil (free acidity, peroxide index and moisture) is studied. In order to study the correlation between these parameters and the information obtained by the hyperspectral sensor (absorption level), three different methods were applied: genetic algorithms (GA), least absolute shrinkage and selection operator (LASSO), and successive projection algorithm (SPA). From the experimental results, reduced values in cross validation were obtained and the optimal wavelengths were pointed out.
Sorting Olive Batches for the Milling Process Using Image Processing
(MDPI, 2015-07-02) Aguilera-Puerto, Daniel; Martínez-Gila, Diego Manuel; Gámez-García, Javier; Gómez-Ortega, Juan
The quality of virgin olive oil obtained in the milling process is directly bound to the characteristics of the olives. Hence, the correct classification of the different incoming olive batches is crucial to reach the maximum quality of the oil. The aim of this work is to provide an automatic inspection system, based on computer vision, and to classify automatically different batches of olives entering the milling process. The classification is based on the differentiation between ground and tree olives. For this purpose, three different species have been studied (Picudo, Picual and Hojiblanco). The samples have been obtained by picking the olives directly from the tree or from the ground. The feature vector of the samples has been obtained on the basis of the olive image histograms. Moreover, different image preprocessing has been employed, and two classification techniques have been used: these are discriminant analysis and neural networks. The proposed methodology has been validated successfully, obtaining good classification results.
Comparative assessment of the spectral impact on the energy yield of high concentrator and conventional photovoltaic technology
(Elsevier Ltd, 2016-04) Eduardo F. Fernández, Alberto Soria-Moya; Florencia Almonacid, Jorge Aguilera
Photovoltaic materials are spectrally selected and their electrical output is affected by the spectral distribution of the incident irradiance. The performance of high concentrator photovoltaic (HCPV) systems is more influenced by the spectral changes than conventional single-junction photovoltaic (PV) systems due to the use of multi-junction (MJ) solar cells and optical devices. Despite this, the detailed comparison of the spectral impact on the electrical output of HCPV and PV technology under the same atmospheric conditions has not been addressed yet. Because of this, this paper aims to compare the spectral impact on the energy yield of both type of devices at a monthly and annual time scale at several locations with disparate climate conditions. The spectral dependence of both technologies is quantified by using the spectral factor (SF) index in conjunction with the Simple Model of Atmospheric Radiative Transfer of Sunshine (SMARTS) at five locations of the Aerosol Robotic Network (AERONET) database. The present paper shows that the current HCPV systems present annual spectral losses of around 5% with respect to PV systems at representative locations.
Recursos que fomentan un entorno personal de aprendizaje (PLE)
(Magisterio (https://www.magisterio.com.co/), 2016-04) Aguilar-Peña, Juan Domingo; Rus-Casas, Catalina; Jiménez-Torres, Miriam; Muñoz-Rodríguez, Francisco José
El presente artículo presenta una serie de recursos educativos desarrollados en el marco de distintas convocatorias de proyectos de innovación docente. Ellos contribuyen a una nueva estrategia docente centrada en la innovación, el desarrollo de competencias y la introducción efectiva de las TIC en la Educación Superior; además, potencian el trabajo autónomo del estudiante y el cómo debe aprender a lo largo de sus estudios. Se expone cómo se aumentan las posibilidades formativas, en los estudiantes de ingeniería, con la creación de un “Entorno Personal de Aprendizaje” basado en los recursos educativos.
Optimal Production Planning for the Virgin Olive Oil Elaboration Process
(ELSEVIER, 2016-04-25) Cano Marchal, Pablo; Martínez Gila, Diego Manuel; Gámez García, Javier; Gómez Ortega, Juan
The quality and obtained quantity of Virgin Olive Oil is bounded by the characteristics of the olives to be processed, and further determined by the influence of the process variables during the actual elaboration. Since the quality of the olives evolves during the harvesting season, it is relevant to consider when to harvest the olives in order to maximize the profit over the whole season. This work proposes a method to determine an optimal production plan for the whole harvesting season and presents the results obtained in its application to four different scenarios.
Optical Design of a 4-Off-Axis-Unit Cassegrain Ultra-High CPV Module with Central Receiver
(OSA - The Optical Society, 2016-05-01) JUAN P. FERRER-RODRÍGUEZ, EDUARDO F. FERNÁNDEZ; FLORENCIA ALMONACID, PEDRO PÉREZ-HIGUERAS
Ultra-High Concentrator Photovoltaics, UHCPV, with concentrations higher than 1000 suns, has been pointed by different authors to have a great potential for being a cost-effective PV technology. This Letter presents a UHCPV Cassegrain-based optical design in which the sunrays are concentrated and sent from four different and independent paraboloid-hyperboloid pairs optical units onto a single central receiver. The optical design proposed has as main advantage the achievement of ultra-high concentration ratios, using relative small mirrors, with similar performance values of efficiency, acceptance angle and irradiance uniformity than other designs.
CACESOL: Characterization of photovoltaic solar cells and modules. Experimental measurement of the V-I curves
(Journal Science IES, 2016-06-27) Amate-Marchal, M.; Castro-Valderas, J.; Bueno-Rodríguez, R.; Pérez-Jiménez, F. J.; Gómez-Macías, A.; Medina-Rincón, A.; Aguilar-Peña, Juan Domingo; Rus-Casas, Catalina; Muñoz-Rodríguez, Francisco José
La obtención y translación a condiciones estándar de medida (CEM) de las curvas características V-I tomadas a sol real de una célula y módulo fotovoltaico, probablemente sea una de las prácticas imprescindibles en cualquier trabajo de investigación relacionado con la tecnología fotovoltaica. Este trabajo trata de obtener los distintos parámetros de las curvas de funcionamiento de la célula y módulo fotovoltaico, para diferentes condiciones de iluminación (irradiancia), pasar a valores en condiciones estándar de medida y comparar con las proporcionadas en las hojas de características por el fabricantede dispositivos fotovoltaicos (FV). Se demuestra la dependencia de la corriente con la irradiancia recibida sobre la célula solar. Nuestro estudio se realizó en el laboratorio (indoor) y en condiciones a sol real (outdoor) con un mini módulo de silicio monocristalino (CS20M20 de 2,36v, 1.21A, 2.2Wp), y módulo de silicio policristalino (Shell RSM 100S de 100Wp). Los parámetros a medir son: la temperatura de la célula (Tc), temperatura ambiente (Ta), irradiancia (G), la corriente en cortocircuito (ISC), tensión en circuito abierto (VOC). Para la obtención de la curva VI en interior se utilizaron distintos valores de resistencias eléctricas para la medida de la tensión en extremos del módulo y la corriente del circuito. La instrumentación utilizada para la medida de los distintos parámetros fue, termómetro de temperatura de superficie y temperatura ambiente, voltímetro DC, pinza amperimétrica y medidor de irradiancia. Una vez realizadas las distintas medidas, se han hecho los cálculos necesarios para mostrar el comportamiento de los módulos ensayados.
Investigating the impact of weather variables on the energy yield and cost of energy of grid-connected solar concentrator systems
(Elsevier Ltd, 2016-07-01) Eduardo F. Fernández, Diego L. Talavera; Florencia M. Almonacid, Greg P. Smestad
This work connects the electrical performance and economics of High Concentrator Photovoltaic technology beyond the cell and module levels. It analyses the impact of fundamental variables on the calculated energy output and economics of a typical system for real-world solar power plants in five locations with diverse climatic conditions. It was found that there exists a nearly linear relationship between the Final Energy Yield and the average direct normal irradiance, while the cell temperature and spectral AC energy losses ranged from 4.6% to 1.8% and 5.0%–2.4%. The LCOE (Levelised Cost of Electricity) calculations used these insights, together with the specific economic values for each location. The results show that the locations with the higher annual energy yield tend to have the lower LCOE values. In particular, the LCOE ranged from 5.5 c€/kWh to 22.2 c€/kWh for a conservative scenario. However, the sites with the highest final yield do not necessarily present the lowest values of LCOE. The results emphasize the interrelationship between the instantaneous effects of cell temperature and spectrum on the performance of the system, as well as the importance of considering the specific economic parameters to estimate the LCOE at each location.
Quantification of the spectral coupling of atmosphere and photovoltaic system performance: Indexes, methods and impact on energy harvesting
(Elsevier B.V., 2017-04-01) Pedro M. Rodrigo, Eduardo F. Fernández; Florencia M. Almonacid, Pedro J. Pérez-Higueras
Photovoltaic system performance is affected by changes in the input sunlight spectrum. Moreover, the different photovoltaic materials employed show different spectral responses, having different spectral behaviour as a result. Many authors have developed methods and proposed indexes for quantifying the spectral influences in photovoltaic systems under the time-varying weather variables. These methods use different equipment, different procedures and assumptions, present different levels of complexity and accuracy, and have advantages and disadvantages in each specific context and application. In this paper, for the first time, a systematic review of the available methods and photovoltaic spectral indexes is presented. Each alternative is analysed in detail and a comparative study is done. In addition, as several authors have measured and/or calculated the spectral impact on the energy yield of the different photovoltaic technologies at particular locations and climates, the existing results are summarized and discussed in order to elucidate the spectral behaviour of each technology as a function of the relevant atmospheric parameters, i.e. air mass, aerosol optical depth and precipitable water. The presented study covers non-concentrating and high-concentrating photovoltaic technologies and is intended for clarifying the methods available for the spectral analysis and the spectral impact on energy harvesting of the photovoltaic technologies.
Current-voltage dynamics of multi-junction CPV modules under different irradiance levels
(Elsevier Ltd, 2017-10) Eduardo F. Fernández; Juan P. Ferrer-Rodríguez; Florencia Almonacid; Pedro Pérez-Higueras
The current-voltage output of concentrator photovoltaic (CPV) modules shows a complex behaviour under irradiance variations due to the use of multi-junction solar cells and optical elements. The single exponential model (SEM) relates the I-V curve of a PV device and its five characteristic parameters. Hence, it is fundamental to understand the dependence of the SEM model and I-V parameters of CPV modules with irradiance. In this paper, two samples of concentrator modules were characterized under fully controlled conditions by using a CPV solar simulator for light intensities within 700–1000 W/m2. Results show that the photo-generated current increases linearly with irradiance, the diode ideality factor and saturation current present a stable behaviour under irradiance variations while the parasitic resistances, i.e. series and shunt, trend to decrease as the intensity increases. In addition, different approximations are carried out in the SEM model equation to explain the dependence of the performance of the concentrators with light intensity. Finally, the prediction of the I-V curves and key electrical parameters from reference values is discussed. Results show a good fitting of the I-V curves until 750 W/m2 and a high accuracy in the estimations of the electrical parameters with a MAPE lower than 1.2%, a MRE within 1% and a R2 equal of higher than 0.9.
Photovoltaic Device Performance Evaluation Using an Open-Hardware System and Standard Calibrated Laboratory Instruments
(MDPI, 2017-11-15) Jesús Montes Romero, Michel Piliougine; José Vicente Muñoz, Eduardo F. Fernández; Juan De la Casa
This article describes a complete characterization system for photovoltaic devices designed to acquire the current-voltage curve and to process the obtained data. The proposed system can be replicated for educational or research purposes without having wide knowledge about electronic engineering. Using standard calibrated instrumentation, commonly available in any laboratory, the accuracy of measurements is ensured. A capacitive load is used to bias the device due to its versatility and simplicity. The system includes a common part and an interchangeable part that must be designed depending on the electrical characteristics of each PV device. Control software, developed in LabVIEW, controls the equipment, performs automatic campaigns of measurements, and performs additional calculations in real time. These include different procedures to extrapolate the measurements to standard test conditions and methods to obtain the intrinsic parameters of the single diode model. A deep analysis of the uncertainty of measurement is also provided. Finally, the proposed system is validated by comparing the results obtained from some commercial photovoltaic modules to the measurements given by an independently accredited laboratory.
An experimental comparison between commercial hybrid PV-T and simple PV systems intended for BIPV
(Elsevier, 2018) Fuentes-Conde, Manuel; Vivar, Marta; de la Casa, Juan; Aguilera-Tejero, Jorge
The idea of combining both thermal and photovoltaic collectors in hybrid photovoltaic-thermal (PV-T) modules actually shows a great potential for integration on facades and rooftops of buildings, mainly because of the reduced available space and the benefits of the on-site electricity and thermal generation. The objective of this work is to compare the real performance (experimental data obtained under real sun during a year) of a commercial hybrid PV-T system vs. a simple PV system using microinverters, assessing the suitability of one-unit hybrid PV-T systems vs. two separated units – PV systems + Thermal systems – for building integration. The combined efficiency over the span of a full day could reach values up to 80%, but this apparent high value needs to be analysed in detail. From the experimental results, it can be observed that both systems, PV and PV-T, have a good electrical performance. But the PV-T system output does not benefit from the lower module temperatures that it should achieve from the active cooling in its back, presenting the same performance as the simple PV system. Regarding the microinverters configuration performance, it has been very positive working with high efficiencies above 96%, justifying its use in this type of applications. In conclusion, the commercial PV-T system has not performed as expected, showing problems with the integration of the active cooling in the back of the PV modules. At this moment, and despite the potential of PV-T systems for BIPV due to space limitations, commercial PV-T systems are still far from PV and Thermal systems using separately.

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